Add Concat generator for combining multiple generators

docs/generators.md

@@ -1,6 +1,12 @@
 <a id="top"></a>
 # Data Generators
 
+**Contents**<br>
+[Combining `GENERATE` and `SECTION`.](#combining-generate-and-section)<br>
+[Provided generators](#provided-generators)<br>
+[Generator interface](#generator-interface)<br>
+[Other usage examples](#other-usage-examples)<br>
+
 > Introduced in Catch2 2.6.0.
 
 Data generators (also known as _data driven/parametrized test cases_)
@@ -106,7 +112,7 @@ a test case,
 * 2 fundamental generators
   * `SingleValueGenerator<T>` -- contains only single element
   * `FixedValuesGenerator<T>` -- contains multiple elements
-* 5 generic generators that modify other generators (defined in `catch2/generators/catch_generators_adapters.hpp`)
+* 6 generic generators that modify other generators (defined in `catch2/generators/catch_generators_adapters.hpp`)
   * `FilterGenerator<T, Predicate>` -- filters out elements from a generator
   for which the predicate returns "false"
   * `TakeGenerator<T>` -- takes first `n` elements from a generator
@@ -114,6 +120,7 @@ a test case,
   * `MapGenerator<T, U, Func>` -- returns the result of applying `Func`
   on elements from a different generator
   * `ChunkGenerator<T>` -- returns chunks (inside `std::vector`) of n elements from a generator
+  * `ConcatGenerator<T>` -- returns elements from multiple generators as if they were one
 * 2 random generators (defined in `catch2/generators/catch_generators_random.hpp`)
   * `RandomIntegerGenerator<Integral>` -- generates random Integrals from range
   * `RandomFloatGenerator<Float>` -- generates random Floats from range
@@ -125,6 +132,8 @@ a test case,
 
 > `IteratorGenerator<T>` was introduced in Catch2 2.10.0.
 
+> `ConcatGenerator<T>` was introduced in Catch2 X.Y.Z
+
 The generators also have associated helper functions that infer their
 type, making their usage much nicer. These are
 
@@ -142,6 +151,7 @@ type, making their usage much nicer. These are
 * `range(Arithmetic start, Arithmetic end, Arithmetic step)` for `RangeGenerator<Arithmetic>` with a custom step size
 * `from_range(InputIterator from, InputIterator to)` for `IteratorGenerator<T>`
 * `from_range(Container const&)` for `IteratorGenerator<T>`
+* `cat(GeneratorWrapper<T>&&...)` for `ConcatGenerator<T>`
 
 > `chunk()`, `random()` and both `range()` functions were introduced in Catch2 2.7.0.
 
@@ -149,6 +159,8 @@ type, making their usage much nicer. These are
 
 > `range()` for floating point numbers has been introduced in Catch2 2.11.0
 
+> `cat` has been introduced in Catch2 X.Y.Z
+
 And can be used as shown in the example below to create a generator
 that returns 100 odd random number:
 
@@ -278,6 +290,32 @@ to be an error or not.
  * If empty generator **is not** an error, use the [`SKIP` macro](skipping-passing-failing.md#skipping-test-cases-at-runtime) in constructor.
 
 
+## Other usage examples
+
+### Adding a reproducer to random tests
+
+If you use generators to generate random inputs for testing, you might
+want to combine them with specific inputs, e.g. reproducers for previously
+found issues.
+
+Because `GENERATE` accepts multiple values/generators, the basic case is simple:
+```cpp
+const int input = GENERATE(1, 2, take(10, random(10, 10'000'000)));
+```
+This will set `input` first to "1", then to "2", and then to 10 random
+integers.
+
+But if you process the random inputs further (e.g. via `map`), you can't
+rely on `GENERATE`'s support for multiple generators. In that case, you
+have to use the `cat` generator combinator.
+```cpp
+const auto input = GENERATE(
+    map( foo,
+         cat( value( 4 ), take( 10, random( 10, 10'000'000 ) ) ) ) );
+```
+This will set `input` first to `foo(4)`, before transforming the 10 random
+integers through `foo`.
+
 
 ---
 

src/catch2/generators/catch_generators_adapters.hpp

@@ -234,6 +234,49 @@ namespace Generators {
         );
     }
 
+    template <typename T>
+    class ConcatGenerator final : public IGenerator<T> {
+        std::vector<GeneratorWrapper<T>> m_generators;
+        size_t m_current_generator = 0;
+
+        void InsertGenerators( GeneratorWrapper<T>&& gen ) {
+            m_generators.push_back( CATCH_MOVE( gen ) );
+        }
+
+        template <typename... Generators>
+        void InsertGenerators( GeneratorWrapper<T>&& gen, Generators&&... gens ) {
+            m_generators.push_back( CATCH_MOVE( gen ) );
+            InsertGenerators( CATCH_MOVE( gens )... );
+        }
+
+    public:
+        template <typename... Generators>
+        ConcatGenerator( Generators&&... generators ) {
+            InsertGenerators( CATCH_MOVE( generators )... );
+        }
+
+        T const& get() const override {
+            return m_generators[m_current_generator].get();
+        }
+        bool next() override {
+            const bool success = m_generators[m_current_generator].next();
+            if ( success ) { return true; }
+
+            // If current generator is used up, we have to move to the next one
+            ++m_current_generator;
+            return m_current_generator < m_generators.size();
+        }
+    };
+
+    template <typename T, typename... Generators>
+    GeneratorWrapper<T> cat( GeneratorWrapper<T>&& generator,
+                             Generators&&... generators ) {
+        return GeneratorWrapper<T>(
+            Catch::Detail::make_unique<ConcatGenerator<T>>(
+            CATCH_MOVE( generator ), CATCH_MOVE( generators )... ) );
+    }
+
+
 } // namespace Generators
 } // namespace Catch
 

tests/SelfTest/Baselines/automake.sw.approved.txt

@@ -131,6 +131,7 @@ Nor would this
 :test-result: PASS Comparisons with int literals don't warn when mixing signed/ unsigned
 :test-result: PASS Composed generic matchers shortcircuit
 :test-result: PASS Composed matchers shortcircuit
+:test-result: PASS ConcatGenerator
 :test-result: FAIL Contains string matcher
 :test-result: PASS Copy and then generate a range
 :test-result: PASS Cout stream properly declares it writes to stdout
@@ -334,6 +335,7 @@ Message from section two
 :test-result: PASS array<int, N> -> toString
 :test-result: PASS benchmark function call
 :test-result: PASS boolean member
+:test-result: PASS cat generator
 :test-result: PASS checkedElse
 :test-result: FAIL checkedElse, failing
 :test-result: PASS checkedIf

