client: fix TestPingWithError

This test was added in 27ef09a46ffeb8ba42548de937b68351009f30ea, which changed
the Ping handling to ignore internal server errors. That case is tested in
TestPingFail, which verifies that we accept the Ping response if a 500
status code was received.

The TestPingWithError test was added to verify behavior if a protocol
(connection) error occurred; however the mock-client returned both a
response, and an error; the error returned would only happen if a connection
error occurred, which means that the server would not provide a reply.

Running the test also shows that returning a response is unexpected, and
ignored:

    === RUN   TestPingWithError
    2024/02/23 14:16:49 RoundTripper returned a response & error; ignoring response
    2024/02/23 14:16:49 RoundTripper returned a response & error; ignoring response
    --- PASS: TestPingWithError (0.00s)
    PASS

This patch updates the test to remove the response.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

client/ping_test.go

@@ -53,18 +53,12 @@ func TestPingFail(t *testing.T) {
 func TestPingWithError(t *testing.T) {
 	client := &Client{
 		client: newMockClient(func(req *http.Request) (*http.Response, error) {
-			resp := &http.Response{StatusCode: http.StatusInternalServerError}
-			resp.Header = http.Header{}
-			resp.Header.Set("API-Version", "awesome")
-			resp.Header.Set("Docker-Experimental", "true")
-			resp.Header.Set("Swarm", "active/manager")
-			resp.Body = io.NopCloser(strings.NewReader("some error with the server"))
-			return resp, errors.New("some error")
+			return nil, errors.New("some connection error")
 		}),
 	}
 
 	ping, err := client.Ping(context.Background())
-	assert.Check(t, is.ErrorContains(err, "some error"))
+	assert.Check(t, is.ErrorContains(err, "some connection error"))
 	assert.Check(t, is.Equal(false, ping.Experimental))
 	assert.Check(t, is.Equal("", ping.APIVersion))
 	var si *swarm.Status