add tests for UsageError

tests/test_cli.py

@@ -2,7 +2,9 @@
 
 import os
 
+from click import UsageError
 from click.testing import CliRunner
+import pytest
 
 from camelot.cli import cli
 from camelot.utils import TemporaryDirectory
@@ -22,6 +24,12 @@ def test_cli_lattice():
         assert result.exit_code == 0
         assert result.output == 'Found 1 tables\n'
 
+        result = runner.invoke(cli, ['--format', 'csv', 'lattice', infile])
+        assert 'Error: Please specify output file path using --output' in result.output
+
+        result = runner.invoke(cli, ['--output', outfile, 'lattice', infile])
+        assert 'Please specify output file format using --format' in result.output
+
 
 def test_cli_stream():
     with TemporaryDirectory() as tempdir:
@@ -31,4 +39,10 @@ def test_cli_stream():
         result = runner.invoke(cli, ['--format', 'csv', '--output', outfile,
                                      'stream', infile])
         assert result.exit_code == 0
-        assert result.output == 'Found 1 tables\n'
+        assert result.output == 'Found 1 tables\n'
+
+        result = runner.invoke(cli, ['--format', 'csv', 'stream', infile])
+        assert 'Error: Please specify output file path using --output' in result.output
+
+        result = runner.invoke(cli, ['--output', outfile, 'stream', infile])
+        assert 'Please specify output file format using --format' in result.output