tests/SelfTest/Baselines/automake.sw.multi.approved.txt

@@ -129,6 +129,7 @@
 :test-result: PASS Comparisons with int literals don't warn when mixing signed/ unsigned
 :test-result: PASS Composed generic matchers shortcircuit
 :test-result: PASS Composed matchers shortcircuit
+:test-result: PASS ConcatGenerator
 :test-result: FAIL Contains string matcher
 :test-result: PASS Copy and then generate a range
 :test-result: PASS Cout stream properly declares it writes to stdout
@@ -327,6 +328,7 @@
 :test-result: PASS array<int, N> -> toString
 :test-result: PASS benchmark function call
 :test-result: PASS boolean member
+:test-result: PASS cat generator
 :test-result: PASS checkedElse
 :test-result: FAIL checkedElse, failing
 :test-result: PASS checkedIf

tests/SelfTest/Baselines/compact.sw.approved.txt

@@ -540,6 +540,18 @@ Matchers.tests.cpp:<line number>: passed: !second.matchCalled for: true
 Matchers.tests.cpp:<line number>: passed: matcher.match( 1 ) for: true
 Matchers.tests.cpp:<line number>: passed: first.matchCalled for: true
 Matchers.tests.cpp:<line number>: passed: !second.matchCalled for: true
+GeneratorsImpl.tests.cpp:<line number>: passed: c.get() == 1 for: 1 == 1
+GeneratorsImpl.tests.cpp:<line number>: passed: !(c.next()) for: !false
+GeneratorsImpl.tests.cpp:<line number>: passed: c.get() == i + 1 for: 1 == 1
+GeneratorsImpl.tests.cpp:<line number>: passed: c.next() for: true
+GeneratorsImpl.tests.cpp:<line number>: passed: c.get() == i + 1 for: 2 == 2
+GeneratorsImpl.tests.cpp:<line number>: passed: c.next() for: true
+GeneratorsImpl.tests.cpp:<line number>: passed: c.get() == i + 1 for: 3 == 3
+GeneratorsImpl.tests.cpp:<line number>: passed: c.next() for: true
+GeneratorsImpl.tests.cpp:<line number>: passed: c.get() == i + 1 for: 4 == 4
+GeneratorsImpl.tests.cpp:<line number>: passed: c.next() for: true
+GeneratorsImpl.tests.cpp:<line number>: passed: c.get() == 5 for: 5 == 5
+GeneratorsImpl.tests.cpp:<line number>: passed: !(c.next()) for: !false
 Matchers.tests.cpp:<line number>: failed: testStringForMatching(), ContainsSubstring( "not there", Catch::CaseSensitive::No ) for: "this string contains 'abc' as a substring" contains: "not there" (case insensitive)
 Matchers.tests.cpp:<line number>: failed: testStringForMatching(), ContainsSubstring( "STRING" ) for: "this string contains 'abc' as a substring" contains: "STRING"
 Generators.tests.cpp:<line number>: passed: elem % 2 == 1 for: 1 == 1
@@ -2483,6 +2495,14 @@ InternalBenchmark.tests.cpp:<line number>: passed: model.started == 0 for: 0 ==
 InternalBenchmark.tests.cpp:<line number>: passed: model.finished == 0 for: 0 == 0
 InternalBenchmark.tests.cpp:<line number>: passed: called == 1 for: 1 == 1
 Tricky.tests.cpp:<line number>: passed: obj.prop != 0 for: 0x<hex digits> != 0
+Generators.tests.cpp:<line number>: passed: input < 3 for: 0 < 3
+Generators.tests.cpp:<line number>: passed: input < 3 for: 1 < 3
+Generators.tests.cpp:<line number>: passed: input < 3 for: 2 < 3
+Generators.tests.cpp:<line number>: passed: input % 2 == 0 for: 0 == 0
+Generators.tests.cpp:<line number>: passed: input % 2 == 0 for: 0 == 0
+Generators.tests.cpp:<line number>: passed: input % 2 == 0 for: 0 == 0
+Generators.tests.cpp:<line number>: passed: input % 2 == 0 for: 0 == 0
+Generators.tests.cpp:<line number>: passed: input % 2 == 0 for: 0 == 0
 Misc.tests.cpp:<line number>: passed: flag for: true
 Misc.tests.cpp:<line number>: passed: testCheckedElse( true ) for: true
 Misc.tests.cpp:<line number>: failed - but was ok: flag for: false
@@ -2895,7 +2915,7 @@ InternalBenchmark.tests.cpp:<line number>: passed: med == 18. for: 18.0 == 18.0
 InternalBenchmark.tests.cpp:<line number>: passed: q3 == 23. for: 23.0 == 23.0
 Misc.tests.cpp:<line number>: passed:
 Misc.tests.cpp:<line number>: passed:
-test cases:  437 |  317 passed |  96 failed | 6 skipped | 18 failed as expected
-assertions: 2311 | 2110 passed | 158 failed | 43 failed as expected
+test cases:  439 |  319 passed |  96 failed | 6 skipped | 18 failed as expected
+assertions: 2331 | 2130 passed | 158 failed | 43 failed as expected
 
 

