Update compare function to reduce duplicated code

Author: davidrudlstorfer

tests/conftest.py

@@ -271,29 +271,44 @@ def _compare(
         Returns:
             bool: true if comparison is successful, false otherwise
         """
-        # Compare two strings
-        if type(reference) is str and type(result) is str:
+
+        # Compare two universal files
+        if isinstance(reference, Path) and isinstance(result, Path):
+            if reference.suffix != result.suffix:
+                raise RuntimeError(
+                    "Reference and result file must be of same file type!"
+                )
+            elif reference.suffix in [".vtk", ".vtu"]:
+                return compare_vtk_files(reference, result, rtol, atol)
+            else:
+                raise NotImplementedError(
+                    f"Comparison is not yet implemented for {reference.suffix} files."
+                )
+        # Compare two strings (no path is available for reference file => no error handling)
+        elif type(reference) is str and type(result) is str:
             return compare_strings(reference, result, rtol, atol, **kwargs)
 
-        # Compare a file with a string
-        elif isinstance(reference, Path) and type(result) is str:
+        # Compare a file with a string/InputFile
+        elif (
+            isinstance(reference, Path)
+            and type(result) is str
+            or isinstance(reference, Path)
+            and isinstance(result, InputFile)
+        ):
+            # retrieve strings
             reference_string = get_string(reference)
 
-            try:
-                return compare_strings(reference_string, result, rtol, atol, **kwargs)
-            except AssertionError as error:
-                return handle_unequal_strings(
-                    error, tmp_path, current_test_name, result, reference
+            if isinstance(result, str):
+                result_string = result
+            elif isinstance(result, InputFile):
+                result_string = result.get_string(
+                    check_nox=input_file_kwargs["input_file_string_check_nox"],
+                    header=input_file_kwargs["input_file_string_check_header"],
                 )
+            else:
+                raise TypeError("Result must be either string or InputFile.")
 
-        # Compare a file with an InputFile
-        elif isinstance(reference, Path) and isinstance(result, InputFile):
-            reference_string = get_string(reference)
-            result_string = result.get_string(
-                check_nox=input_file_kwargs["input_file_string_check_nox"],
-                header=input_file_kwargs["input_file_string_check_header"],
-            )
-
+            # compare strings and handle errors
             try:
                 return compare_strings(
                     reference_string, result_string, rtol, atol, **kwargs
@@ -302,21 +317,10 @@ def _compare(
                 return handle_unequal_strings(
                     error, tmp_path, current_test_name, result_string, reference
                 )
-
-        # Compare two universal files
-        elif isinstance(reference, Path) and isinstance(result, Path):
-            if reference.suffix != result.suffix:
-                raise RuntimeError(
-                    "Reference and result file must be of same file type!"
-                )
-            elif reference.suffix in [".vtk", ".vtu"]:
-                return compare_vtk_files(reference, result, rtol, atol)
-            else:
-                raise NotImplementedError(
-                    f"Comparison is not yet implemented for {reference.suffix} files."
-                )
         else:
-            raise TypeError("Reference and result must be either string or Path.")
+            raise TypeError(
+                "Reference and result must either be string/InputFile or Path!"
+            )
 
     return _compare