c.library.cli: extract check_library printing

- extract printing/formatting logic from
  calibre.library.cli.command_check_library

- add tests asserting current behaviour

src/calibre/library/cli.py

@@ -1362,7 +1362,19 @@ def command_check_library(args, dbpath):
     else:
         exts = [f.strip() for f in opts.exts.split(',') if f.strip()]
 
-    def print_one(checker, check):
+
+    if not LibraryDatabase.exists_at(dbpath):
+        prints('No library found at', dbpath, file=sys.stderr)
+        raise SystemExit(1)
+
+    db = LibraryDatabase(dbpath)
+    checker = CheckLibrary(dbpath, db)
+    checker.scan_library(names, exts)
+    for check in checks:
+        _print_check_library_results(checker, check)
+
+
+def _print_check_library_results(checker, check, opts):
     attr = check[0]
     list = getattr(checker, attr, None)
     if list is None:
@@ -1375,16 +1387,6 @@ def command_check_library(args, dbpath):
         for i in list:
             print '    %-40.40s - %-40.40s'%(i[0], i[1])
 
-    if not LibraryDatabase.exists_at(dbpath):
-        prints('No library found at', dbpath, file=sys.stderr)
-        raise SystemExit(1)
-
-    db = LibraryDatabase(dbpath)
-    checker = CheckLibrary(dbpath, db)
-    checker.scan_library(names, exts)
-    for check in checks:
-        print_one(checker, check)
-
 
 def restore_database_option_parser():
     parser = get_parser(_(

src/calibre/library/test_cli.py

@@ -0,0 +1,101 @@
+#!/usr/bin/env python2
+# vim:fileencoding=UTF-8:ts=4:sw=4:sta:et:sts=4:ai
+from __future__ import (unicode_literals, division, absolute_import,
+                        print_function)
+
+__license__ = 'GPL v3'
+__docformat__ = 'restructuredtext en'
+
+'''
+Test the CLI of the calibre database management tool
+'''
+import csv, sys
+import unittest
+from StringIO import StringIO
+
+from mock import Mock, patch
+
+from calibre.library.check_library import CheckLibrary
+from calibre.library.cli import _print_check_library_results
+
+
+class PrintCheckLibraryResultsTest(unittest.TestCase):
+    """
+    Asserts the format of the output to the CLI to avoid regressions
+    """
+    check_machine_name = 'dummy_check'
+    check_human_name = 'Dummy Check'
+    check = (check_machine_name, check_human_name, True, False)
+
+    @patch('sys.stdout', new_callable=StringIO)
+    def test_prints_nothing_if_no_errors(self, mock_stdout):
+        checker = Mock(name='checker', spec=CheckLibrary)
+        setattr(checker, self.check_machine_name, None)
+        opts = Mock()
+
+        opts.csv = False
+        _print_check_library_results(checker, self.check, opts)
+        self.assertEqual(mock_stdout.getvalue(), '')
+
+        opts.csv = True
+        _print_check_library_results(checker, self.check, opts)
+        self.assertEqual(mock_stdout.getvalue(), '')
+
+    @patch('sys.stdout', new_callable=StringIO)
+    def test_human_readable_output(self, mock_stdout):
+        """
+        Basic check of the human-readable output.
+
+        Does not test: the full line format, truncation
+        """
+        checker = Mock(name='checker', speck=CheckLibrary)
+        data = [['first', 'second']]
+        opts = Mock()
+        opts.csv = False
+        setattr(checker, self.check_machine_name, data)
+        _print_check_library_results(checker, self.check, opts)
+
+        result = mock_stdout.getvalue().split('\n')
+        self.assertEqual(len(result), len(data)+2)
+        self.assertEqual(result[0], self.check_human_name)
+
+        result_first = result[1].split('-')[0].strip()
+        result_second = result[1].split('-')[1].strip()
+
+        self.assertEqual(result_first, 'first')
+        self.assertEqual(result_second, 'second')
+
+        self.assertEqual(result[-1], '')
+
+    @patch('sys.stdout', new_callable=StringIO)
+    def test_basic_csv_output(self, mock_stdout):
+        """
+        Test simple csv output
+        """
+        checker = Mock(name='checker', speck=CheckLibrary)
+        data = [['first', 'second']]
+        opts = Mock()
+        opts.csv = True
+        setattr(checker, self.check_machine_name, data)
+        _print_check_library_results(checker, self.check, opts)
+
+        result = mock_stdout.getvalue().split('\n')
+        parsed_result = [l for l in csv.reader(result) if l]
+        self.assertEqual(parsed_result, [[self.check_human_name, data[0][0], data[0][1]]])
+
+    @patch('sys.stdout', new_callable=StringIO)
+    def test_escaped_csv_output(self, mock_stdout):
+        """
+        Test more complex csv output
+        """
+        raise unittest.SkipTest('This test fails, as csv output does not currently escape')
+        checker = Mock(name='checker', speck=CheckLibrary)
+        data = [['I, Caesar', 'second']]
+        opts = Mock()
+        opts.csv = True
+        setattr(checker, self.check_machine_name, data)
+        _print_check_library_results(checker, self.check, opts)
+
+        result = mock_stdout.getvalue().split('\n')
+        parsed_result = [l for l in csv.reader(result) if l]
+        self.assertEqual(parsed_result, [[self.check_human_name, data[0][0], data[0][1]]])