Add download twice test.

tests/command_download.py

@@ -48,3 +48,36 @@ def snippet_call_download_raises(self, expected_exception, url, is_system=False,
     args = get_parser().parse_args(args=args)
     with self.assertRaises(expected_exception):
         download(args)
+
+
+def snippet_call_download_twice(self, url1, url2, files, is_system=False, is_silent=False, type='files'):
+    assert type in 'files' or 'json'
+    if type == 'json':
+        files = get_files_from_json(files)
+
+    with tests.utils.sandbox([]):
+        args = ['download', url1]
+        if is_system:
+            args += ['--system']
+        if is_silent:
+            args += ['--silent']
+        args = get_parser().parse_args(args=args)
+        download(args)
+
+        args = ['download', url2]
+        if is_system:
+            args += ['--system']
+        if is_silent:
+            args += ['--silent']
+        args = get_parser().parse_args(args=args)
+        # download from url2 should be aborted.
+        with self.assertRaises(FileExistsError):
+            download(args)
+
+        # check download from url1 is not overwritten
+        result = {}
+        if os.path.exists('test'):
+            for name in os.listdir('test'):
+                with open(os.path.join('test', name)) as fh:
+                    result[name] = hashlib.md5(fh.buffer.read()).hexdigest()
+        self.assertEqual(files, result)

tests/command_download_invalid.py

@@ -8,5 +8,25 @@ class DownloadInvalid(unittest.TestCase):
     def snippet_call_download_raises(self, *args, **kwargs):
         tests.command_download.snippet_call_download_raises(self, *args, **kwargs)
 
+    def snippet_call_download_twice(self, *args, **kwargs):
+        tests.command_download.snippet_call_download_twice(self, *args, **kwargs)
+
     def test_call_download_invalid(self):
         self.snippet_call_download_raises(requests.exceptions.InvalidURL, 'https://not_exist_contest.jp/tasks/001_a')
+
+    def test_call_download_twice(self):
+        self.snippet_call_download_twice('https://atcoder.jp/contests/abc114/tasks/abc114_c',
+                                         'https://atcoder.jp/contests/abc003/tasks/abc003_4', [
+            {
+                "input": "575\n",
+                "output": "4\n"
+            },
+            {
+                "input": "3600\n",
+                "output": "13\n"
+            },
+            {
+                "input": "999999999\n",
+                "output": "26484\n"
+            },
+        ], type = 'json')