Asynchronous polyglot unit testing.

Introduction

Vertx Unit is designed for writing asynchronous unit tests with a polyglot API and running these tests in the JVM. Vertx Unit Api borrows from existing test frameworks like JUnit or QUnit and follows the Vert.x practices.

As a consequence Vertx Unit is the natural choice for testing Vert.x applications.

It can be used in different ways and run anywhere your code runs, it is just a matter of reporting the results the right way, this example shows the bare minimum test suite:

var TestSuite = require("vertx-unit-js/test_suite");
var suite = TestSuite.create("the_test_suite");
suite.test("my_test_case", function (context) {
  var s = "value";
  context.assertEquals("value", s);
});
suite.run();

The method will execute the suite and go through all the tests of the suite. The suite can fail or pass, this does not matter if the outer world is not aware of the test result.

var TestSuite = require("vertx-unit-js/test_suite");
var suite = TestSuite.create("the_test_suite");
suite.test("my_test_case", function (context) {
  var s = "value";
  context.assertEquals("value", s);
});
suite.run({
  "reporters" : [
    {
      "to" : "console"
    }
  ]
});

When executed, the test suite now reports to the console the steps of the test suite:

Begin test suite the_test_suite
Begin test my_test
Passed my_test
End test suite the_test_suite , run: 1, Failures: 0, Errors: 0

The option configures the reporters used by the suite runner for reporting the execution of the tests, see the Running section for more info.

Writing a test suite

A test suite is a named collection of test case, a test case is a straight callback to execute. The suite can have lifecycle callbacks to execute before and/or after the test cases or the test suite that are used for initializing or disposing services used by the test suite.

var TestSuite = require("vertx-unit-js/test_suite");
var suite = TestSuite.create("the_test_suite");
suite.test("my_test_case_1", function (context) {
  // Test 1
});
suite.test("my_test_case_2", function (context) {
  // Test 2
});
suite.test("my_test_case_3", function (context) {
  // Test 3
});

The API is fluent and therefore the test cases can be chained:

var TestSuite = require("vertx-unit-js/test_suite");
var suite = TestSuite.create("the_test_suite");
suite.test("my_test_case_1", function (context) {
  // Test 1
}).test("my_test_case_2", function (context) {
  // Test 2
}).test("my_test_case_3", function (context) {
  // Test 3
});

The test cases declaration order is not guaranteed, so test cases should not rely on the execution of another test case to run. Such practice is considered as a bad one.

Vertx Unit provides before and after callbacks for doing global setup or cleanup:

var TestSuite = require("vertx-unit-js/test_suite");
var suite = TestSuite.create("the_test_suite");
suite.before(function (context) {
  // Test suite setup
}).test("my_test_case_1", function (context) {
  // Test 1
}).test("my_test_case_2", function (context) {
  // Test 2
}).test("my_test_case_3", function (context) {
  // Test 3
}).after(function (context) {
  // Test suite cleanup
});

The declaration order of the method does not matter, the example declares the before callback before the test cases and after callback after the test cases but it could be anywhere, as long as it is done before running the test suite.

The before callback is executed before any tests, when it fails, the test suite execution will stop and the failure is reported. The after callback is the last callback executed by the testsuite, unless the before callback reporter a failure.

Likewise, Vertx Unit provides the beforeEach and afterEach callback that do the same but are executed for each test case:

var TestSuite = require("vertx-unit-js/test_suite");
var suite = TestSuite.create("the_test_suite");
suite.beforeEach(function (context) {
  // Test case setup
}).test("my_test_case_1", function (context) {
  // Test 1
}).test("my_test_case_2", function (context) {
  // Test 2
}).test("my_test_case_3", function (context) {
  // Test 3
}).afterEach(function (context) {
  // Test case cleanup
});

The beforeEach callback is executed before each test case, when it fails, the test case is not executed and the failure is reported. The afterEach callback is the executed just after the test case callback, unless the beforeEach callback reported a failure.

Asserting

Vertx Unit provides the TestContext object for doing assertions in test cases. The context object provides the usual methods when dealing with assertions.

assertEquals

Assert two objects are equals, works for basic types or json types.

suite.test("my_test_case", function (context) {
  context.assertEquals(10, callbackCount);
});

There is also an overloaded version for providing a message:

suite.test("my_test_case", function (context) {
  context.assertEquals(10, callbackCount, "Should have been 10 instead of " + callbackCount);
});

Usually each assertion provides an overloaded version.

assertNotEquals

The counter part of assertEquals.

suite.test("my_test_case", function (context) {
  context.assertNotEquals(10, callbackCount);
});

assertNull

Assert an object is null, works for basic types or json types.

suite.test("my_test_case", function (context) {
  context.assertNull(null);
});

assertNotNull

The counter part of assertNull.

