Also add auto-updatable output-based tests to examplefiles (#1689)

Co-authored-by: Georg Brandl <georg@python.org>

1 files changed, 108 insertions, 0 deletions

diff --git a/tests/conftest.py b/tests/conftest.py
index def1b770..7ff5ff18 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -1,5 +1,113 @@
+"""
+    Generated lexer tests
+    ~~~~~~~~~~~~~~~~~~~~~
+
+    Checks that lexers output the expected tokens for each sample
+    under lexers/*/test_*.txt.
+
+    After making a change, rather than updating the samples manually,
+    run `pytest --update-goldens tests/lexers tests/examplefiles`.
+
+    To add a new sample, create a new file matching this pattern.
+    The directory must match the alias of the lexer to be used.
+    Populate only the input, then just `--update-goldens`.
+
+    :copyright: Copyright 2021 by the Pygments team, see AUTHORS.
+    :license: BSD, see LICENSE for details.
+"""
+from pathlib import Path
+
 import pytest
 
+import pygments.lexers
+
 
 def pytest_addoption(parser):
     parser.addoption('--update-goldens', action='store_true', help='reset golden master benchmarks')
+
+
+class LexerTestItem(pytest.Item):
+    def __init__(self, name, parent):
+        super().__init__(name, parent)
+        self.lexer = Path(str(self.fspath)).parent.name
+        self.actual = None
+
+    @classmethod
+    def _prettyprint_tokens(cls, tokens):
+        for tok, val in tokens:
+            yield '{!r:<13} {}'.format(val, str(tok)[6:])
+            if val.endswith('\n'):
+                yield ''
+
+    def runtest(self):
+        lexer = pygments.lexers.get_lexer_by_name(self.lexer)
+        tokens = lexer.get_tokens(self.input)
+        self.actual = '\n'.join(self._prettyprint_tokens(tokens)).rstrip('\n') + '\n'
+        if not self.config.getoption('--update-goldens'):
+            assert self.actual == self.expected
+
+    def _test_file_rel_path(self):
+        return Path(str(self.fspath)).relative_to(Path(__file__).parent.parent)
+
+    def repr_failure(self, excinfo):
+        if isinstance(excinfo.value, AssertionError):
+            rel_path = self._test_file_rel_path()
+            message = (
+                'The tokens produced by the "{}" lexer differ from the '
+                'expected ones in the file "{}".\n'
+                'Run `pytest {} --update-goldens` to update it.'
+            ).format(self.lexer, rel_path, Path(*rel_path.parts[:2]))
+            diff = str(excinfo.value).split('\n', 1)[-1]
+            return message + '\n\n' + diff
+
+    def reportinfo(self):
+        return self.fspath, None, str(self._test_file_rel_path())
+
+    def maybe_overwrite(self):
+        if self.actual is not None and self.config.getoption('--update-goldens'):
+            self.overwrite()
+
+
+class LexerSeparateTestItem(LexerTestItem):
+    def __init__(self, name, parent):
+        super().__init__(name, parent)
+
+        self.input = self.fspath.read_binary()
+        output_path = self.fspath + '.output'
+        if output_path.check():
+            self.expected = output_path.read_text(encoding='utf-8')
+        else:
+            self.expected = ''
+
+    def overwrite(self):
+        output_path = self.fspath + '.output'
+        output_path.write_text(self.actual, encoding='utf-8')
+
+
+class LexerInlineTestItem(LexerTestItem):
+    def __init__(self, name, parent):
+        super().__init__(name, parent)
+
+        content = self.fspath.read_text('utf-8')
+        content, _, self.expected = content.partition('\n---tokens---\n')
+        if content.startswith('---input---\n'):
+            content = '\n' + content
+        self.comment, _, self.input = content.rpartition('\n---input---\n')
+        if not self.input.endswith('\n'):
+            self.input += '\n'
+        self.comment = self.comment.strip()
+
+    def overwrite(self):
+        with self.fspath.open('w', encoding='utf-8') as f:
+            f.write(self.comment)
+            if self.comment:
+                f.write('\n\n')
+            f.write('---input---\n')
+            f.write(self.input)
+            f.write('\n---tokens---\n')
+            f.write(self.actual)
+
+
+def pytest_runtest_teardown(item, nextitem):
+    if isinstance(item, LexerTestItem):
+        item.maybe_overwrite()