Improve test coverage for command line functions

Author: colinpalmer

mrcfile/validator.py

@@ -17,10 +17,11 @@
                         unicode_literals)
 
 import argparse
+import sys
 
 from . import load_functions
 
-def main():
+def main(args=None):
     """
     Validate a list of MRC files given as command arguments.
     
@@ -32,14 +33,16 @@ def main():
         ``0`` if all command arguments are names of valid MRC files. ``1`` if
         no file names are given or any of the files is not a valid MRC file.
     """
+    if args is None:
+        args = sys.argv[1:]
     parser = argparse.ArgumentParser(
         description="Validate a list of MRC files. Exit status is 0 if all "
                     "input files are valid, or 1 if any input file is "
                     "invalid. Descriptions of the problems with any invalid "
                     "files are written to the standard output."
     )
     parser.add_argument("filename", nargs='*', help="Input MRC file")
-    args = parser.parse_args()
+    args = parser.parse_args(args)
     names = args.filename
     if validate_all(names):
         return 0

tests/test_command_line.py

@@ -16,7 +16,7 @@
 import tempfile
 import unittest
 
-from mrcfile import command_line
+from mrcfile import command_line, validator
 from . import helpers
 
 
@@ -56,7 +56,21 @@ def tearDown(self):
         if os.path.exists(self.test_output):
             shutil.rmtree(self.test_output)
         super(CommandLineTest, self).tearDown()
-    
+
+    def test_print_header_no_args(self):
+        command_line.print_headers([], print_file=self.print_stream)
+        assert len(self.print_stream.getvalue()) == 0
+        assert len(sys.stdout.getvalue()) == 0
+        assert len(sys.stderr.getvalue()) == 0
+
+    def test_print_header_nonexistent_file(self):
+        with self.assertRaisesRegex(IOError, "No such file"):
+            command_line.print_headers(["nonexistent.mrc"],
+                                       print_file=self.print_stream)
+        assert len(self.print_stream.getvalue()) == 0
+        assert len(sys.stdout.getvalue()) == 0
+        assert len(sys.stderr.getvalue()) == 0
+
     def test_print_header(self):
         command_line.print_headers(self.files, print_file=self.print_stream)
         printed = self.print_stream.getvalue()
@@ -67,6 +81,20 @@ def test_print_header(self):
         assert len(sys.stdout.getvalue()) == 0
         assert len(sys.stderr.getvalue()) == 0
 
+    def test_validate_no_args(self):
+        result = validator.main([])
+        assert result == 0
+        assert len(self.print_stream.getvalue()) == 0
+        assert len(sys.stdout.getvalue()) == 0
+        assert len(sys.stderr.getvalue()) == 0
+    
+    def test_validate(self):
+        result = validator.main(self.files)
+        assert result == 1
+        stdout = str(sys.stdout.getvalue())
+        assert "File does not declare MRC format version 20140" in stdout
+        assert len(sys.stderr.getvalue()) == 0
+
 
 if __name__ == '__main__':
     unittest.main()