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"""Base test case for pngtools tests."""
import os
import subprocess
import types
import fixtures
import testtools
# Project root is the parent of the tests/ directory
PROJECT_ROOT = os.path.dirname(os.path.dirname(os.path.abspath(
__file__)))
# Paths to the sample images shipped in the repository
SAMPLE_DIR = PROJECT_ROOT
# Path to generated test images
TESTDATA_DIR = os.path.join(PROJECT_ROOT, 'testdata')
def _ensure_test_images():
"""Generate test images if they don't exist yet."""
marker = os.path.join(TESTDATA_DIR, 'with_text.png')
if not os.path.exists(marker):
script = os.path.join(
PROJECT_ROOT, 'tests', 'generate_test_images.py'
)
subprocess.run(
['python3', script],
check=True,
capture_output=True
)
class PngtoolsTestCase(testtools.TestCase):
"""Base test case with helpers for running pngtools binaries."""
def setUp(self):
super().setUp()
self.tmpdir = self.useFixture(fixtures.TempDir())
# Verify binaries are built
for binary in ['pnginfo', 'pngchunks', 'pngchunkdesc',
'pngcp']:
path = os.path.join(PROJECT_ROOT, binary)
if not os.path.exists(path):
self.skipTest(
f'{binary} not built; run make first'
)
# Ensure generated test images exist
_ensure_test_images()
# Create an invalid (non-PNG) file for error tests
self.invalid_file = os.path.join(
self.tmpdir.path, 'invalid.txt'
)
with open(self.invalid_file, 'w') as f:
f.write('this is not a png file')
def run_tool(self, name, args=None, stdin_data=None):
"""Run a pngtools binary and return the result.
Returns a SimpleNamespace with .stdout, .stderr,
and .returncode.
"""
if args is None:
args = []
binary = os.path.join(PROJECT_ROOT, name)
cmd = [binary] + args
result = subprocess.run(
cmd,
capture_output=True,
text=True,
input=stdin_data,
cwd=PROJECT_ROOT,
timeout=30
)
return types.SimpleNamespace(
stdout=result.stdout,
stderr=result.stderr,
returncode=result.returncode
)
def run_pnginfo(self, filename, flags=None):
"""Convenience wrapper for running pnginfo."""
if flags is None:
flags = []
return self.run_tool('pnginfo', flags + [filename])
def sample_path(self, filename):
"""Return the full path to a sample PNG in the repo."""
return os.path.join(SAMPLE_DIR, filename)
def generated_path(self, filename):
"""Return the full path to a generated test PNG."""
return os.path.join(TESTDATA_DIR, filename)
def tmp_path(self, filename):
"""Return a path in the temp directory for output."""
return os.path.join(self.tmpdir.path, filename)
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