Merge pull request #22 from RoelAdriaans/feature/add-chapter-9-contro…

…lflow

Add a few more test cases

tests/test_control.py

@@ -1,3 +1,5 @@
+from yaplox.parser import Parser
+from yaplox.scanner import Scanner
 from yaplox.yaplox import Yaplox
 
 
@@ -220,3 +222,99 @@ def test_for_expression_init(self, capsys):
         expected_str_output = "\n".join([str(n) for n in range(6)]) + "\n"
 
         assert captured.out == expected_str_output
+
+    def test_for_parser(self, mocker):
+        """ Test that we parse the for loop correctly """
+
+        source = "for(var a = 0; ; a = a + 1) {}"
+
+        on_scanner_error_mock = mocker.MagicMock()
+        on_parser_error_mock = mocker.MagicMock()
+
+        scanner = Scanner(source, on_error=on_scanner_error_mock)
+        tokens = scanner.scan_tokens()
+        parser = Parser(tokens, on_token_error=on_parser_error_mock)
+        statements = parser.parse()
+
+        assert statements
+        # Because the condition is missing, it must alway be true:
+        assert statements[0].statements[1].condition.value is True
+
+        assert not on_scanner_error_mock.called
+        assert not on_parser_error_mock.called
+
+    def test_for_invalid_for_loop_parser(self, mocker):
+        """ Test that we parse the for loop correctly """
+
+        source = "for (var a = 0; a <= 5; a = a + 1) {}"
+        left_missing = source.replace("(", "")
+        right_missing = source.replace(")", "")
+
+        on_scanner_error_mock = mocker.MagicMock()
+        on_parser_error_mock = mocker.MagicMock()
+
+        scanner = Scanner(source, on_error=on_scanner_error_mock)
+        tokens = scanner.scan_tokens()
+        parser = Parser(tokens, on_token_error=on_parser_error_mock)
+        statements = parser.parse()
+
+        assert statements
+        assert not on_scanner_error_mock.called
+        assert not on_parser_error_mock.called
+
+        # Test a invalid statement, missing (
+        on_scanner_error_mock = mocker.MagicMock()
+        on_parser_error_mock = mocker.MagicMock()
+        scanner = Scanner(left_missing, on_error=on_scanner_error_mock)
+        tokens = scanner.scan_tokens()
+        parser = Parser(tokens, on_token_error=on_parser_error_mock)
+        parser.parse()
+
+        assert not on_scanner_error_mock.called
+        assert on_parser_error_mock.called
+        assert "Expect '(' after 'for'" in str(on_parser_error_mock.call_args_list[0])
+
+        # Test a invalid statement, missing )
+        on_scanner_error_mock = mocker.MagicMock()
+        on_parser_error_mock = mocker.MagicMock()
+        scanner = Scanner(right_missing, on_error=on_scanner_error_mock)
+        tokens = scanner.scan_tokens()
+        parser = Parser(tokens, on_token_error=on_parser_error_mock)
+        parser.parse()
+
+        assert not on_scanner_error_mock.called
+        assert on_parser_error_mock.called
+        assert "Expect ')' after for clauses" in str(
+            on_parser_error_mock.call_args_list[0]
+        )
+
+    def test_for_missing_increment(self, capsys):
+        """ Missing increment should still work """
+        source = [
+            "for(var a = 0;  a <= 5;) {",
+            "    print a;",
+            "    a = a + 1;" "}",
+        ]
+        source = "\n".join(source)
+        yaplox = Yaplox()
+        yaplox.run(source)
+
+        assert not yaplox.had_error
+        assert not yaplox.had_runtime_error
+
+        captured = capsys.readouterr()
+        expected_str_output = "\n".join([str(n) for n in range(6)]) + "\n"
+
+        assert captured.out == expected_str_output
+
+        # But the trailing ; must be present
+        source = source.replace("5;)", "5)")
+        yaplox = Yaplox()
+        yaplox.run(source)
+
+        assert yaplox.had_error
+        assert not yaplox.had_runtime_error
+
+        captured = capsys.readouterr()
+
+        assert "Expect ';' after loop condition." in captured.err