suite.test("my_test_case", function (context) {
  context.assertNotNull("not null!");
});

assertInRange

The assertInRange targets real numbers.

suite.test("my_test_case", function (context) {

  // Assert that 0.1 is equals to 0.2 +/- 0.5

  context.assertInRange(0.1, 0.2, 0.5);
});

assertTrue and assertFalse

Asserts the value of a boolean expression.

suite.test("my_test_case", function (context) {
  context.assertTrue(var);
  context.assertFalse(value > 10);
});

Failing

Last but not least, test provides a fail method that will throw an assertion error:

suite.test("my_test_case", function (context) {
  context.fail("That should never happen");
  // Following statements won't be executed
});

Asynchronous testing

The previous examples supposed that test cases were terminated after their respective callbacks, this is the default behavior of a test case callback. Often it is desirable to terminate the test after the test case callback, for instance:

The Async object asynchronously completes the test case
suite.test("my_test_case", function (context) {
  var async = context.async();
  eventBus.consumer("the-address", function (msg) {
    (2)
    async.complete();
  });
  (1)
});
  1. The callback exits but the test case is not terminated

  2. The event callback from the bus terminates the test

Creating an Async object with the async method marks the executed test case as non terminated. The test case terminates when the complete method is invoked.

Note
When the complete callback is not invoked, the test case fails after a certain timeout.

Several Async objects can be created during the same test case, all of them must be completed to terminate the test.

Several Async objects provide coordination
suite.test("my_test_case", function (context) {

  var async1 = context.async();
  var client = vertx.createHttpClient();
  var req = client.get(8080, "localhost", "/");
  req.exceptionHandler(function (err) {
    context.fail(err.getMessage())});
  req.handler(function (resp) {
    context.assertEquals(200, resp.statusCode());
    async1.complete();
  });
  req.end();

  var async2 = context.async();
  vertx.eventBus().consumer("the-address", function (msg) {
    async2.complete();
  });
});

Async objects can also be used in before or after callbacks, it can be very convenient in a before callback to implement a setup that depends on one or several asynchronous results:

Async starts an http server before test cases
suite.before(function (context) {
  var async = context.async();
  var server = vertx.createHttpServer();
  server.requestHandler(requestHandler);
  server.listen(8080, function (ar, ar_err) {
    context.assertTrue(ar_err == null);
    async.complete();
  });
});

Sharing objects

The TestContext has get/put/remove operations for sharing state between callbacks.

Any object added during the before callback is available in any other callbacks. Each test case will operate on a copy of the shared state, so updates will only be visible for a test case.

Sharing state between callbacks
var TestSuite = require("vertx-unit-js/test_suite");
TestSuite.create("my_suite").before(function (context) {

  // host is available for all test cases
  context.put("host", "localhost");

}).beforeEach(function (context) {

  // Generate a random port for each test
  var port = helper.randomPort();

  // Get host
  var host = context.get("host");

  // Setup server
  var async = context.async();
  var server = vertx.createHttpServer();
  server.requestHandler(function (req) {
    req.response().setStatusCode(200).end();
  });
  server.listen(port, host, function (ar, ar_err) {
    context.assertTrue(ar_err == null);
    context.put("port", port);
    async.complete();
  });

}).test("my_test", function (context) {

  // Get the shared state
  var port = context.get("port");
  var host = context.get("host");

  // Do request
  var client = vertx.createHttpClient();
  var req = client.get(port, host, "/resource");
  var async = context.async();
  req.handler(function (resp) {
    context.assertEquals(200, resp.statusCode());
    async.complete();
  });
  req.end();
});
Warning
sharing any object is only supported in Java, other languages can share only basic or json types. Other objects should be shared using the features of that language.

Running

When a test suite is created, it won’t be executed until the run method is called.

Running a test suite
suite.run();

The test suite can also be ran with a specified Vertx instance:

Provides a Vertx instance to run the test suite
suite.run(vertx);

When running with a Vertx instance, the test suite is executed using the Vertx event loop, see the [eventloop] section for more details.

Test suite completion

No assumptions can be made about when the test suite will be completed, and if some code needs to be executed after the test suite, it should either be in the test suite after callback or as callback of the TestCompletion:

Test suite execution callback
var completion = suite.run(vertx);

// Simple completion callback
completion.handler(function (ar, ar_err) {
  if (ar_err == null) {
    console.log("Test suite passed!");
  } else {
    console.log("Test suite failed:");
    ar_err.printStackTrace();
  };
});

The TestCompletion object provides also a resolve method that takes a Future object, this Future will be notified of the test suite execution:

Resolving the start Future with the test suite
var completion = suite.run();

// When the suite completes, the future is resolved
completion.resolve(startFuture);

This allow to easily create a test verticle whose deployment is the test suite execution, allowing the code that deploys it to be easily aware of the success or failure.

