feat: add support to format file recency assertion errors

cmake/Assertion.cmake

@@ -232,6 +232,9 @@ function(assert)
       if(ARGV1 STREQUAL "IN_LIST")
         fail("expected string" ARGV0 "to exist in" ARGV2)
         return()
+      elseif(ARGV1 STREQUAL "IS_NEWER_THAN")
+        fail("expected file" ARGV0 "to be newer than" ARGV2)
+        return()
       elseif(ARGV1 STREQUAL "MATCHES")
         fail("expected string" ARGV0 "to match" ARGV2)
         return()
@@ -245,6 +248,9 @@ function(assert)
       if(ARGV2 STREQUAL "IN_LIST")
         fail("expected string" ARGV1 "not to exist in" ARGV3)
         return()
+      elseif(ARGV2 STREQUAL "IS_NEWER_THAN")
+        fail("expected file" ARGV1 "not to be newer than" ARGV3)
+        return()
       elseif(ARGV2 STREQUAL "MATCHES")
         fail("expected string" ARGV1 "not to match" ARGV3)
         return()

test/assert.cmake

@@ -295,6 +295,26 @@ section("executable path condition assertions")
   endsection()
 endsection()
 
+section("file recency condition assertions")
+  file(WRITE old_file "something")
+  file(WRITE new_file "something")
+
+  section("it should assert file recency conditions")
+    assert(new_file IS_NEWER_THAN old_file)
+    assert(NOT old_file IS_NEWER_THAN new_file)
+  endsection()
+
+  section("it should fail to assert file recency conditions")
+    assert_fatal_error(
+      CALL assert old_file IS_NEWER_THAN new_file
+      MESSAGE "expected file:\n  old_file\nto be newer than:\n  new_file")
+
+    assert_fatal_error(
+      CALL assert NOT new_file IS_NEWER_THAN old_file
+      MESSAGE "expected file:\n  new_file\nnot to be newer than:\n  old_file")
+  endsection()
+endsection()
+
 section("directory path condition assertions")
   file(MAKE_DIRECTORY some_directory)
   file(TOUCH some_file)