Add a "make verify_coverage" target generation coverage info.

Use lcov/gcov to gather coverage info for the tests (Only works with gcc/clang and make).

cmake -DEVENT__COVERAGE=1 -DCMAKE_BUILD_TYPE=Debug ..
make
make verify_coverage

Current coverage (run on debian):
Line coverage 79.1 %	10231 / 12939
Function coverage 86.1 %	933 / 1083

2 files changed, 189 insertions, 0 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 38ffb6ca..aa35da6f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -36,6 +36,7 @@ option(EVENT__DISABLE_BENCHMARK "Defines if libevent should build without the be
 option(EVENT__DISABLE_TESTS "If tests should be compiled or not" OFF)
 option(EVENT__DISABLE_REGRESS "Disable the regress tests" OFF)
 option(EVENT__FORCE_KQUEUE_CHECK "When crosscompiling forces running a test program that verifies that Kqueue works with pipes. Note that this requires you to manually run the test program on the the cross compilation target to verify that it works. See cmake documentation for try_run for more details" OFF)
+option(EVENT__COVERAGE "Enable running gcov to get a test coverage report (only works with GCC/CLang). Make sure to enable -DCMAKE_BUILD_TYPE=Debug as well." OFF)
 # TODO: Add --enable-verbose-debug, verbose debug logging
 # TODO: Add --disable-largefile     omit support for large files
 
@@ -60,6 +61,22 @@ include(CheckPrototypeDefinition)
 
 include(FindZLIB)    # -> HAVE_LIBZ
 
+# Setup compiler flags for coverage.
+if (EVENT__COVERAGE)
+    if(NOT CMAKE_COMPILER_IS_GNUCXX)
+        if (NOT "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")
+            message(FATAL_ERROR "Compiler is not GNU gcc! Aborting... You can set this on the command line using CC=/usr/bin/gcc CXX=/usr/bin/g++ cmake <options> ..")
+        endif()
+    endif()
+
+    if(NOT CMAKE_BUILD_TYPE STREQUAL "Debug")
+        message(FATAL_ERROR "Code coverage results with an optimised (non-Debug) build may be misleading! Add -DCMAKE_BUILD_TYPE=Debug")
+    endif()
+    
+    message("Setting coverage compiler flags")
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -g -O0 -fprofile-arcs -ftest-coverage")
+endif()
+
 if (CMAKE_COMPILER_IS_GNUCC)
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall")
 
@@ -887,6 +904,16 @@ if (NOT EVENT__DISABLE_TESTS)
         add_dependencies(verify regress)
     endif()
 
+    if (EVENT__COVERAGE)
+        include(CodeCoverage)
+
+        setup_target_for_coverage(
+            verify_coverage # Coverage target name "make verify_coverage"
+            make            # Test runner.
+            coverage        # Output directory.
+            verify)         # Arguments passed to test runner. "make verify"
+    endif()
+
     enable_testing()
 
