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PGSSoft / HttpClientMock

Library for mocking Java 11 HttpClient.
MIT License
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httpclient java mock test unit-testing

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HttpClientMock

HttpClientMock is a library for mocking Java HttpClient. It has an intuitive fluent API for defining client behaviour and verifing number of made requests.

Installation

HttpClientMock is available in Maven Central Repository.

<dependency>
    <groupId>com.pgs-soft</groupId>
    <artifactId>HttpClientMock</artifactId>
    <version>1.0.0</version>
</dependency>

Requirements

Usage

Record

Working with HttpClientMock starts with defining client behaviour. Before code under tests starts HttpClientMock must know how to respond to every request.

HttpClientMock httpClientMock = new HttpClientMock();
httpClientMock.onGet("http://localhost/login")
  .withParameter("user","john")
  .doReturn("Ok");
httpClientMock.onPost("http://localhost/login").doReturnStatus(501);

Replay

Code under test starts and uses HttpClientMock with defined behaviour.

var get = HttpRequest.newBuilder(URI.create("http://localhost/login?user:john")).GET().build();
var post = HttpRequest.newBuilder(URI.create("http://localhost/login")).POST(noBody()).build();
httpClient.send(get, ofString()); // returns response with body "Ok"
httpClient.send(post, ofString()); // returns response with status 501

Verify

When code under test finishes, HttpClientMock allows to check number of made request. It is possible to use the same set of conditions as for defining mock behaviour.

httpClientMock.verify().get("http://localhost/login").withParameter("user","john").called()
httpClientMock.verify().post("http://localhost/login").notCalled()

Request matching

HTTP method

HttpClientMock supports all Http methods.

httpClientMock.onGet().doReturn("get");
httpClientMock.onPost().doReturn("post");
httpClientMock.onPut().doReturn("put");
httpClientMock.onDelete().doReturn("delete");
httpClientMock.onOptions().doReturn("options");
httpClientMock.onHead().doReturn("head");

URL

Every onGet(), onPost(), .... method accept URL. It is possible to write:

httpClientMock.onGet("http://localhost/login?user=john").doReturnStatus(200);

which is equal to

httpClientMock.onGet()
  .withHost("httt://locahost")
  .withPath("/login")
  .withParameter("user","john")
  .doReturnStatus(200);

It is possible to define default host using HttpClientMock constructor, so later methods can accept relative URL-s.

HttpClientMock httpClientMock = new HttpClientMock("http://localhost");
httpClientMock.onGet("/login").doReturn("ok");
httpClientMock.onPost("/edit?user=john").doReturnStatus(200);

httpClientMock.onGet("http://www.google.com").doReturn("Google") // Absolute paths still work.

Host, path, parameters, reference conditions

It is possible to define each part of url separately.

httpClientMock.onGet()
  .withHost("httt://locahost")
  .withPath("/login")
  .withParameter("user","john")
  .withReference("edit")
  .doReturnStatus(200);

Header condition

httpClientMock.onGet("http://localhost/login")
  .withHeader("tracking","123")
  .doReturn("ok");

Body condition

httpClientMock.onGet("http://localhost/login")
  .withBody("tracking",containsString(123))
  .doReturn("ok");

Custom condition

Condition fooCondition = request -> request.getUri().contains("foo");
httpClientMock.onGet("http://localhost/foo/bar")
  .with(fooCondition)
  .doReturn("yes");

Matchers

Every condition method accepts Hamcrest Matcher which allows to define custom conditions on requests.

httpClientMock.onGet("http://localhost")
  .withPath(containsString("login"))
  .withParameter("user",equalToIgnoringCase("John)")
  .reference(not(equalTo("edit")));

Multiple matching rules

If request matches more then one rule, then last defined one is used.

None rule matche

If request doesn't matche any rule, HttpClientMock return response with status 404.

Define response

Response

Response with provided body and status 200.

httpClientMock.onGet("http://localhost").doReturn("my response")

Status

Response with empty body and provided status

httpClientMock.onGet("http://localhost").doReturnStatus(300)
httpClientMock.onGet("http://localhost").doReturn("Overloaded").withStatus("500");

Exception

Instead of returning response it throws defined exception.

httpClientMock.onGet("http://localhost").doThrowException(new IOException());

Custom action

Action echo r -> {
  HttpEntity entity = ((HttpEntityEnclosingRequestBase) r.getHttpRequest()).getEntity();
  BasicHttpResponse response = new BasicHttpResponse(new ProtocolVersion("http", 1, 1), 200, "ok");
  response.setEntity(entity);
  return response;
};
httpClientMock.onGet("http://localhost").doAction(echo);

Response header

httpClientMock.onPost("/login").doReturn("foo").withHeader("tracking", "123")

Response status

httpClientMock.onPost("/login?user=bar").doReturn("Wrong user").withStatus(403)

JSON

Response with provided body, status 200 and content type "application/json"

httpClientMock.onPost("/login").doReturnJSON("{foo:1}");

XML

Response with provided body, status 200 and content type "application/xml"

httpClientMock.onPost("/login").doReturnXML("<foo>bar</foo>");

Multiple actions

It is possible to add multiple actions to one rule. Every call will use next action until last is reached.

httpClientMock.onPut("/addUser")
  .doReturn("ok");
  .doReturnStatus(500);

var req = HttpRequest.newBuilder(URI.create("http://localhost/addUser")).PUT(noBody()).build();
httpClientMock.send(req, ofString()); //returns "ok"
httpClientMock.send(req, ofString()); //returns status 500
httpClientMock.send(req, ofString()); //returns status 500

Verification

HttpClientMock allows to check how many calls were made. Verification supports the same set of conditions us rule defining.

httpClientMock.verify().get("http://localhost").called();

httpClientMock.verify().get("http://localhost/login")
  .withParameter("user","john")
  .called();

httpClientMock.verify().get("http://localhost/login")
  .withParameter("user","Ben")
  .notCalled();

httpClientMock.verify().delete().notCalled();

httpClientMock.verify().get().called(greaterThanOrEqualTo(1));

Examples

Example 1

// DEFINE BEHAVIOUR
HttpClientMock httpClientMock = new HttpClientMock("http://localhost:8080");
httpClientMock.onGet("/login?user=john").doReturnJSON("{permission:1}");
httpClientMock.onPost("/edit")
  .withParameter("user","John")
  .doReturn("ok")
  .doReturnStatus(503);

// EXECUTION
// request to http://localhost:8080/login?user=john returns JSON {permission:1}
// first request to http://localhost:8080/edit?user=john returns message "ok"
// second request to http://localhost:8080/edit?user=john returns request with status 503

// VERIFICATION
httpClientMock.verify().get("/login?user=john").called();
httpClientMock.verify().post("/edit?user=john").called(2);
httpClientMock.verify().delete().notCalled();

Example 2

// DEFINE BEHAVIOUR
HttpClientMock httpClientMock = new HttpClientMock();
httpClientMock.onGet("http://localhost:8080/login").doReturn("Missing parameter user").withStatus(400);
httpClientMock.onGet("http://localhost:8080/login")
  .withParameter("user","JJohn")
  .doReturn("Wrong user name").withStatus(403);
httpClientMock.onGet("http://localhost:8080/login")
  .withParameter("user","John")
  .doReturn("ok");

// EXECUTION
// request to http://localhost:8080/login?user=john returns message "ok"

// VERIFICATION
httpClientMock.verify().get("/login?user=john").called();

License

The project is available as open source under the terms of the MIT License.

About

The project maintained by software development agency PGS Software. See our other open-source projects or contact us to develop your product.

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