tests/SelfTest/Baselines/compact.sw.multi.approved.txt

@@ -538,6 +538,18 @@ Matchers.tests.cpp:<line number>: passed: !second.matchCalled for: true
 Matchers.tests.cpp:<line number>: passed: matcher.match( 1 ) for: true
 Matchers.tests.cpp:<line number>: passed: first.matchCalled for: true
 Matchers.tests.cpp:<line number>: passed: !second.matchCalled for: true
+GeneratorsImpl.tests.cpp:<line number>: passed: c.get() == 1 for: 1 == 1
+GeneratorsImpl.tests.cpp:<line number>: passed: !(c.next()) for: !false
+GeneratorsImpl.tests.cpp:<line number>: passed: c.get() == i + 1 for: 1 == 1
+GeneratorsImpl.tests.cpp:<line number>: passed: c.next() for: true
+GeneratorsImpl.tests.cpp:<line number>: passed: c.get() == i + 1 for: 2 == 2
+GeneratorsImpl.tests.cpp:<line number>: passed: c.next() for: true
+GeneratorsImpl.tests.cpp:<line number>: passed: c.get() == i + 1 for: 3 == 3
+GeneratorsImpl.tests.cpp:<line number>: passed: c.next() for: true
+GeneratorsImpl.tests.cpp:<line number>: passed: c.get() == i + 1 for: 4 == 4
+GeneratorsImpl.tests.cpp:<line number>: passed: c.next() for: true
+GeneratorsImpl.tests.cpp:<line number>: passed: c.get() == 5 for: 5 == 5
+GeneratorsImpl.tests.cpp:<line number>: passed: !(c.next()) for: !false
 Matchers.tests.cpp:<line number>: failed: testStringForMatching(), ContainsSubstring( "not there", Catch::CaseSensitive::No ) for: "this string contains 'abc' as a substring" contains: "not there" (case insensitive)
 Matchers.tests.cpp:<line number>: failed: testStringForMatching(), ContainsSubstring( "STRING" ) for: "this string contains 'abc' as a substring" contains: "STRING"
 Generators.tests.cpp:<line number>: passed: elem % 2 == 1 for: 1 == 1
@@ -2476,6 +2488,14 @@ InternalBenchmark.tests.cpp:<line number>: passed: model.started == 0 for: 0 ==
 InternalBenchmark.tests.cpp:<line number>: passed: model.finished == 0 for: 0 == 0
 InternalBenchmark.tests.cpp:<line number>: passed: called == 1 for: 1 == 1
 Tricky.tests.cpp:<line number>: passed: obj.prop != 0 for: 0x<hex digits> != 0
+Generators.tests.cpp:<line number>: passed: input < 3 for: 0 < 3
+Generators.tests.cpp:<line number>: passed: input < 3 for: 1 < 3
+Generators.tests.cpp:<line number>: passed: input < 3 for: 2 < 3
+Generators.tests.cpp:<line number>: passed: input % 2 == 0 for: 0 == 0
+Generators.tests.cpp:<line number>: passed: input % 2 == 0 for: 0 == 0
+Generators.tests.cpp:<line number>: passed: input % 2 == 0 for: 0 == 0
+Generators.tests.cpp:<line number>: passed: input % 2 == 0 for: 0 == 0
+Generators.tests.cpp:<line number>: passed: input % 2 == 0 for: 0 == 0
 Misc.tests.cpp:<line number>: passed: flag for: true
 Misc.tests.cpp:<line number>: passed: testCheckedElse( true ) for: true
 Misc.tests.cpp:<line number>: failed - but was ok: flag for: false
@@ -2884,7 +2904,7 @@ InternalBenchmark.tests.cpp:<line number>: passed: med == 18. for: 18.0 == 18.0
 InternalBenchmark.tests.cpp:<line number>: passed: q3 == 23. for: 23.0 == 23.0
 Misc.tests.cpp:<line number>: passed:
 Misc.tests.cpp:<line number>: passed:
-test cases:  437 |  317 passed |  96 failed | 6 skipped | 18 failed as expected
-assertions: 2311 | 2110 passed | 158 failed | 43 failed as expected
+test cases:  439 |  319 passed |  96 failed | 6 skipped | 18 failed as expected
+assertions: 2331 | 2130 passed | 158 failed | 43 failed as expected
 
 

tests/SelfTest/Baselines/console.std.approved.txt

@@ -1743,6 +1743,6 @@ due to unexpected exception with message:
   Why would you throw a std::string?
 
 ===============================================================================
-test cases:  437 |  335 passed |  76 failed | 7 skipped | 19 failed as expected
-assertions: 2289 | 2110 passed | 136 failed | 43 failed as expected
+test cases:  439 |  337 passed |  76 failed | 7 skipped | 19 failed as expected
+assertions: 2309 | 2130 passed | 136 failed | 43 failed as expected
 

tests/SelfTest/Baselines/console.sw.approved.txt

@@ -3911,6 +3911,80 @@ Matchers.tests.cpp:<line number>: PASSED:
 with expansion:
   true
 
+-------------------------------------------------------------------------------
+ConcatGenerator
+  Cat support single-generator construction
+-------------------------------------------------------------------------------
+GeneratorsImpl.tests.cpp:<line number>
+...............................................................................
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( c.get() == 1 )
+with expansion:
+  1 == 1
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE_FALSE( c.next() )
+with expansion:
+  !false
+
+-------------------------------------------------------------------------------
+ConcatGenerator
+  Iterating over multiple generators
+-------------------------------------------------------------------------------
+GeneratorsImpl.tests.cpp:<line number>
+...............................................................................
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( c.get() == i + 1 )
+with expansion:
+  1 == 1
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( c.next() )
+with expansion:
+  true
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( c.get() == i + 1 )
+with expansion:
+  2 == 2
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( c.next() )
+with expansion:
+  true
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( c.get() == i + 1 )
+with expansion:
+  3 == 3
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( c.next() )
+with expansion:
+  true
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( c.get() == i + 1 )
+with expansion:
+  4 == 4
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( c.next() )
+with expansion:
+  true
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( c.get() == 5 )
+with expansion:
+  5 == 5
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE_FALSE( c.next() )
+with expansion:
+  !false
+
 -------------------------------------------------------------------------------
 Contains string matcher
 -------------------------------------------------------------------------------
@@ -16440,6 +16514,102 @@ Tricky.tests.cpp:<line number>: PASSED:
 with expansion:
   0x<hex digits> != 0
 
+-------------------------------------------------------------------------------
+cat generator
+  Simple usage
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( input < 3 )
+with expansion:
+  0 < 3
+
+-------------------------------------------------------------------------------
+cat generator
+  Simple usage
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( input < 3 )
+with expansion:
+  1 < 3
+
+-------------------------------------------------------------------------------
+cat generator
+  Simple usage
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( input < 3 )
+with expansion:
+  2 < 3
+
+-------------------------------------------------------------------------------
+cat generator
+  Used in map
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( input % 2 == 0 )
+with expansion:
+  0 == 0
+
+-------------------------------------------------------------------------------
+cat generator
+  Used in map
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( input % 2 == 0 )
+with expansion:
+  0 == 0
+
+-------------------------------------------------------------------------------
+cat generator
+  Used in map
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( input % 2 == 0 )
+with expansion:
+  0 == 0
+
+-------------------------------------------------------------------------------
+cat generator
+  Used in map
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( input % 2 == 0 )
+with expansion:
+  0 == 0
+
+-------------------------------------------------------------------------------
+cat generator
+  Used in map
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( input % 2 == 0 )
+with expansion:
+  0 == 0
+
 -------------------------------------------------------------------------------
 checkedElse
 -------------------------------------------------------------------------------
@@ -19372,6 +19542,6 @@ Misc.tests.cpp:<line number>
 Misc.tests.cpp:<line number>: PASSED:
 
 ===============================================================================
-test cases:  437 |  317 passed |  96 failed | 6 skipped | 18 failed as expected
-assertions: 2311 | 2110 passed | 158 failed | 43 failed as expected
+test cases:  439 |  319 passed |  96 failed | 6 skipped | 18 failed as expected
+assertions: 2331 | 2130 passed | 158 failed | 43 failed as expected
 

tests/SelfTest/Baselines/console.sw.multi.approved.txt

@@ -3909,6 +3909,80 @@ Matchers.tests.cpp:<line number>: PASSED:
 with expansion:
   true
 
