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"""Tests for the pngchunks tool."""
from tests import base
class TestPngchunks(base.PngtoolsTestCase):
"""Test pngchunks chunk listing."""
def test_lists_ihdr(self):
"""Output contains an IHDR chunk."""
result = self.run_tool(
'pngchunks', [self.sample_path('input.png')]
)
self.assertEqual(0, result.returncode)
self.assertIn('[IHDR]', result.stdout)
def test_lists_iend(self):
"""Output contains an IEND chunk."""
result = self.run_tool(
'pngchunks', [self.sample_path('input.png')]
)
self.assertIn('[IEND]', result.stdout)
def test_lists_idat(self):
"""Output contains at least one IDAT chunk."""
result = self.run_tool(
'pngchunks', [self.sample_path('input.png')]
)
self.assertIn('[IDAT]', result.stdout)
def test_ihdr_dimensions(self):
"""IHDR chunk shows correct width and height."""
result = self.run_tool(
'pngchunks', [self.sample_path('input.png')]
)
self.assertIn('IHDR Width: 256', result.stdout)
self.assertIn('IHDR Height: 256', result.stdout)
def test_ihdr_bitdepth(self):
"""IHDR chunk shows correct bitdepth."""
result = self.run_tool(
'pngchunks', [self.sample_path('input.png')]
)
self.assertIn('IHDR Bitdepth: 8', result.stdout)
def test_chunk_properties_critical(self):
"""IHDR is identified as critical and public."""
result = self.run_tool(
'pngchunks', [self.sample_path('input.png')]
)
# The line after IHDR should describe its properties
self.assertIn('Critical, public', result.stdout)
def test_ancillary_chunks(self):
"""input.png has ancillary chunks like bKGD or pHYs."""
result = self.run_tool(
'pngchunks', [self.sample_path('input.png')]
)
# input.png is known to have bKGD, pHYs, tIME
has_ancillary = (
'[bKGD]' in result.stdout
or '[pHYs]' in result.stdout
or '[tIME]' in result.stdout
)
self.assertTrue(
has_ancillary,
'Expected ancillary chunks in output'
)
def test_compression_algorithm(self):
"""IHDR compression algorithm is identified as Deflate."""
result = self.run_tool(
'pngchunks', [self.sample_path('input.png')]
)
self.assertIn(
'Compression algorithm is Deflate', result.stdout
)
def test_chunk_crc(self):
"""Each chunk has a CRC value displayed."""
result = self.run_tool(
'pngchunks', [self.sample_path('input.png')]
)
self.assertIn('Chunk CRC:', result.stdout)
def test_iend_no_data(self):
"""IEND chunk reports containing no data."""
result = self.run_tool(
'pngchunks', [self.sample_path('input.png')]
)
self.assertIn('IEND contains no data', result.stdout)
class TestPngchunksErrors(base.PngtoolsTestCase):
"""Test pngchunks error handling."""
def test_no_arguments(self):
"""No arguments prints usage and exits 1."""
result = self.run_tool('pngchunks')
self.assertEqual(1, result.returncode)
self.assertIn('Usage:', result.stderr)
def test_missing_file(self):
"""Missing file prints error and exits 1."""
result = self.run_tool(
'pngchunks', ['/nonexistent/file.png']
)
self.assertEqual(1, result.returncode)
self.assertIn('Could not open', result.stderr)
def test_invalid_file(self):
"""Non-PNG file prints error and exits 1."""
result = self.run_tool(
'pngchunks', [self.invalid_file]
)
self.assertEqual(1, result.returncode)
self.assertIn('not a PNG file', result.stderr)
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