Added code coverage documentation.

README_DOC.md

@@ -1,4 +1,5 @@
 ## Plugin Documentation
 + [Technical details of Hydra for Maya](./doc/mayaHydraDetails.md)
 + [Selection in Hydra for Maya](./doc/mayaHydraSelection.md)
-+ [Selection Highlighting Architecture](./doc/selectionHighlightingArchitecture.md)
++ [Selection Highlighting Architecture](./doc/selectionHighlightingArchitecture.md)
++ [Code Coverage Instructions](./doc/codeCoverageInstructions.md)

doc/codeCoverageInstructions.md

@@ -0,0 +1,71 @@
+# Code Coverage For Windows
+
+Maya-hydra has support for obtaining code coverage on Windows platforms.
+
+The support uses two main tools: Clang for the compilation of maya-hydra and the LLVM toolset for the parsing of code coverage
+information and the generation of a code coverage report.
+
+## Prerequisites
+
+To install Clang and the LLVM toolset, you can install an optional module with Visual Studio.  Refer to these instructions: [Install Clang and LLVM Toolset](https://learn.microsoft.com/en-us/cpp/build/clang-support-msbuild?view=msvc-170)
+
+## Documentation References
+- [llvm-profdata and llvm-cov show](https://llvm.org/docs/CommandGuide/llvm-cov.html)
+- [Compiling clang with coverage](https://clang.llvm.org/docs/SourceBasedCodeCoverage.html)
+
+## Building the Coverage Variant
+
+The maya-hydra build has a Coverage variant that can be used with the following stages: clean,build,install,test (note that the test stage depends on the install stage).  Clang is used with code coverage instrumentation flags enabled (-fprofile-instr-generate -fcoverage-mapping) so that when tests are run after a successful install stage, code coverage data files will be generated.
+
+To build the coverage variant you can run:
+
+```
+python build.py --generator=Ninja --stages clean,configure,build,install --maya-location <maya_location> --build-coverage --pxrusd-location <pxrusd_location> --devkit-location <devkit_location> --build-args="-DPYTHON_INCLUDE_DIR=<python_include_dir>,-DPython_EXECUTABLE=<python_executable>,-DPYTHON_LIBRARIES=<python_libraries>,-DBUILD_WITH_PYTHON_3=ON,-DBUILD_WITH_PYTHON_3_VERSION=<version_of_python>,-DQT_VERSION=6.5.0,-DCMAKE_WANT_MATERIALX_BUILD=ON,-DCMAKE_PREFIX_PATH=<cmake_prefix_path>" <installation_location>
+```
+
+The --build-coverage flag indicates that the variant to be built is the Coverage variant. 
+
+## Running Tests and Getting Raw Coverage Information
+
+To run tests and generate code coverage information using the Coverage build, run:
+
+```
+python build.py --generator=Ninja --stages test --maya-location <maya_location> --build-coverage --pxrusd-location <pxrusd_location> --devkit-location <devkit_location> --build-args="-DPYTHON_INCLUDE_DIR=<python_include_dir>,-DPython_EXECUTABLE=<python_executable>,-DPYTHON_LIBRARIES=<python_libraries>,-DBUILD_WITH_PYTHON_3=ON,-DBUILD_WITH_PYTHON_3_VERSION=<version_of_python>,-DQT_VERSION=6.5.0,-DCMAKE_WANT_MATERIALX_BUILD=ON,-DCMAKE_PREFIX_PATH=<cmake_prefix_path>" <installation_location>
+```
+
+After running tests, there will be raw coverage information files generated that are have a file extension of .profraw. 
+
+## Parsing Coverage Information and Report
+
+To parse the coverage information, two tools from the LLVM toolset are used: llvm-profdata and llvm-cov show. 
+llvm-profdata parses and merges all of the raw coverage information files into a single file that has a file extension of .profdata.
+llvm-cov show uses this created file to generate an HTML report of the coverage of the maya-hydra plugin. 
+
+There is no build stage in maya-hydra that can automatically run this step of collecting coverage information and creating a report.  To complete this step manually
+here are the instructions.
+
+To run llvm-profdata and parse all of the coverage information into a single file, run:
+
+```
+llvm-profdata merge -sparse -o '<profdata_file_name>' '<profraw_file_location(s)' 
+```
+
+Note:
+- Multiple profraw file locations can be specified, each of which should be separated by a space after the profraw file name
+- The profdata file name must end with the file extension .profdata
+
+To run llvm-cov show and to generate an HTML report containing code coverage information, run:
+
+```
+llvm-cov show -instr-profile=<profdata_file_location> <mayaHydraLib.dll_location> -object=mayaHydra.mll_location -object=flowViewport.dll_location -show-branches=count -show-regions --ignore-filename-regex='artifactory\\.*' -format=html -output-dir=<output_dir_name>'
+```
+
+Note:
+- -instr-profile refers to the previously generated profdata file, which contains all code coverage information
+- --ignore-filename-regex removes any files starting with artifactory from the report
+
+## Viewing Results
+
+Go to the output directory from the llvm-cov show command and open the index.html file. Any lines that are uncovered are red. Lines that are covered have no highlighting around them.
+
+