+-------------------------------------------------------------------------------
+ConcatGenerator
+  Cat support single-generator construction
+-------------------------------------------------------------------------------
+GeneratorsImpl.tests.cpp:<line number>
+...............................................................................
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( c.get() == 1 )
+with expansion:
+  1 == 1
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE_FALSE( c.next() )
+with expansion:
+  !false
+
+-------------------------------------------------------------------------------
+ConcatGenerator
+  Iterating over multiple generators
+-------------------------------------------------------------------------------
+GeneratorsImpl.tests.cpp:<line number>
+...............................................................................
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( c.get() == i + 1 )
+with expansion:
+  1 == 1
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( c.next() )
+with expansion:
+  true
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( c.get() == i + 1 )
+with expansion:
+  2 == 2
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( c.next() )
+with expansion:
+  true
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( c.get() == i + 1 )
+with expansion:
+  3 == 3
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( c.next() )
+with expansion:
+  true
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( c.get() == i + 1 )
+with expansion:
+  4 == 4
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( c.next() )
+with expansion:
+  true
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE( c.get() == 5 )
+with expansion:
+  5 == 5
+
+GeneratorsImpl.tests.cpp:<line number>: PASSED:
+  REQUIRE_FALSE( c.next() )
+with expansion:
+  !false
+
 -------------------------------------------------------------------------------
 Contains string matcher
 -------------------------------------------------------------------------------
@@ -16433,6 +16507,102 @@ Tricky.tests.cpp:<line number>: PASSED:
 with expansion:
   0x<hex digits> != 0
 
+-------------------------------------------------------------------------------
+cat generator
+  Simple usage
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( input < 3 )
+with expansion:
+  0 < 3
+
+-------------------------------------------------------------------------------
+cat generator
+  Simple usage
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( input < 3 )
+with expansion:
+  1 < 3
+
+-------------------------------------------------------------------------------
+cat generator
+  Simple usage
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( input < 3 )
+with expansion:
+  2 < 3
+
+-------------------------------------------------------------------------------
+cat generator
+  Used in map
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( input % 2 == 0 )
+with expansion:
+  0 == 0
+
+-------------------------------------------------------------------------------
+cat generator
+  Used in map
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( input % 2 == 0 )
+with expansion:
+  0 == 0
+
+-------------------------------------------------------------------------------
+cat generator
+  Used in map
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( input % 2 == 0 )
+with expansion:
+  0 == 0
+
+-------------------------------------------------------------------------------
+cat generator
+  Used in map
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( input % 2 == 0 )
+with expansion:
+  0 == 0
+
+-------------------------------------------------------------------------------
+cat generator
+  Used in map
+-------------------------------------------------------------------------------
+Generators.tests.cpp:<line number>
+...............................................................................
+
+Generators.tests.cpp:<line number>: PASSED:
+  REQUIRE( input % 2 == 0 )
+with expansion:
+  0 == 0
+
 -------------------------------------------------------------------------------
 checkedElse
 -------------------------------------------------------------------------------
@@ -19361,6 +19531,6 @@ Misc.tests.cpp:<line number>
 Misc.tests.cpp:<line number>: PASSED:
 
 ===============================================================================
-test cases:  437 |  317 passed |  96 failed | 6 skipped | 18 failed as expected
-assertions: 2311 | 2110 passed | 158 failed | 43 failed as expected
+test cases:  439 |  319 passed |  96 failed | 6 skipped | 18 failed as expected
+assertions: 2331 | 2130 passed | 158 failed | 43 failed as expected
 

tests/SelfTest/Baselines/junit.sw.approved.txt

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <testsuitesloose text artifact
 >
-  <testsuite name="<exe-name>" errors="17" failures="141" skipped="12" tests="2323" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
+  <testsuite name="<exe-name>" errors="17" failures="141" skipped="12" tests="2343" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
     <properties>
       <property name="random-seed" value="1"/>
       <property name="filters" value="&quot;*&quot; ~[!nonportable] ~[!benchmark] ~[approvals]"/>
@@ -501,6 +501,9 @@ at Message.tests.cpp:<line number>
     <testcase classname="<exe-name>.global" name="Composed matchers shortcircuit" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Composed matchers shortcircuit/MatchAllOf" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Composed matchers shortcircuit/MatchAnyOf" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="ConcatGenerator" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="ConcatGenerator/Cat support single-generator construction" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="ConcatGenerator/Iterating over multiple generators" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Contains string matcher" time="{duration}" status="run">
       <failure message="testStringForMatching(), ContainsSubstring( &quot;not there&quot;, Catch::CaseSensitive::No )" type="CHECK_THAT">
 FAILED:
@@ -1993,6 +1996,9 @@ at Skip.tests.cpp:<line number>
     <testcase classname="<exe-name>.global" name="benchmark function call/without chronometer" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="benchmark function call/with chronometer" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="boolean member" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="cat generator" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="cat generator/Simple usage" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="cat generator/Used in map" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="checkedElse" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="checkedElse, failing" time="{duration}" status="run">
       <failure message="testCheckedElse( false )" type="REQUIRE">

tests/SelfTest/Baselines/junit.sw.multi.approved.txt

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <testsuites>
-  <testsuite name="<exe-name>" errors="17" failures="141" skipped="12" tests="2323" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
+  <testsuite name="<exe-name>" errors="17" failures="141" skipped="12" tests="2343" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
     <properties>
       <property name="random-seed" value="1"/>
       <property name="filters" value="&quot;*&quot; ~[!nonportable] ~[!benchmark] ~[approvals]"/>
@@ -500,6 +500,9 @@ at Message.tests.cpp:<line number>
     <testcase classname="<exe-name>.global" name="Composed matchers shortcircuit" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Composed matchers shortcircuit/MatchAllOf" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Composed matchers shortcircuit/MatchAnyOf" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="ConcatGenerator" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="ConcatGenerator/Cat support single-generator construction" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="ConcatGenerator/Iterating over multiple generators" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="Contains string matcher" time="{duration}" status="run">
       <failure message="testStringForMatching(), ContainsSubstring( &quot;not there&quot;, Catch::CaseSensitive::No )" type="CHECK_THAT">
 FAILED:
@@ -1992,6 +1995,9 @@ at Skip.tests.cpp:<line number>
     <testcase classname="<exe-name>.global" name="benchmark function call/without chronometer" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="benchmark function call/with chronometer" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="boolean member" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="cat generator" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="cat generator/Simple usage" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="cat generator/Used in map" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="checkedElse" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="checkedElse, failing" time="{duration}" status="run">
       <failure message="testCheckedElse( false )" type="REQUIRE">

