tests: Exclude lines from coverage

Exclude things like "raise NotImplementedError" and compiler bug
handlers.

.coveragerc

@@ -0,0 +1,6 @@
+[report]
+exclude_lines =
+    pragma: no cover
+    raise AssertionError
+    raise NotImplementedError
+    raise CompilerBugError

blueprintcompiler/errors.py

@@ -121,7 +121,7 @@ def assert_true(truth: bool, message:str=None):
         raise CompilerBugError(message)
 
 
-def report_bug():
+def report_bug(): # pragma: no cover
     """ Report an error and ask people to report it. """
 
     print(traceback.format_exc())

tests/test_samples.py

@@ -46,11 +46,11 @@ class TestSamples(unittest.TestCase):
                 raise MultipleErrors(ast.errors)
 
             actual = ast.generate()
-            if actual.strip() != expected.strip():
+            if actual.strip() != expected.strip(): # pragma: no cover
                 diff = difflib.unified_diff(expected.splitlines(), actual.splitlines())
                 print("\n".join(diff))
                 raise AssertionError()
-        except PrintableError as e:
+        except PrintableError as e: # pragma: no cover
             e.pretty_print(name + ".blp", blueprint)
             raise AssertionError()
 
@@ -79,14 +79,14 @@ class TestSamples(unittest.TestCase):
                 actual = error_str(e)
             elif isinstance(e, MultipleErrors):
                 actual = "\n".join([error_str(error) for error in e.errors])
-            else:
+            else: # pragma: no cover
                 raise AssertionError()
 
-            if actual.strip() != expected.strip():
+            if actual.strip() != expected.strip(): # pragma: no cover
                 diff = difflib.unified_diff(expected.splitlines(), actual.splitlines())
                 print("\n".join(diff))
                 raise AssertionError()
-        else:
+        else: # pragma: no cover
             # Expected a compiler error but there wasn't one
             raise AssertionError()
 
@@ -101,11 +101,11 @@ class TestSamples(unittest.TestCase):
 
             actual = decompiler.decompile(ui_path)
 
-            if actual.strip() != expected.strip():
+            if actual.strip() != expected.strip(): # pragma: no cover
                 diff = difflib.unified_diff(expected.splitlines(), actual.splitlines())
                 print("\n".join(diff))
                 raise AssertionError()
-        except PrintableError as e:
+        except PrintableError as e: # pragma: no cover
             e.pretty_print(name + ".blp", blueprint)
             raise AssertionError()
 

tests/test_tokenizer.py

@@ -32,7 +32,7 @@ class TestTokenizer(unittest.TestCase):
             for token, (type, token_str) in zip(tokens, expect):
                 self.assertEqual(token.type, type)
                 self.assertEqual(str(token), token_str)
-        except PrintableError as e:
+        except PrintableError as e: # pragma: no cover
             e.pretty_print("<test input>", string)
             raise e
 
@@ -71,6 +71,3 @@ class TestTokenizer(unittest.TestCase):
             (TokenType.EOF, ""),
         ])
 
-
-if __name__ == "__main__":
-    unittest.main()