Add test for do not prompt when --no-input flag is given

tests/functional/test_no_input_arguement.py

@@ -0,0 +1,27 @@
+from pip._internal.cli.base_command import ERROR
+from tests.lib.server import (
+    authorization_response,
+    make_mock_server,
+    server_running,
+)
+
+
+def test_do_not_prompt_when_no_input_flag_given(script):
+    server = make_mock_server()
+    server.mock.side_effect = [
+        authorization_response(),
+    ]
+
+    url = "https://{}:{}/simple".format(server.host, server.port)
+
+    args = ["install"]
+    args.extend(["--index-url", url])
+    args.append("requests")
+    args.append("--no-input")
+
+    with server_running(server):
+        result = script.pip(*args, expect_error=True)
+
+    assert "Could not find a version that satisfies the" in result.stderr
+    assert "No matching distribution found for requests" in result.stderr
+    assert result.returncode == ERROR

tests/lib/server.py

@@ -81,6 +81,7 @@ def _mock_wsgi_adapter(mock):
     """Uses a mock to record function arguments and provide
     the actual function that should respond.
     """
+
     def adapter(environ, start_response):
         # type: (Environ, StartResponse) -> Body
         responder = mock(environ, start_response)
@@ -210,3 +211,14 @@ def responder(environ, start_response):
             return [f.read()]
 
     return responder
+
+
+def authorization_response():
+    def responder(environ, start_response):
+        start_response(
+            "401 Unauthorized", [
+                ("WWW-Authenticate", "Basic"),
+            ],
+        )
+
+    return responder