Clean json_tools tests

Author: Rémi Lapeyre

Lib/json/tool.py

@@ -39,7 +39,7 @@ def main():
     try:
         outfile = sys.stdout if options.outfile == '-' else open(options.outfile, 'w')
     except IOError as e:
-        parser.error("can't open '{}': {}".format(options.outfile, str(e)))
+        parser.error(f"can't open '{options.outfile}': {str(e)}")
     with outfile:
         json.dump(obj, outfile, sort_keys=sort_keys, indent=4)
         outfile.write('\n')

Lib/test/test_json/test_tool.py

@@ -80,7 +80,6 @@ def _create_infile(self):
     def test_infile_stdout(self):
         infile = self._create_infile()
         rc, out, err = assert_python_ok('-m', 'json.tool', infile)
-        self.assertEqual(rc, 0)
         self.assertEqual(out.splitlines(), self.expect.encode().splitlines())
         self.assertEqual(err, b'')
 
@@ -91,14 +90,12 @@ def test_infile_outfile(self):
         self.addCleanup(os.remove, outfile)
         with open(outfile, "r") as fp:
             self.assertEqual(fp.read(), self.expect)
-        self.assertEqual(rc, 0)
         self.assertEqual(out, b'')
         self.assertEqual(err, b'')
 
     def test_infile_same_outfile(self):
         infile = self._create_infile()
         rc, out, err = assert_python_ok('-m', 'json.tool', infile, infile)
-        self.assertEqual(rc, 0)
         self.assertEqual(out, b'')
         self.assertEqual(err, b'')
 
@@ -107,40 +104,23 @@ def test_unavailable_outfile(self):
         rc, out, err = assert_python_failure('-m', 'json.tool', infile, '/bla/outfile')
         self.assertEqual(rc, 2)
         self.assertEqual(out, b'')
-        err = err.decode().splitlines()
-        self.assertEqual(err[0], 'usage: python -m json.tool [-h] [--sort-keys] [infile] [outfile]')
-        self.assertEqual(err[1], "python -m json.tool: error: can't open '/bla/outfile': [Errno 2] No such file or directory: '/bla/outfile'")
+        self.assertIn(b"error: can't open '/bla/outfile': [Errno 2]", err)
 
     def test_help_flag(self):
         rc, out, err = assert_python_ok('-m', 'json.tool', '-h')
-        self.assertEqual(rc, 0)
         self.assertTrue(out.startswith(b'usage: '))
         self.assertEqual(err, b'')
 
     def test_sort_keys_flag(self):
         infile = self._create_infile()
         rc, out, err = assert_python_ok('-m', 'json.tool', '--sort-keys', infile)
-        self.assertEqual(rc, 0)
         self.assertEqual(out.splitlines(),
                          self.expect_without_sort_keys.encode().splitlines())
         self.assertEqual(err, b'')
 
     def test_no_fd_leak_infile_outfile(self):
-        closed = []
-        opened = []
-        io_open = io.open
-
-        def open(*args, **kwargs):
-            fd = io_open(*args, **kwargs)
-            opened.append(fd)
-            fd_close = fd.close
-            def close(self):
-                closed.append(self)
-                fd_close()
-            fd.close = types.MethodType(close, fd)
-            return fd
-
         infile = self._create_infile()
+        closed, opened, open = mock_open()
         with mock.patch('builtins.open', side_effect=open):
             with mock.patch.object(sys, 'argv', ['tool.py', infile, infile + '.out']):
                 import json.tool
@@ -151,28 +131,31 @@ def close(self):
         self.assertEqual(len(opened), len(closed))
 
     def test_no_fd_leak_same_infile_outfile(self):
-        closed = []
-        opened = []
-        io_open = io.open
-
-        def open(*args, **kwargs):
-            fd = io_open(*args, **kwargs)
-            opened.append(fd)
-            fd_close = fd.close
-            def close(self):
-                closed.append(self)
-                fd_close()
-            fd.close = types.MethodType(close, fd)
-            return fd
-
         infile = self._create_infile()
+        closed, opened, open = mock_open()
         with mock.patch('builtins.open', side_effect=open):
             with mock.patch.object(sys, 'argv', ['tool.py', infile, infile]):
                 try:
                     import json.tool
                     json.tool.main()
-                except SystemExit:  # We expect SystemExit to happen on c9d43c
+                except SystemExit:
                     pass
 
         self.assertEqual(opened, closed)
         self.assertEqual(len(opened), len(closed))
+
+def mock_open():
+    closed = []
+    opened = []
+    io_open = io.open
+
+    def _open(*args, **kwargs):
+        fd = io_open(*args, **kwargs)
+        opened.append(fd)
+        fd_close = fd.close
+        def close(self):
+            closed.append(self)
+            fd_close()
+        fd.close = types.MethodType(close, fd)
+        return fd
+    return closed, opened, _open