build: Add build target to generate coverage report

This adds a 'make coverage' option to conveniently summarize test
coverage. If lcov is installed, it will also automatically generate
the HTML summary.

Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>

1 files changed, 94 insertions, 0 deletions

diff --git a/cmake/utils/GenCoverage.cmake b/cmake/utils/GenCoverage.cmake
new file mode 100644
index 00000000..65f5d8ba
--- /dev/null
+++ b/cmake/utils/GenCoverage.cmake
@@ -0,0 +1,94 @@
+# Creates the coverage target for test coverage analysis
+# Requires HAVE_GCOV to be set (from dependencies/gcov.cmake)
+# Uses HAVE_LCOV for optional HTML generation (from dependencies/lcov.cmake)
+
+# Filter patterns for lcov --remove
+set(LCOV_FILTERS '*_test.c' '*.h')
+
+# Ignore inconsistent coverage: legitimate gaps in error paths and
+# edge cases that are difficult to exercise in unit tests.
+function(get_html_coverage_commands OUTPUT_VAR)
+  if(HAVE_LCOV)
+    set(COMMANDS
+      COMMAND ${LCOV_PATH}
+        --capture --directory .
+        --output-file coverage.info
+        > /dev/null 2>&1
+      COMMAND ${LCOV_PATH}
+        --remove coverage.info ${LCOV_FILTERS}
+        --output-file coverage_filtered.info
+        --ignore-errors inconsistent
+        > /dev/null 2>&1
+      COMMAND ${GENHTML_PATH}
+        coverage_filtered.info
+        --output-directory coverage_html
+        > /dev/null 2>&1
+      COMMAND ${CMAKE_COMMAND} -E echo ""
+      COMMAND ${CMAKE_COMMAND} -E echo "HTML report: ${CMAKE_BINARY_DIR}/coverage_html/index.html"
+      COMMAND ${CMAKE_COMMAND} -E echo ""
+    )
+    set(${OUTPUT_VAR} "${COMMANDS}" PARENT_SCOPE)
+  else()
+    set(${OUTPUT_VAR} "" PARENT_SCOPE)
+  endif()
+endfunction()
+
+function(create_informational_target)
+  # MESSAGE lines are passed as ARGV, last arg is COMMENT
+  list(LENGTH ARGV NUM_ARGS)
+  math(EXPR COMMENT_IDX "${NUM_ARGS} - 1")
+  list(GET ARGV ${COMMENT_IDX} COMMENT_TEXT)
+
+  # Build command list
+  set(COMMANDS
+    COMMAND ${CMAKE_COMMAND} -E echo ""
+  )
+  foreach(i RANGE 0 ${COMMENT_IDX})
+    if(NOT i EQUAL ${COMMENT_IDX})
+      list(GET ARGV ${i} LINE)
+      list(APPEND COMMANDS COMMAND ${CMAKE_COMMAND} -E echo "${LINE}")
+    endif()
+  endforeach()
+  list(APPEND COMMANDS COMMAND ${CMAKE_COMMAND} -E echo "")
+
+  add_custom_target(coverage
+    ${COMMANDS}
+    COMMENT "${COMMENT_TEXT}"
+  )
+endfunction()
+
+macro(create_coverage_target)
+  if(HAVE_GCOV AND ENABLE_COVERAGE)
+    get_html_coverage_commands(HTML_COVERAGE_COMMANDS)
+
+    add_custom_target(coverage
+      COMMAND ${CMAKE_CTEST_COMMAND} -D ExperimentalStart > /dev/null 2>&1
+      COMMAND ${CMAKE_CTEST_COMMAND} -D ExperimentalConfigure > /dev/null 2>&1
+      COMMAND ${CMAKE_CTEST_COMMAND} -D ExperimentalBuild > /dev/null 2>&1
+      COMMAND ${CMAKE_CTEST_COMMAND} -D ExperimentalTest > /dev/null 2>&1
+      COMMAND ${CMAKE_CTEST_COMMAND} -D ExperimentalCoverage > /dev/null 2>&1
+      COMMAND ${CMAKE_COMMAND}
+        -DPROJECT_SOURCE_DIR=${CMAKE_SOURCE_DIR}
+        -DPROJECT_BINARY_DIR=${CMAKE_BINARY_DIR}
+        -P ${CMAKE_SOURCE_DIR}/cmake/utils/PrintCoverage.cmake
+      ${HTML_COVERAGE_COMMANDS}
+      WORKING_DIRECTORY ${CMAKE_BINARY_DIR}
+      DEPENDS build_tests
+      COMMENT "Running tests with coverage analysis using CTest"
+    )
+  elseif(HAVE_GCOV)
+    create_informational_target(
+      "Coverage is currently disabled"
+      "To enable coverage analysis, reconfigure with"
+      "  cmake -DDISABLE_COVERAGE=OFF .."
+      "Coverage disabled"
+    )
+    message(STATUS "Coverage disabled. Use 'make coverage' for instructions to enable.")
+  else()
+    create_informational_target(
+      "Coverage analysis is not available"
+      "Install gcov to enable coverage support"
+      "Coverage not available"
+    )
+  endif()
+endmacro()