xUnit

很多unit testing framework都是基于这个framework。

wikipedia xUnit

xUnit architecture

NOTE: architecture这对于我们掌握unit testing framework非常重要；xUnit的architecture是非常经典的。

它是典型的multiple-task model的。

All xUnit frameworks share the following basic component architecture, with some varied implementation details.[1]

Test runner

A test runner is an executable program that runs tests implemented using an xUnit framework and reports the test results.[2]

Test case

A test case is the most elemental class. All unit tests are inherited from here.

Test fixtures

NOTE: "fixture"在此的含义是"装配"，在下面使用的是context是，显然context的含义是更加准确的。

为什么"return to the original state after the tests"？

因为要执行多个test，"return to the original state"能够保证后续的test能够继续执行。

在后面的"test execution"章节将对它有更好的描述。

A test fixture (also known as a test context) is the set of preconditions or state needed to run a test. The developer should set up a known good state before the tests, and return to the original state after the tests.

Test suites

A test suite is a set of tests that all share the same fixture. The order of the tests shouldn't matter.

Test execution

The execution of an individual unit test proceeds as follows:

setup(); /* First, we should prepare our 'world' to make an isolated environment for testing */
...
/* Body of test - Here we make all the tests */
...
teardown(); /* At the end, whether we succeed or fail, we should clean up our 'world' to 
not disturb other tests or code */

The setup() and teardown() methods serve to initialize and clean up test fixtures.

NOTE:

setup()

teardown()

Test result formatter

A test runner produces results in one or more output formats. In addition to a plain, human-readable format, there is often a test result formatter that produces XML output.

Assertions

An assertion is a function or macro that verifies the behavior (or the state) of the unit under test. Usually an assertion expresses a logical condition that is true for results expected in a correctly running system under test (SUT). Failure of an assertion typically throws an exception, aborting the execution of the current test.