#18151, part 2: Silence debug build resource warning for each file opened by

'Find in files' by replacing 'open with implicit close' by 'with open' in
GrepDialog method grep_it. Streamline code with enumerate(), direct file
iteration, and output tweak. Add test for this method, including output format.

Lib/idlelib/idle_test/test_grep.py

@@ -0,0 +1,80 @@
+""" !Changing this line will break Test_findfile.test_found!
+Non-gui unit tests for idlelib.GrepDialog methods.
+dummy_command calls grep_it calls findfiles.
+An exception raised in one method will fail callers.
+Otherwise, tests are mostly independent.
+*** Currently only test grep_it.
+"""
+import unittest
+from test.support import captured_stdout
+from idlelib.idle_test.mock_tk import Var
+from idlelib.GrepDialog import GrepDialog
+import re
+
+class Dummy_searchengine:
+    '''GrepDialog.__init__ calls parent SearchDiabolBase which attaches the
+    passed in SearchEngine instance as attribute 'engine'. Only a few of the
+    many possible self.engine.x attributes are needed here.
+    '''
+    def getpat(self):
+        return self._pat
+
+searchengine = Dummy_searchengine()
+
+class Dummy_grep:
+    # Methods tested
+    #default_command = GrepDialog.default_command
+    grep_it = GrepDialog.grep_it
+    findfiles = GrepDialog.findfiles
+    # Other stuff needed
+    recvar = Var(False)
+    engine = searchengine
+    def close(self):  # gui method
+        pass
+
+grep = Dummy_grep()
+
+class FindfilesTest(unittest.TestCase):
+    # findfiles is really a function, not a method, could be iterator
+    # test that filename return filename
+    # test that idlelib has many .py files
+    # test that recursive flag adds idle_test .py files
+    pass
+
+class Grep_itTest(unittest.TestCase):
+    # Test captured reports with 0 and some hits.
+    # Should test file names, but Windows reports have mixed / and \ separators
+    # from incomplete replacement, so 'later'.
+
+    def report(self, pat):
+        grep.engine._pat = pat
+        with captured_stdout() as s:
+            grep.grep_it(re.compile(pat), __file__)
+        lines = s.getvalue().split('\n')
+        lines.pop()  # remove bogus '' after last \n
+        return lines
+
+    def test_unfound(self):
+        pat = 'xyz*'*7
+        lines = self.report(pat)
+        self.assertEqual(len(lines), 2)
+        self.assertIn(pat, lines[0])
+        self.assertEqual(lines[1], 'No hits.')
+
+    def test_found(self):
+
+        pat = '""" !Changing this line will break Test_findfile.test_found!'
+        lines = self.report(pat)
+        self.assertEqual(len(lines), 5)
+        self.assertIn(pat, lines[0])
+        self.assertIn('py: 1:', lines[1])  # line number 1
+        self.assertIn('2', lines[3])  # hits found 2
+        self.assertTrue(lines[4].startswith('(Hint:'))
+
+class Default_commandTest(unittest.TestCase):
+    # To write this, mode OutputWindow import to top of GrepDialog
+    # so it can be replaced by captured_stdout in class setup/teardown.
+    pass
+
+if __name__ == '__main__':
+    unittest.main(verbosity=2, exit=False)