Fail early if definitions contain non-existent path

If the configuration file explicitly lists paths for CMake
definitions, gersemi should fail early if one of them does not exist.
Otherwise, problems (like typos) with these paths may be detected only
later - especially when using gersemi as pre-commit hook.

Co-Authored-By: Blank Spruce <32396809+BlankSpruce@users.noreply.github.com>

Author: opajonk

gersemi/__main__.py

@@ -224,8 +224,12 @@ def main():
     if len(args.sources) < 1:
         sys.exit(SUCCESS)
 
-    configuration = make_configuration(args)
-    mode = get_mode(args)
+    try:
+        configuration = make_configuration(args)
+        mode = get_mode(args)
+    except Exception as exception:  # pylint: disable=broad-except
+        print_to_stderr(exception)
+        sys.exit(FAIL)
 
     sys.exit(run(mode, configuration, args.sources))
 

gersemi/configuration.py

@@ -233,7 +233,7 @@ def enter_directory(target_directory):
 
 
 def normalize_definitions(definitions):
-    return [Path(d).resolve() for d in definitions]
+    return [Path(d).resolve(True) for d in definitions]
 
 
 def sanitize_list_expansion(list_expansion):

tests/test_executable.py

@@ -1146,3 +1146,31 @@ def assert_that_cache_was_used(inspector):
             gersemi_("--cache", "--check", target, "--definitions", target, cwd=target)
 
         assert_that_cache_was_used(inspector)
+
+
+def test_definition_path_doesnt_exist():
+    with temporary_dir_copy(TESTS / "custom_project") as project:
+        sources = Path(project) / "formatted"
+        definitions = Path(project) / "formatted"
+        common_args = ["--check", sources, "--definitions"]
+
+        assert_success(*common_args, definitions)
+
+        assert_fail(*common_args, Path(project) / "this_path_doesnt_exist")
+
+        assert_success(*common_args, definitions / ".." / "formatted")
+
+        assert_fail(*common_args, definitions / ".." / ".." / "formatted")
+
+        definitions_as_files = [
+            definitions / "back_to_the_future.cmake",
+            definitions / "back_to_the_future_sequels.cmake",
+        ]
+        assert_success(*common_args, *definitions_as_files)
+
+        definitions_as_files_with_path_that_doesnt_exist = [
+            definitions / "back_to_the_future.cmake",
+            definitions / "back_to_the_future_sequels.cmake",
+            definitions / "back_to_the_future_four.cmake",
+        ]
+        assert_fail(*common_args, *definitions_as_files_with_path_that_doesnt_exist)