Add ASSERT_CONTENTS_EQUAL test macro in testing.cmake

Checks if the contents of a file matches the given input

Author: codeinred

cmake/testing.cmake

@@ -79,3 +79,16 @@ function(ASSERT_NOT_EXISTS file)
     message(FATAL_ERROR "assertion failed: file ${file} exists")
   endif()
 endfunction()
+
+function(ASSERT_CONTENTS_EQUAL file content)
+  if(EXISTS ${file})
+    file(READ ${file} file_content)
+    if(content STREQUAL file_content)
+      message(STATUS "test passed: '${file}' exists and contains '${content}'")
+    else()
+      message(FATAL_ERROR "assertion failed: file '${file}' does not contain expected content.")
+    endif()
+  else()
+    message(FATAL_ERROR "assertion failed: file '${file} does not exist")
+  endif()
+endfunction()