Add coverage collection script for appveyor

Dependencies:
  - Choco
  - Powershell

.appveyor.yml

@@ -113,6 +113,13 @@ environment:
       B2_CXXSTD: 03,11,14,1z
       B2_TOOLSET: gcc
 
+    - FLAVOR: CodeCov (VS 2019)
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
+      B2_CXXFLAGS: -permissive-
+      B2_CXXSTD: 14
+      B2_TOOLSET: msvc-14.2
+      COVERAGE: true
+
 install:
   - git clone --depth 1 https://github.com/boostorg/boost-ci.git C:\boost-ci-cloned
   # Copy ci folder if not testing Boost.CI
@@ -123,3 +130,9 @@ install:
 build: off
 
 test_script: ci\build.bat
+
+for:
+  # Superproject CMake build
+  - matrix:
+      only: [COVERAGE: true]
+    test_script: [ps: ci\codecov.ps1]

ci/codecov.ps1

@@ -0,0 +1,68 @@
+# Copyright 2019 - 2021 Alexander Grund
+# Distributed under the Boost Software License, Version 1.0.
+# (See accompanying file LICENSE or copy at http://boost.org/LICENSE_1_0.txt)
+
+$ErrorActionPreference = "Stop"
+
+$scriptPath = split-path $MyInvocation.MyCommand.Path
+
+# Install coverage collector (Similar to LCov)
+choco install opencppcoverage
+$env:Path += ";C:\Program Files\OpenCppCoverage"
+
+# Install uploader
+Invoke-WebRequest -Uri https://uploader.codecov.io/latest/windows/codecov.exe -Outfile codecov.exe
+
+# Verify integrity
+if (Get-Command "gpg.exe" -ErrorAction SilentlyContinue){
+    $ProgressPreference = 'SilentlyContinue'
+    Invoke-WebRequest -Uri https://keybase.io/codecovsecurity/pgp_keys.asc -OutFile codecov.asc
+    Invoke-WebRequest -Uri https://uploader.codecov.io/latest/windows/codecov.exe.SHA256SUM -Outfile codecov.exe.SHA256SUM
+    Invoke-WebRequest -Uri https://uploader.codecov.io/latest/windows/codecov.exe.SHA256SUM.sig -Outfile codecov.exe.SHA256SUM.sig
+
+    $ErrorActionPreference = "Continue"
+    gpg.exe --import codecov.asc
+    if ($LASTEXITCODE -ne 0) { Throw "Importing the key failed." }
+    gpg.exe --verify codecov.exe.SHA256SUM.sig codecov.exe.SHA256SUM
+    if ($LASTEXITCODE -ne 0) { Throw "Signature validation of the SHASUM failed." }
+    If ($(Compare-Object -ReferenceObject  $(($(certUtil -hashfile codecov.exe SHA256)[1], "codecov.exe") -join "  ") -DifferenceObject $(Get-Content codecov.exe.SHA256SUM)).length -eq 0) { 
+        echo "SHASUM verified"
+    } Else {
+        exit 1
+    }
+}
+    
+# Run build with coverage collection
+$env:B2_VARIANT = "debug"
+
+# Use a temporary folder to avoid codecov picking up wrong files
+mkdir __out
+
+# Build command to collect coverage
+$cmd = 'OpenCppCoverage.exe --export_type cobertura:__out/cobertura.xml --modules "{0}" ' -f ${env:BOOST_ROOT}
+# Include own headers (relocated to boost\*)
+$cmd += (Get-ChildItem -Name "${env:BOOST_CI_SRC_FOLDER}\include\boost").ForEach({'--sources "boost\{0}"' -f $_}) -join " "
+# Include own cpp files
+$cmd += " --sources ${env:BOOST_ROOT}\libs\${env:SELF} "
+$exclusions = @(
+  # Lines marked with LCov or coverity exclusion comments
+  '.*// LCOV_EXCL_LINE'
+  '.*// coverity\[dead_error_line\]'
+  # Lines containing only braces
+  '\s*[{}]*\s*'
+  # Lines containing only else (and opt. braces)
+  '\s*(\} )?else( \{)?\s*'
+)
+$cmd += $exclusions.ForEach({"--excluded_line_regex '{0}'" -f $_}) -join " "
+# Cover all subprocess of the build script (-> b2 -> test binary)
+$cmd += "--cover_children -- cmd.exe /c $scriptPath/build.bat"
+
+# Print generated command and run
+$cmd
+Invoke-Expression $cmd
+
+if ($LASTEXITCODE -ne 0) { Throw "Coverage collection failed." }
+
+# Upload
+./codecov.exe --name Appveyor --env APPVEYOR_BUILD_WORKER_IMAGE --verbose --nonZero --dir __out --rootDir "${env:BOOST_CI_SRC_FOLDER}"
+if ($LASTEXITCODE -ne 0) { Throw "Upload of coverage data failed." }