def test_appendable_raises_valuerror(tmpdir):
"""_is_appendable() raises ValueError when file is only 'a' mode."""
test_file = str(tmpdir.join("test.avro"))
with open(test_file, "a") as new_file:
new_file.write('this phrase forwards cursor position beyond zero')
with pytest.raises(ValueError, match=r"you must use the 'a\+' mode"):
_is_appendable(new_file)
def test_appendable_true_nonzero(tmpdir):
"""_is_appendable() returns True when file_like.tell() is non-zero."""
test_file = str(tmpdir.join("test.avro"))
with open(test_file, "a+b") as new_file:
new_file.write(b'this phrase forwards cursor position beyond zero')
assert _is_appendable(new_file)
def test_appendable_false_stdout(capfd):
"""_is_appendable() returns False when file_like is sys.stdout.buffer."""
# normally, pytest performs "Capturing of stderr/stdout", which is pretty
# great, but it impacts this "integration test": we'd like to use our true
# stdout, whether it is a terminal or pipe, to invoke the true behavior of
# _is_appendable() when used with 'sys.stdout.buffer'.
with capfd.disabled():
assert not _is_appendable(sys.stdout.buffer)
def test_appendable_false_zero():
"""_is_appendable() returns True when file_like.tell() returns 0."""
class MockFileLike:
def seekable(self):
return True
def tell(self):
# mock a 0 position
return 0
assert not _is_appendable(MockFileLike())
def test_appendable_false_unseekable_stream():
"""File streams that cannot seek return False."""
class MockStreamLike:
# This mock file-like object simply returns False for 'seekable', and,
# if 'tell' were called, rasies OSError. This mimicks a streaming
# buffer like sys.stdout.buffer without actually using it.
def seekable(self):
return False
def tell(self):
# mock what a write-only stream would do
raise OSError(29, "Illegal seek")
assert not _is_appendable(MockStreamLike())