tests/SelfTest/Baselines/sonarqube.sw.approved.txt

@@ -145,6 +145,9 @@ at AssertionHandler.tests.cpp:<line number>
     <testCase name="convertToBits" duration="{duration}"/>
   </file>
   <file path="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp">
+    <testCase name="ConcatGenerator" duration="{duration}"/>
+    <testCase name="ConcatGenerator/Cat support single-generator construction" duration="{duration}"/>
+    <testCase name="ConcatGenerator/Iterating over multiple generators" duration="{duration}"/>
     <testCase name="Filter generator throws exception for empty generator" duration="{duration}"/>
     <testCase name="Generators internals" duration="{duration}"/>
     <testCase name="Generators internals/Single value" duration="{duration}"/>
@@ -1242,6 +1245,9 @@ at Generators.tests.cpp:<line number>
     <testCase name="Generators -- simple/one" duration="{duration}"/>
     <testCase name="Generators -- simple/two" duration="{duration}"/>
     <testCase name="Nested generators and captured variables" duration="{duration}"/>
+    <testCase name="cat generator" duration="{duration}"/>
+    <testCase name="cat generator/Simple usage" duration="{duration}"/>
+    <testCase name="cat generator/Used in map" duration="{duration}"/>
     <testCase name="strlen3" duration="{duration}"/>
     <testCase name="tables" duration="{duration}"/>
   </file>

tests/SelfTest/Baselines/sonarqube.sw.multi.approved.txt

@@ -144,6 +144,9 @@ at AssertionHandler.tests.cpp:<line number>
     <testCase name="convertToBits" duration="{duration}"/>
   </file>
   <file path="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp">
+    <testCase name="ConcatGenerator" duration="{duration}"/>
+    <testCase name="ConcatGenerator/Cat support single-generator construction" duration="{duration}"/>
+    <testCase name="ConcatGenerator/Iterating over multiple generators" duration="{duration}"/>
     <testCase name="Filter generator throws exception for empty generator" duration="{duration}"/>
     <testCase name="Generators internals" duration="{duration}"/>
     <testCase name="Generators internals/Single value" duration="{duration}"/>
@@ -1241,6 +1244,9 @@ at Generators.tests.cpp:<line number>
     <testCase name="Generators -- simple/one" duration="{duration}"/>
     <testCase name="Generators -- simple/two" duration="{duration}"/>
     <testCase name="Nested generators and captured variables" duration="{duration}"/>
+    <testCase name="cat generator" duration="{duration}"/>
+    <testCase name="cat generator/Simple usage" duration="{duration}"/>
+    <testCase name="cat generator/Used in map" duration="{duration}"/>
     <testCase name="strlen3" duration="{duration}"/>
     <testCase name="tables" duration="{duration}"/>
   </file>

tests/SelfTest/Baselines/tap.sw.approved.txt

@@ -980,6 +980,30 @@ ok {test-number} - matcher.match( 1 ) for: true
 ok {test-number} - first.matchCalled for: true
 # Composed matchers shortcircuit
 ok {test-number} - !second.matchCalled for: true
+# ConcatGenerator
+ok {test-number} - c.get() == 1 for: 1 == 1
+# ConcatGenerator
+ok {test-number} - !(c.next()) for: !false
+# ConcatGenerator
+ok {test-number} - c.get() == i + 1 for: 1 == 1
+# ConcatGenerator
+ok {test-number} - c.next() for: true
+# ConcatGenerator
+ok {test-number} - c.get() == i + 1 for: 2 == 2
+# ConcatGenerator
+ok {test-number} - c.next() for: true
+# ConcatGenerator
+ok {test-number} - c.get() == i + 1 for: 3 == 3
+# ConcatGenerator
+ok {test-number} - c.next() for: true
+# ConcatGenerator
+ok {test-number} - c.get() == i + 1 for: 4 == 4
+# ConcatGenerator
+ok {test-number} - c.next() for: true
+# ConcatGenerator
+ok {test-number} - c.get() == 5 for: 5 == 5
+# ConcatGenerator
+ok {test-number} - !(c.next()) for: !false
 # Contains string matcher
 not ok {test-number} - testStringForMatching(), ContainsSubstring( "not there", Catch::CaseSensitive::No ) for: "this string contains 'abc' as a substring" contains: "not there" (case insensitive)
 # Contains string matcher
@@ -3933,6 +3957,22 @@ ok {test-number} - model.finished == 0 for: 0 == 0
 ok {test-number} - called == 1 for: 1 == 1
 # boolean member
 ok {test-number} - obj.prop != 0 for: 0x<hex digits> != 0
+# cat generator
+ok {test-number} - input < 3 for: 0 < 3
+# cat generator
+ok {test-number} - input < 3 for: 1 < 3
+# cat generator
+ok {test-number} - input < 3 for: 2 < 3
+# cat generator
+ok {test-number} - input % 2 == 0 for: 0 == 0
+# cat generator
+ok {test-number} - input % 2 == 0 for: 0 == 0
+# cat generator
+ok {test-number} - input % 2 == 0 for: 0 == 0
+# cat generator
+ok {test-number} - input % 2 == 0 for: 0 == 0
+# cat generator
+ok {test-number} - input % 2 == 0 for: 0 == 0
 # checkedElse
 ok {test-number} - flag for: true
 # checkedElse
@@ -4641,5 +4681,5 @@ ok {test-number} - q3 == 23. for: 23.0 == 23.0
 ok {test-number} -
 # xmlentitycheck
 ok {test-number} -
-1..2323
+1..2343
 

