Add unit tests + fix

Author: Vasileios Karakasis

reframe/core/warnings.py

@@ -17,7 +17,7 @@ def _format_warning(message, category, filename, lineno, line=None):
     import reframe.utility.color as color
 
     if category != ReframeDeprecationWarning:
-        return _format_warning_orig
+        return _format_warning_orig(message, category, filename, lineno, line)
 
     if line is None:
         # Read in the line from the file

unittests/test_warnings.py

@@ -0,0 +1,51 @@
+import pytest
+import warnings
+
+import reframe.core.runtime as rt
+import reframe.core.warnings as warn
+import reframe.utility.color as color
+import unittests.fixtures as fixtures
+
+
+@pytest.fixture(params=['colors', 'nocolors'])
+def with_colors(request):
+    with rt.temp_runtime(fixtures.BUILTIN_CONFIG_FILE, 'generic',
+                         {'general/colorize': request.param == 'colors'}):
+        yield request.param == 'colors'
+
+
+def test_deprecation_warning():
+    with pytest.warns(warn.ReframeDeprecationWarning):
+        warn.user_deprecation_warning('deprecated')
+
+
+def test_deprecation_warning_formatting(with_colors):
+    message = warnings.formatwarning(
+        'deprecated', warn.ReframeDeprecationWarning, 'file', 10, 'a = 1'
+    )
+    expected = 'file:10: WARNING: deprecated\na = 1\n'
+    if with_colors:
+        expected = color.colorize(expected, color.YELLOW)
+
+    assert message == expected
+
+
+def test_deprecation_warning_formatting_noline(tmp_path, with_colors):
+    srcfile = tmp_path / 'file'
+    srcfile.touch()
+
+    message = warnings.formatwarning(
+        'deprecated', warn.ReframeDeprecationWarning, srcfile, 10
+    )
+    expected = f'{srcfile}:10: WARNING: deprecated\n<no line information>\n'
+    if with_colors:
+        expected = color.colorize(expected, color.YELLOW)
+
+    assert message == expected
+
+
+def test_random_warning_formatting():
+    message = warnings.formatwarning(
+        'deprecated', UserWarning, 'file', 10, 'a = 1'
+    )
+    assert message == f'file:10: UserWarning: deprecated\n  a = 1\n'