The completion object can also be used like a latch to block until the test suite completes. This should be used when the thread running the test suite is not the same than the current thread:

Blocking until the test suite completes
var completion = suite.run();

// Wait until the test suite completes
completion.await();

The await throws an exception when the thread is interrupted or a timeout is fired.

The awaitSuccess is a variation that throws an exception when the test suite fails.

Blocking until the test suite succeeds
var completion = suite.run();

// Wait until the test suite succeeds otherwise throw an exception
completion.awaitSuccess();

Time out

Each test case of a test suite must execute before a certain timeout is reached. The default timeout is of 2 minutes, it can be changed using test options:

Setting the test suite timeout
var options = {
  "timeout" : 10000
};

// Run with a 10 seconds time out
suite.run(options);

Event loop

Vertx Unit execution is a list of tasks to execute, the execution of each task is driven by the completion of the previous task. These tasks should leverage Vert.x event loop when possible but that depends on the current execution context (i.e the test suite is executed in a main or embedded in a Verticle) and wether or not a Vertx instance is configured.

The useEventLoop configures the usage of the event loop:

Table 1. Event loop usage
useEventLoop:null useEventLoop:true useEventLoop:false

Vertx instance

use vertx event loop

use vertx event loop

force no event loop

in a Verticle

use current event loop

use current event loop

force no event loop

in a main

use no event loop

raise an error

use no event loop

The default useEventLoop value is null, that means that it will uses an event loop when possible and fallback to no event loop when no one is available.

Reporting

Reporting is an important piece of a test suite, Vertx Unit can be configured to run with different kind of reporters.

By default no reporter is configured, when running a test suite, test options can be provided to configure one or several:

Using the console reporter and as a junit xml file
// Report to console
var consoleReport = {
  "to" : "console"
};

// Report junit files to the current directory
var junitReport = {
  "to" : "file:.",
  "format" : "junit"
};

suite.run({
  "reporters" : [
    consoleReport,
    junitReport
  ]
});

Console reporting

Reports to the JVM System.out and System.err:

to

console

format

simple or junit

File reporting

Reports to a file, a Vertx instance must be provided:

to

file : dir name

format

simple or junit

example

file:.

The file reporter will create files in the configured directory, the files will be named after the test suite name executed and the format (i.e simple creates txt files and junit creates xml files).

Log reporting

Reports to a logger, a Vertx instance must be provided:

to

log : logger name

example

log:mylogger

Event bus reporting

Reports events to the event bus, a Vertx instance must be provided:

to

bus : event bus address

example

bus:the-address

It allow to decouple the execution of the test suite from the reporting.

The messages sent over the event bus can be collected by the EventBusCollector and achieve custom reporting:

var EventBusCollector = require("vertx-unit-js/event_bus_collector");
var collector = EventBusCollector.create(vertx, {
  "reporters" : [
    {
      "to" : "file:report.xml",
      "format" : "junit"
    }
  ]
});

collector.register("the-address");

Junit integration

Although Vertx Unit is polyglot and not based on JUnit, it is possible to run a Vertx Unit test suite or a test case from JUnit, allowing you to integrate your tests with JUnit and your build system or IDE.

Run a Java class as a JUnit test suite
RunWith(io.vertx.ext.unit.junit.VertxUnitRunner.class)
public class JUnitTestSuite {

  Test
  public void testSomething(Context context) {
    context.assertFalse(false);
  }
}

The VertxUnitRunner uses the junit annotations for introspecting the class and create a test suite after the class. The methods should declare a TestContext argument, if they don’t it is fine too. However the TestContext is the only way to retrieve the associated Vertx instance of perform asynchronous tests.

A single test case can also be executed with a TestCase:

Run a test case in a JUnit test
TestCase.
  create("my_test_case", context -> {
    context.assertTrue(true);
  }).
  awaitSuccess(); (1)
  1. Block until the test case is executed

Java language integration

The Java language provides classes and it is possible to create test suites directly from Java classes with the following mapping rules:

The argument methods are inspected and the public, non static methods with TestContext parameter are retained and mapped to a Vertx Unit test suite via the method name:

  • before : before callback

  • after : after callback

  • beforeEach : beforeEach callback

  • afterEach : afterEach callback

  • when the name starts with test : test case callback named after the method name

Test suite written using a Java class
public class MyTestSuite {

  public void testSomething(TestContext context) {
    context.assertFalse(false);
  }
}

This class can be turned into a Vertx test suite easily:

Create a test suite from a Java object
TestSuite suite = TestSuite.create(new MyTestSuite());