tests/SelfTest/Baselines/tap.sw.multi.approved.txt

@@ -978,6 +978,30 @@ ok {test-number} - matcher.match( 1 ) for: true
 ok {test-number} - first.matchCalled for: true
 # Composed matchers shortcircuit
 ok {test-number} - !second.matchCalled for: true
+# ConcatGenerator
+ok {test-number} - c.get() == 1 for: 1 == 1
+# ConcatGenerator
+ok {test-number} - !(c.next()) for: !false
+# ConcatGenerator
+ok {test-number} - c.get() == i + 1 for: 1 == 1
+# ConcatGenerator
+ok {test-number} - c.next() for: true
+# ConcatGenerator
+ok {test-number} - c.get() == i + 1 for: 2 == 2
+# ConcatGenerator
+ok {test-number} - c.next() for: true
+# ConcatGenerator
+ok {test-number} - c.get() == i + 1 for: 3 == 3
+# ConcatGenerator
+ok {test-number} - c.next() for: true
+# ConcatGenerator
+ok {test-number} - c.get() == i + 1 for: 4 == 4
+# ConcatGenerator
+ok {test-number} - c.next() for: true
+# ConcatGenerator
+ok {test-number} - c.get() == 5 for: 5 == 5
+# ConcatGenerator
+ok {test-number} - !(c.next()) for: !false
 # Contains string matcher
 not ok {test-number} - testStringForMatching(), ContainsSubstring( "not there", Catch::CaseSensitive::No ) for: "this string contains 'abc' as a substring" contains: "not there" (case insensitive)
 # Contains string matcher
@@ -3926,6 +3950,22 @@ ok {test-number} - model.finished == 0 for: 0 == 0
 ok {test-number} - called == 1 for: 1 == 1
 # boolean member
 ok {test-number} - obj.prop != 0 for: 0x<hex digits> != 0
+# cat generator
+ok {test-number} - input < 3 for: 0 < 3
+# cat generator
+ok {test-number} - input < 3 for: 1 < 3
+# cat generator
+ok {test-number} - input < 3 for: 2 < 3
+# cat generator
+ok {test-number} - input % 2 == 0 for: 0 == 0
+# cat generator
+ok {test-number} - input % 2 == 0 for: 0 == 0
+# cat generator
+ok {test-number} - input % 2 == 0 for: 0 == 0
+# cat generator
+ok {test-number} - input % 2 == 0 for: 0 == 0
+# cat generator
+ok {test-number} - input % 2 == 0 for: 0 == 0
 # checkedElse
 ok {test-number} - flag for: true
 # checkedElse
@@ -4630,5 +4670,5 @@ ok {test-number} - q3 == 23. for: 23.0 == 23.0
 ok {test-number} -
 # xmlentitycheck
 ok {test-number} -
-1..2323
+1..2343
 

tests/SelfTest/Baselines/teamcity.sw.approved.txt

@@ -303,6 +303,8 @@
 ##teamcity[testFinished name='Composed generic matchers shortcircuit' duration="{duration}"]
 ##teamcity[testStarted name='Composed matchers shortcircuit']
 ##teamcity[testFinished name='Composed matchers shortcircuit' duration="{duration}"]
+##teamcity[testStarted name='ConcatGenerator']
+##teamcity[testFinished name='ConcatGenerator' duration="{duration}"]
 ##teamcity[testStarted name='Contains string matcher']
 ##teamcity[testFailed name='Contains string matcher' message='Matchers.tests.cpp:<line number>|n...............................................................................|n|nMatchers.tests.cpp:<line number>|nexpression failed|n  CHECK_THAT( testStringForMatching(), ContainsSubstring( "not there", Catch::CaseSensitive::No ) )|nwith expansion:|n  "this string contains |'abc|' as a substring" contains: "not there" (case insensitive)|n']
 ##teamcity[testFailed name='Contains string matcher' message='Matchers.tests.cpp:<line number>|nexpression failed|n  CHECK_THAT( testStringForMatching(), ContainsSubstring( "STRING" ) )|nwith expansion:|n  "this string contains |'abc|' as a substring" contains: "STRING"|n']
@@ -818,6 +820,8 @@
 ##teamcity[testFinished name='benchmark function call' duration="{duration}"]
 ##teamcity[testStarted name='boolean member']
 ##teamcity[testFinished name='boolean member' duration="{duration}"]
+##teamcity[testStarted name='cat generator']
+##teamcity[testFinished name='cat generator' duration="{duration}"]
 ##teamcity[testStarted name='checkedElse']
 ##teamcity[testFinished name='checkedElse' duration="{duration}"]
 ##teamcity[testStarted name='checkedElse, failing']

tests/SelfTest/Baselines/teamcity.sw.multi.approved.txt

@@ -303,6 +303,8 @@
 ##teamcity[testFinished name='Composed generic matchers shortcircuit' duration="{duration}"]
 ##teamcity[testStarted name='Composed matchers shortcircuit']
 ##teamcity[testFinished name='Composed matchers shortcircuit' duration="{duration}"]
+##teamcity[testStarted name='ConcatGenerator']
+##teamcity[testFinished name='ConcatGenerator' duration="{duration}"]
 ##teamcity[testStarted name='Contains string matcher']
 ##teamcity[testFailed name='Contains string matcher' message='Matchers.tests.cpp:<line number>|n...............................................................................|n|nMatchers.tests.cpp:<line number>|nexpression failed|n  CHECK_THAT( testStringForMatching(), ContainsSubstring( "not there", Catch::CaseSensitive::No ) )|nwith expansion:|n  "this string contains |'abc|' as a substring" contains: "not there" (case insensitive)|n']
 ##teamcity[testFailed name='Contains string matcher' message='Matchers.tests.cpp:<line number>|nexpression failed|n  CHECK_THAT( testStringForMatching(), ContainsSubstring( "STRING" ) )|nwith expansion:|n  "this string contains |'abc|' as a substring" contains: "STRING"|n']
@@ -818,6 +820,8 @@
 ##teamcity[testFinished name='benchmark function call' duration="{duration}"]
 ##teamcity[testStarted name='boolean member']
 ##teamcity[testFinished name='boolean member' duration="{duration}"]
+##teamcity[testStarted name='cat generator']
+##teamcity[testFinished name='cat generator' duration="{duration}"]
 ##teamcity[testStarted name='checkedElse']
 ##teamcity[testFinished name='checkedElse' duration="{duration}"]
 ##teamcity[testStarted name='checkedElse, failing']

