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, 120 insertions, 0 deletions

diff --git a/cmake/utils/ParseCoverage.cmake b/cmake/utils/ParseCoverage.cmake
new file mode 100644
index 00000000..0bbed0de
--- /dev/null
+++ b/cmake/utils/ParseCoverage.cmake
@@ -0,0 +1,120 @@
+# Parse CTest Coverage.xml file and extract structured coverage data.
+#
+# Sets in PARENT_SCOPE:
+#   LOC_TESTED, LOC_UNTESTED - Overall metrics
+#   FILE_COVERAGE_LIST - "path|name|tested|untested|total|percent" entries
+#   COVERED_FILES - Absolute paths of covered files
+
+# Regex building blocks
+set(R_NUMBER "[0-9]+")
+set(R_NON_TAG "[^<]*")
+set(R_NON_BRACKET "[^>]*")
+set(R_NON_QUOTE "[^\"]+")
+
+# XML element patterns
+set(R_LOC_TESTED_ELEM "<LOCTested>(${R_NUMBER})</LOCTested>")
+set(R_LOC_TESTED_SKIP "<LOCTested>${R_NUMBER}</LOCTested>")
+set(R_LOC_UNTESTED_ELEM "<LOCUntested>(${R_NUMBER})</LOCUntested>")
+set(R_LOC_UNTESTED_CAP "<LOCUnTested>(${R_NUMBER})</LOCUnTested>")
+
+# Regex patterns for XML parsing
+set(REGEX_LOC_TESTED "</File>${R_NON_TAG}${R_LOC_TESTED_ELEM}")
+set(REGEX_LOC_UNTESTED "</File>${R_NON_TAG}${R_LOC_TESTED_SKIP}${R_NON_TAG}${R_LOC_UNTESTED_ELEM}")
+set(REGEX_FILE_ENTRY "<File${R_NON_BRACKET}Name=\"(${R_NON_QUOTE})\"${R_NON_BRACKET}>${R_NON_TAG}${R_LOC_TESTED_ELEM}${R_NON_TAG}${R_LOC_UNTESTED_CAP}")
+
+# Regex patterns for filtering
+set(REGEX_TEST_FILE "test")
+set(REGEX_TEST_DIR "/tests/")
+set(REGEX_PROTOBUF_C "\\.pb-c\\.c$")
+set(REGEX_PROTOBUF_ALT "\\.pb\\.c$")
+set(REGEX_DOTSLASH_SRC "^\\.\\/src\\/")
+
+function(should_skip_file FILE_PATH OUTPUT_VAR)
+  if(FILE_PATH MATCHES "${REGEX_TEST_FILE}" OR FILE_PATH MATCHES "${REGEX_TEST_DIR}" OR
+     FILE_PATH MATCHES "${REGEX_PROTOBUF_C}" OR FILE_PATH MATCHES "${REGEX_PROTOBUF_ALT}")
+    set(${OUTPUT_VAR} TRUE PARENT_SCOPE)
+  else()
+    set(${OUTPUT_VAR} FALSE PARENT_SCOPE)
+  endif()
+endfunction()
+
+function(normalize_coverage_path FILE_PATH PROJECT_SOURCE_DIR OUTPUT_VAR)
+  if(NOT IS_ABSOLUTE "${FILE_PATH}")
+    string(REGEX REPLACE "${REGEX_DOTSLASH_SRC}" "src/" FILE_PATH "${FILE_PATH}")
+    get_filename_component(FILE_PATH "${PROJECT_SOURCE_DIR}/${FILE_PATH}" ABSOLUTE)
+  endif()
+  set(${OUTPUT_VAR} "${FILE_PATH}" PARENT_SCOPE)
+endfunction()
+
+function(extract_xml_attribute XML_STRING ATTRIBUTE OUTPUT_VAR)
+  string(REGEX MATCH "${ATTRIBUTE}=\"([^\"]+)\"" _ "${XML_STRING}")
+  set(${OUTPUT_VAR} "${CMAKE_MATCH_1}" PARENT_SCOPE)
+endfunction()
+
+function(extract_xml_element XML_STRING ELEMENT OUTPUT_VAR)
+  string(REGEX MATCH "<${ELEMENT}>([^<]+)</${ELEMENT}>" _ "${XML_STRING}")
+  set(${OUTPUT_VAR} "${CMAKE_MATCH_1}" PARENT_SCOPE)
+endfunction()
+
+function(build_coverage_entry PATH NAME TESTED UNTESTED OUTPUT_VAR)
+  math(EXPR TOTAL "${TESTED} + ${UNTESTED}")
+  if(NOT TOTAL GREATER 0)
+    set(${OUTPUT_VAR} "" PARENT_SCOPE)
+    return()
+  endif()
+  math(EXPR PERCENT "(${TESTED} * 100) / ${TOTAL}")
+  set(${OUTPUT_VAR} "${PATH}|${NAME}|${TESTED}|${UNTESTED}|${TOTAL}|${PERCENT}" PARENT_SCOPE)
+endfunction()
+
+function(parse_coverage_xml COVERAGE_FILE PROJECT_SOURCE_DIR)
+  if(NOT EXISTS "${COVERAGE_FILE}")
+    return()
+  endif()
+
+  file(READ "${COVERAGE_FILE}" COVERAGE_XML)
+
+  string(REGEX MATCH "${REGEX_LOC_TESTED}" _ "${COVERAGE_XML}")
+  set(TESTED "${CMAKE_MATCH_1}")
+
+  string(REGEX MATCH "${REGEX_LOC_UNTESTED}" _ "${COVERAGE_XML}")
+  set(UNTESTED "${CMAKE_MATCH_1}")
+
+  if(NOT TESTED OR NOT UNTESTED)
+    return()
+  endif()
+
+  string(REGEX MATCHALL "${REGEX_FILE_ENTRY}" FILE_MATCHES "${COVERAGE_XML}")
+
+  set(COVERED_LIST "")
+  set(COVERAGE_DATA "")
+
+  foreach(MATCH ${FILE_MATCHES})
+    extract_xml_attribute("${MATCH}" "FullPath" PATH)
+    extract_xml_attribute("${MATCH}" "Name" NAME)
+
+    should_skip_file("${PATH}" SKIP)
+    if(SKIP)
+      continue()
+    endif()
+
+    normalize_coverage_path("${PATH}" "${PROJECT_SOURCE_DIR}" ABS_PATH)
+    list(APPEND COVERED_LIST "${ABS_PATH}")
+
+    extract_xml_element("${MATCH}" "LOCTested" TESTED_LINES)
+    extract_xml_element("${MATCH}" "LOCUnTested" UNTESTED_LINES)
+
+    if(NOT TESTED_LINES OR NOT UNTESTED_LINES)
+      continue()
+    endif()
+
+    build_coverage_entry("${PATH}" "${NAME}" "${TESTED_LINES}" "${UNTESTED_LINES}" ENTRY)
+    if(ENTRY)
+      list(APPEND COVERAGE_DATA "${ENTRY}")
+    endif()
+  endforeach()
+
+  set(LOC_TESTED "${TESTED}" PARENT_SCOPE)
+  set(LOC_UNTESTED "${UNTESTED}" PARENT_SCOPE)
+  set(FILE_COVERAGE_LIST "${COVERAGE_DATA}" PARENT_SCOPE)
+  set(COVERED_FILES "${COVERED_LIST}" PARENT_SCOPE)
+endfunction()