     include(CTest)
diff --git a/cmake/CodeCoverage.cmake b/cmake/CodeCoverage.cmake
new file mode 100644
index 00000000..2afefa1d
--- /dev/null
+++ b/cmake/CodeCoverage.cmake
@@ -0,0 +1,162 @@
+#
+# Boost Software License - Version 1.0 - August 17th, 2003
+#
+# Permission is hereby granted, free of charge, to any person or organization
+# obtaining a copy of the software and accompanying documentation covered by
+# this license (the "Software") to use, reproduce, display, distribute,
+# execute, and transmit the Software, and to prepare derivative works of the
+# Software, and to permit third-parties to whom the Software is furnished to
+# do so, all subject to the following:
+# 
+# The copyright notices in the Software and this entire statement, including
+# the above license grant, this restriction and the following disclaimer,
+# must be included in all copies of the Software, in whole or in part, and
+# all derivative works of the Software, unless such copies or derivative
+# works are solely in the form of machine-executable object code generated by
+# a source language processor.
+# 
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+# SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+# FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+# ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+# DEALINGS IN THE SOFTWARE.
+#
+# 2012-01-31, Lars Bilke
+# - Enable Code Coverage
+#
+# 2013-09-17, Joakim Söderberg
+# - Added support for Clang.
+# - Some additional usage instructions.
+#
+# USAGE:
+# 1. Copy this file into your cmake modules path.
+#
+# 2. Add the following line to your CMakeLists.txt:
+#      INCLUDE(CodeCoverage)
+#
+# 3. Set compiler flags to turn off optimization and enable coverage: 
+#    SET(CMAKE_CXX_FLAGS "-g -O0 -fprofile-arcs -ftest-coverage")
+#	 SET(CMAKE_C_FLAGS "-g -O0 -fprofile-arcs -ftest-coverage")
+#  
+# 3. Use the function SETUP_TARGET_FOR_COVERAGE to create a custom make target
+#    which runs your test executable and produces a lcov code coverage report:
+#    Example:
+#	 SETUP_TARGET_FOR_COVERAGE(
+#				my_coverage_target  # Name for custom target.
+#				test_driver         # Name of the test driver executable that runs the tests.
+#									# NOTE! This should always have a ZERO as exit code
+#									# otherwise the coverage generation will not complete.
+#				coverage            # Name of output directory.
+#				)
+#
+# 4. Build a Debug build:
+#	 cmake -DCMAKE_BUILD_TYPE=Debug ..
+#	 make
+#	 make my_coverage_target
+#
+#
+
+# Check prereqs
+FIND_PROGRAM( GCOV_PATH gcov )
+FIND_PROGRAM( LCOV_PATH lcov )
+FIND_PROGRAM( GENHTML_PATH genhtml )
+FIND_PROGRAM( GCOVR_PATH gcovr PATHS ${CMAKE_SOURCE_DIR}/tests)
+
+IF(NOT GCOV_PATH)
+	MESSAGE(FATAL_ERROR "gcov not found! Aborting...")
+ENDIF() # NOT GCOV_PATH
+
+IF(NOT CMAKE_COMPILER_IS_GNUCXX)
+	# Clang version 3.0.0 and greater now supports gcov as well.
+	MESSAGE(WARNING "Compiler is not GNU gcc! Clang Version 3.0.0 and greater supports gcov as well, but older versions don't.")
+	
+	IF(NOT "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")
+		MESSAGE(FATAL_ERROR "Compiler is not GNU gcc! Aborting...")
+	ENDIF()
+ENDIF() # NOT CMAKE_COMPILER_IS_GNUCXX
+
+IF ( NOT CMAKE_BUILD_TYPE STREQUAL "Debug" )
+  MESSAGE( WARNING "Code coverage results with an optimized (non-Debug) build may be misleading" )
+ENDIF() # NOT CMAKE_BUILD_TYPE STREQUAL "Debug"
+
+
+# Param _targetname     The name of new the custom make target
+# Param _testrunner     The name of the target which runs the tests.
+#						MUST return ZERO always, even on errors. 
+#						If not, no coverage report will be created!
+# Param _outputname     lcov output is generated as _outputname.info
+#                       HTML report is generated in _outputname/index.html
+# Optional fourth parameter is passed as arguments to _testrunner
+#   Pass them in list form, e.g.: "-j;2" for -j 2
+FUNCTION(SETUP_TARGET_FOR_COVERAGE _targetname _testrunner _outputname)
+
+	IF(NOT LCOV_PATH)
+		MESSAGE(FATAL_ERROR "lcov not found! Aborting...")
+	ENDIF() # NOT LCOV_PATH
+
+	IF(NOT GENHTML_PATH)
+		MESSAGE(FATAL_ERROR "genhtml not found! Aborting...")
+	ENDIF() # NOT GENHTML_PATH
+
+	# Setup target
+	ADD_CUSTOM_TARGET(${_targetname}
+		
+		# Cleanup lcov
+		${LCOV_PATH} --directory . --zerocounters
+		
+		# Run tests
+		COMMAND ${_testrunner} ${ARGV3}
+		
+		# Capturing lcov counters and generating report
+		COMMAND ${LCOV_PATH} --directory . --capture --output-file ${_outputname}.info
+		COMMAND ${LCOV_PATH} --remove ${_outputname}.info 'tests/*' '/usr/*' --output-file ${_outputname}.info.cleaned
+		COMMAND ${GENHTML_PATH} -o ${_outputname} ${_outputname}.info.cleaned
+		COMMAND ${CMAKE_COMMAND} -E remove ${_outputname}.info ${_outputname}.info.cleaned
+		
+		WORKING_DIRECTORY ${CMAKE_BINARY_DIR}
+		COMMENT "Resetting code coverage counters to zero.\nProcessing code coverage counters and generating report."
+	)
+	
+	# Show info where to find the report
+	ADD_CUSTOM_COMMAND(TARGET ${_targetname} POST_BUILD
+		COMMAND ;
+		COMMENT "Open ./${_outputname}/index.html in your browser to view the coverage report."
+	)
+
+ENDFUNCTION() # SETUP_TARGET_FOR_COVERAGE
+
+# Param _targetname     The name of new the custom make target
+# Param _testrunner     The name of the target which runs the tests
+# Param _outputname     cobertura output is generated as _outputname.xml
+# Optional fourth parameter is passed as arguments to _testrunner
+#   Pass them in list form, e.g.: "-j;2" for -j 2
+FUNCTION(SETUP_TARGET_FOR_COVERAGE_COBERTURA _targetname _testrunner _outputname)
+
+	IF(NOT PYTHON_EXECUTABLE)
+		MESSAGE(FATAL_ERROR "Python not found! Aborting...")
+	ENDIF() # NOT PYTHON_EXECUTABLE
+
+	IF(NOT GCOVR_PATH)
+		MESSAGE(FATAL_ERROR "gcovr not found! Aborting...")
+	ENDIF() # NOT GCOVR_PATH
+
+	ADD_CUSTOM_TARGET(${_targetname}
+
+		# Run tests
+		${_testrunner} ${ARGV3}
+
+		# Running gcovr
+		COMMAND ${GCOVR_PATH} -x -r ${CMAKE_SOURCE_DIR} -e '${CMAKE_SOURCE_DIR}/tests/'  -o ${_outputname}.xml
+		WORKING_DIRECTORY ${CMAKE_BINARY_DIR}
+		COMMENT "Running gcovr to produce Cobertura code coverage report."
+	)
+
+	# Show info where to find the report
+	ADD_CUSTOM_COMMAND(TARGET ${_targetname} POST_BUILD
+		COMMAND ;
+		COMMENT "Cobertura code coverage report saved in ${_outputname}.xml."
+	)
+
+ENDFUNCTION() # SETUP_TARGET_FOR_COVERAGE_COBERTURA