def test_dictwriter_append_header_only():
fileobj = StringIO()
writer1 = DictWriter(fileobj, fieldnames=["f1", "f2", "f3"])
writer1.writeheader()
assert fileobj.getvalue() == "f1,f2,f3\r\n"
writer2 = DictWriter.append(fileobj)
writer2.writerow({"f1": 2, "f2": 5, "f3": "xyz"})
assert fileobj.getvalue() == "f1,f2,f3\r\n2,5,xyz\r\n"
def test_dictwriter_append_header_only():
fileobj = StringIO()
writer1 = DictWriter(fileobj, fieldnames=["f1", "f2", "f3"])
writer1.writeheader()
assert fileobj.getvalue() == "f1,f2,f3\r\n"
writer2 = DictWriter.append(fileobj)
writer2.writerow({"f1": 2, "f2": 5, "f3": "xyz"})
assert fileobj.getvalue() == "f1,f2,f3\r\n2,5,xyz\r\n"
def test_dictwriter_append_empty():
fileobj = StringIO()
with pytest.raises(ValueError):
writer = DictWriter.append(fileobj)
def test_dictwriter_append_empty():
fileobj = StringIO()
with pytest.raises(ValueError):
writer = DictWriter.append(fileobj)
