Make ClientRequestBase mock friendly

[jbescos]

Description

I was mocking WebClient and I found some issues related to null pointers and unable to mock relevant methods.

This was the method I had:

    private WebClient mockWebClient(Status status) {
        WebClient webClient = Mockito.mock(WebClient.class);
        HttpClientRequest request = Mockito.mock(HttpClientRequest.class);
        HttpClientResponse response = Mockito.mock(HttpClientResponse.class);
        doReturn(request).when(webClient).post(anyString());
        doReturn(request).when(request).header(any(HeaderName.class), anyString());
        doReturn(response).when(request).submit(any(Object.class));
        doReturn(OpenAiChatResponse.create(null, null, 0, null, null, null, List.of(), null)).when(response).as(OpenAiChatResponse.class);
        when(response.status()).thenReturn(status);
        return webClient;
    }

Some issues:

java.lang.NullPointerException: Cannot invoke "io.helidon.http.Method.equals(Object)" because "this.method" is null
	at io.helidon.webclient.api.ClientRequestBase.rejectHeadWithEntity(ClientRequestBase.java:484)
	at io.helidon.webclient.api.ClientRequestBase.submit(ClientRequestBase.java:267)
	at io.helidon.ai.openai.OpenAiChatClientTest.mockWebClient(OpenAiChatClientTest.java:66)

Invalid use of argument matchers!
0 matchers expected, 1 recorded:
-> at io.helidon.ai.openai.OpenAiChatClientTest.mockWebClient(OpenAiChatClientTest.java:67)

This exception may occur if matchers are combined with raw values:
    //incorrect:
    someMethod(anyObject(), "raw String");
When using matchers, all arguments have to be provided by matchers.
For example:
    //correct:
    someMethod(anyObject(), eq("String by matcher"));

For more info see javadoc for Matchers class.

	at io.helidon.webclient.api.ClientRequestBase.submit(ClientRequestBase.java:269)
	at io.helidon.ai.openai.OpenAiChatClientTest.mockWebClient(OpenAiChatClientTest.java:67)

Documentation

NA

[romain-grecourt]

This needs a test.

[jbescos]

I have added a test. This is without the head fix:

[ERROR] io.helidon.webclient.tests.WebClientMockTest.useMock  Time elapsed: 0.287 s  <<< ERROR!
java.lang.NullPointerException: Cannot invoke "io.helidon.http.Method.equals(Object)" because "this.method" is null
	at io.helidon.webclient.api.ClientRequestBase.rejectHeadWithEntity(ClientRequestBase.java:484)
	at io.helidon.webclient.api.ClientRequestBase.submit(ClientRequestBase.java:267)
	at io.helidon.webclient.tests.WebClientMockTest.mockWebClient(WebClientMockTest.java:54)
	at io.helidon.webclient.tests.WebClientMockTest.useMock(WebClientMockTest.java:41)

And this is without the final remove:

[ERROR] io.helidon.webclient.tests.WebClientMockTest.useMock  Time elapsed: 0.296 s  <<< ERROR!
org.mockito.exceptions.misusing.InvalidUseOfMatchersException: 

Invalid use of argument matchers!
0 matchers expected, 1 recorded:
-> at io.helidon.webclient.tests.WebClientMockTest.mockWebClient(WebClientMockTest.java:54)

This exception may occur if matchers are combined with raw values:
    //incorrect:
    someMethod(anyObject(), "raw String");
When using matchers, all arguments have to be provided by matchers.
For example:
    //correct:
    someMethod(anyObject(), eq("String by matcher"));

For more info see javadoc for Matchers class.

	at io.helidon.webclient.api.ClientRequestBase.submit(ClientRequestBase.java:269)
	at io.helidon.webclient.tests.WebClientMockTest.mockWebClient(WebClientMockTest.java:54)
	at io.helidon.webclient.tests.WebClientMockTest.useMock(WebClientMockTest.java:41)

@tomas-langer @romain-grecourt could you approve this before the new release of Helidon?. We need it for AI.