tests/SelfTest/Baselines/xml.sw.approved.txt

@@ -4376,6 +4376,111 @@ C
     </Section>
     <OverallResult success="true" skips="0"/>
   </TestCase>
+  <TestCase name="ConcatGenerator" tags="[concat][generators]" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+    <Section name="Cat support single-generator construction" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+        <Original>
+          c.get() == 1
+        </Original>
+        <Expanded>
+          1 == 1
+        </Expanded>
+      </Expression>
+      <Expression success="true" type="REQUIRE_FALSE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+        <Original>
+          !(c.next())
+        </Original>
+        <Expanded>
+          !false
+        </Expanded>
+      </Expression>
+      <OverallResults successes="2" failures="0" expectedFailures="0" skipped="false"/>
+    </Section>
+    <Section name="Iterating over multiple generators" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+        <Original>
+          c.get() == i + 1
+        </Original>
+        <Expanded>
+          1 == 1
+        </Expanded>
+      </Expression>
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+        <Original>
+          c.next()
+        </Original>
+        <Expanded>
+          true
+        </Expanded>
+      </Expression>
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+        <Original>
+          c.get() == i + 1
+        </Original>
+        <Expanded>
+          2 == 2
+        </Expanded>
+      </Expression>
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+        <Original>
+          c.next()
+        </Original>
+        <Expanded>
+          true
+        </Expanded>
+      </Expression>
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+        <Original>
+          c.get() == i + 1
+        </Original>
+        <Expanded>
+          3 == 3
+        </Expanded>
+      </Expression>
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+        <Original>
+          c.next()
+        </Original>
+        <Expanded>
+          true
+        </Expanded>
+      </Expression>
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+        <Original>
+          c.get() == i + 1
+        </Original>
+        <Expanded>
+          4 == 4
+        </Expanded>
+      </Expression>
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+        <Original>
+          c.next()
+        </Original>
+        <Expanded>
+          true
+        </Expanded>
+      </Expression>
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+        <Original>
+          c.get() == 5
+        </Original>
+        <Expanded>
+          5 == 5
+        </Expanded>
+      </Expression>
+      <Expression success="true" type="REQUIRE_FALSE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+        <Original>
+          !(c.next())
+        </Original>
+        <Expanded>
+          !false
+        </Expanded>
+      </Expression>
+      <OverallResults successes="10" failures="0" expectedFailures="0" skipped="false"/>
+    </Section>
+    <OverallResult success="true" skips="0"/>
+  </TestCase>
   <TestCase name="Contains string matcher" tags="[.][failing][matchers]" filename="tests/<exe-name>/UsageTests/Matchers.tests.cpp" >
     <Expression success="false" type="CHECK_THAT" filename="tests/<exe-name>/UsageTests/Matchers.tests.cpp" >
       <Original>
@@ -19155,6 +19260,97 @@ Approx( 1.23999999999999999 )
     </Expression>
     <OverallResult success="true" skips="0"/>
   </TestCase>
+  <TestCase name="cat generator" tags="[concat][generators]" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+    <Section name="Simple usage" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Original>
+          input &lt; 3
+        </Original>
+        <Expanded>
+          0 &lt; 3
+        </Expanded>
+      </Expression>
+      <OverallResults successes="1" failures="0" expectedFailures="0" skipped="false"/>
+    </Section>
+    <Section name="Simple usage" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Original>
+          input &lt; 3
+        </Original>
+        <Expanded>
+          1 &lt; 3
+        </Expanded>
+      </Expression>
+      <OverallResults successes="1" failures="0" expectedFailures="0" skipped="false"/>
+    </Section>
+    <Section name="Simple usage" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Original>
+          input &lt; 3
+        </Original>
+        <Expanded>
+          2 &lt; 3
+        </Expanded>
+      </Expression>
+      <OverallResults successes="1" failures="0" expectedFailures="0" skipped="false"/>
+    </Section>
+    <Section name="Used in map" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Original>
+          input % 2 == 0
+        </Original>
+        <Expanded>
+          0 == 0
+        </Expanded>
+      </Expression>
+      <OverallResults successes="1" failures="0" expectedFailures="0" skipped="false"/>
+    </Section>
+    <Section name="Used in map" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Original>
+          input % 2 == 0
+        </Original>
+        <Expanded>
+          0 == 0
+        </Expanded>
+      </Expression>
+      <OverallResults successes="1" failures="0" expectedFailures="0" skipped="false"/>
+    </Section>
+    <Section name="Used in map" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Original>
+          input % 2 == 0
+        </Original>
+        <Expanded>
+          0 == 0
+        </Expanded>
+      </Expression>
+      <OverallResults successes="1" failures="0" expectedFailures="0" skipped="false"/>
+    </Section>
+    <Section name="Used in map" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Original>
+          input % 2 == 0
+        </Original>
+        <Expanded>
+          0 == 0
+        </Expanded>
+      </Expression>
+      <OverallResults successes="1" failures="0" expectedFailures="0" skipped="false"/>
+    </Section>
+    <Section name="Used in map" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Original>
+          input % 2 == 0
+        </Original>
+        <Expanded>
+          0 == 0
+        </Expanded>
+      </Expression>
+      <OverallResults successes="1" failures="0" expectedFailures="0" skipped="false"/>
+    </Section>
+    <OverallResult success="true" skips="0"/>
+  </TestCase>
   <TestCase name="checkedElse" filename="tests/<exe-name>/UsageTests/Misc.tests.cpp" >
     <Expression success="true" type="CHECKED_ELSE" filename="tests/<exe-name>/UsageTests/Misc.tests.cpp" >
       <Original>
@@ -22416,6 +22612,6 @@ Approx( -1.95996398454005449 )
     </Section>
     <OverallResult success="true" skips="0"/>
   </TestCase>
-  <OverallResults successes="2110" failures="158" expectedFailures="43" skips="12"/>
-  <OverallResultsCases successes="317" failures="96" expectedFailures="18" skips="6"/>
+  <OverallResults successes="2130" failures="158" expectedFailures="43" skips="12"/>
+  <OverallResultsCases successes="319" failures="96" expectedFailures="18" skips="6"/>
 </Catch2TestRun>

tests/SelfTest/Baselines/xml.sw.multi.approved.txt

@@ -4376,6 +4376,111 @@ C
     </Section>
     <OverallResult success="true" skips="0"/>
   </TestCase>
+  <TestCase name="ConcatGenerator" tags="[concat][generators]" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+    <Section name="Cat support single-generator construction" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+        <Original>
+          c.get() == 1
+        </Original>
+        <Expanded>
+          1 == 1
+        </Expanded>
+      </Expression>
+      <Expression success="true" type="REQUIRE_FALSE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+        <Original>
+          !(c.next())
+        </Original>
+        <Expanded>
+          !false
+        </Expanded>
+      </Expression>
+      <OverallResults successes="2" failures="0" expectedFailures="0" skipped="false"/>
+    </Section>
+    <Section name="Iterating over multiple generators" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+        <Original>
+          c.get() == i + 1
+        </Original>
+        <Expanded>
+          1 == 1
+        </Expanded>
+      </Expression>
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+        <Original>
+          c.next()
+        </Original>
+        <Expanded>
+          true
+        </Expanded>
+      </Expression>
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+        <Original>
+          c.get() == i + 1
+        </Original>
+        <Expanded>
+          2 == 2
+        </Expanded>
+      </Expression>
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+        <Original>
+          c.next()
+        </Original>
+        <Expanded>
+          true
+        </Expanded>
+      </Expression>
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+        <Original>
+          c.get() == i + 1
+        </Original>
+        <Expanded>
+          3 == 3
+        </Expanded>
+      </Expression>
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+        <Original>
+          c.next()
+        </Original>
+        <Expanded>
+          true
+        </Expanded>
+      </Expression>
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+        <Original>
+          c.get() == i + 1
+        </Original>
+        <Expanded>
+          4 == 4
+        </Expanded>
+      </Expression>
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+        <Original>
+          c.next()
+        </Original>
+        <Expanded>
+          true
+        </Expanded>
+      </Expression>
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+        <Original>
+          c.get() == 5
+        </Original>
+        <Expanded>
+          5 == 5
+        </Expanded>
+      </Expression>
+      <Expression success="true" type="REQUIRE_FALSE" filename="tests/<exe-name>/IntrospectiveTests/GeneratorsImpl.tests.cpp" >
+        <Original>
+          !(c.next())
+        </Original>
+        <Expanded>
+          !false
+        </Expanded>
+      </Expression>
+      <OverallResults successes="10" failures="0" expectedFailures="0" skipped="false"/>
+    </Section>
+    <OverallResult success="true" skips="0"/>
+  </TestCase>
   <TestCase name="Contains string matcher" tags="[.][failing][matchers]" filename="tests/<exe-name>/UsageTests/Matchers.tests.cpp" >
     <Expression success="false" type="CHECK_THAT" filename="tests/<exe-name>/UsageTests/Matchers.tests.cpp" >
       <Original>
@@ -19155,6 +19260,97 @@ Approx( 1.23999999999999999 )
     </Expression>
     <OverallResult success="true" skips="0"/>
   </TestCase>
+  <TestCase name="cat generator" tags="[concat][generators]" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+    <Section name="Simple usage" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Original>
+          input &lt; 3
+        </Original>
+        <Expanded>
+          0 &lt; 3
+        </Expanded>
+      </Expression>
+      <OverallResults successes="1" failures="0" expectedFailures="0" skipped="false"/>
+    </Section>
+    <Section name="Simple usage" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Original>
+          input &lt; 3
+        </Original>
+        <Expanded>
+          1 &lt; 3
+        </Expanded>
+      </Expression>
+      <OverallResults successes="1" failures="0" expectedFailures="0" skipped="false"/>
+    </Section>
+    <Section name="Simple usage" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Original>
+          input &lt; 3
+        </Original>
+        <Expanded>
+          2 &lt; 3
+        </Expanded>
+      </Expression>
+      <OverallResults successes="1" failures="0" expectedFailures="0" skipped="false"/>
+    </Section>
+    <Section name="Used in map" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Original>
+          input % 2 == 0
+        </Original>
+        <Expanded>
+          0 == 0
+        </Expanded>
+      </Expression>
+      <OverallResults successes="1" failures="0" expectedFailures="0" skipped="false"/>
+    </Section>
+    <Section name="Used in map" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Original>
+          input % 2 == 0
+        </Original>
+        <Expanded>
+          0 == 0
+        </Expanded>
+      </Expression>
+      <OverallResults successes="1" failures="0" expectedFailures="0" skipped="false"/>
+    </Section>
+    <Section name="Used in map" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Original>
+          input % 2 == 0
+        </Original>
+        <Expanded>
+          0 == 0
+        </Expanded>
+      </Expression>
+      <OverallResults successes="1" failures="0" expectedFailures="0" skipped="false"/>
+    </Section>
+    <Section name="Used in map" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Original>
+          input % 2 == 0
+        </Original>
+        <Expanded>
+          0 == 0
+        </Expanded>
+      </Expression>
+      <OverallResults successes="1" failures="0" expectedFailures="0" skipped="false"/>
+    </Section>
+    <Section name="Used in map" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+      <Expression success="true" type="REQUIRE" filename="tests/<exe-name>/UsageTests/Generators.tests.cpp" >
+        <Original>
+          input % 2 == 0
+        </Original>
+        <Expanded>
+          0 == 0
+        </Expanded>
+      </Expression>
+      <OverallResults successes="1" failures="0" expectedFailures="0" skipped="false"/>
+    </Section>
+    <OverallResult success="true" skips="0"/>
+  </TestCase>
   <TestCase name="checkedElse" filename="tests/<exe-name>/UsageTests/Misc.tests.cpp" >
     <Expression success="true" type="CHECKED_ELSE" filename="tests/<exe-name>/UsageTests/Misc.tests.cpp" >
       <Original>
@@ -22415,6 +22611,6 @@ Approx( -1.95996398454005449 )
     </Section>
     <OverallResult success="true" skips="0"/>
   </TestCase>
-  <OverallResults successes="2110" failures="158" expectedFailures="43" skips="12"/>
-  <OverallResultsCases successes="317" failures="96" expectedFailures="18" skips="6"/>
+  <OverallResults successes="2130" failures="158" expectedFailures="43" skips="12"/>
+  <OverallResultsCases successes="319" failures="96" expectedFailures="18" skips="6"/>
 </Catch2TestRun>

tests/SelfTest/IntrospectiveTests/GeneratorsImpl.tests.cpp

@@ -85,7 +85,7 @@ TEST_CASE("Generators internals", "[generators][internals]") {
                 filter([](int) { return false; }, values({ 1, 2, 3 })),
                 Catch::GeneratorException);
         }
-        
+
         // Non-trivial usage
         SECTION("Out-of-line predicates are copied into the generator") {
             auto evilNumber = Catch::Detail::make_unique<int>(2);
@@ -586,3 +586,21 @@ TEST_CASE("from_range(container) supports ADL begin/end and arrays", "[generator
     }
 
 }
+
+TEST_CASE( "ConcatGenerator", "[generators][concat]" ) {
+    using namespace Catch::Generators;
+    SECTION( "Cat support single-generator construction" ) {
+        ConcatGenerator<int> c( value( 1 ) );
+        REQUIRE( c.get() == 1 );
+        REQUIRE_FALSE( c.next() );
+    }
+    SECTION( "Iterating over multiple generators" ) {
+        ConcatGenerator<int> c( value( 1 ), values( { 2, 3, 4 } ), value( 5 ) );
+        for ( int i = 0; i < 4; ++i ) {
+            REQUIRE( c.get() == i + 1 );
+            REQUIRE( c.next() );
+        }
+        REQUIRE( c.get() == 5 );
+        REQUIRE_FALSE( c.next() );
+    }
+}

tests/SelfTest/UsageTests/Generators.tests.cpp

@@ -321,3 +321,16 @@ TEST_CASE( "GENERATE can combine literals and generators", "[generators]" ) {
                                      random( -100, 100 ) ) ) );
     REQUIRE( i % 2 == 0 );
 }
+
+TEST_CASE( "cat generator", "[generators][concat]" ) {
+    SECTION("Simple usage") {
+        const int input = GENERATE( cat( value( 0 ) ), cat( value( 1 ), value( 2 ) ) );
+        REQUIRE( input < 3 );
+    }
+    SECTION( "Used in map" ) {
+        const int input = GENERATE(
+            map( []( int i ) { return i * 2; },
+                 cat( value( 1 ), take( 4, random( 10, 10'000'000 ) ) ) ) );
+        REQUIRE( input % 2 == 0 );
+    }
+}