Android Testing
JUnit, Espresso, unit tests, instrumented tests, assertions
1What is JUnit?
What is JUnit?
回答
JUnit is a unit testing framework for Java and Kotlin. It's the standard for writing and executing automated tests. JUnit 4 uses annotations (@Test, @Before, @After) to define tests and their lifecycle. JUnit tests are fast because they run on the local JVM without Android emulator.
2What is the @Test annotation used for?
What is the @Test annotation used for?
回答
@Test marks a method as a unit test. The method will be executed by the test runner. Without @Test, the method is ignored. Example: @Test fun testAddition() { assertEquals(4, 2 + 2) }. Each @Test must be independent and not depend on execution order.
3What is the @Before annotation used for?
What is the @Before annotation used for?
回答
@Before marks a method that executes BEFORE each test (@Test). Useful for initializing common objects, creating mocks, resetting state. Example: @Before fun setUp() { viewModel = MyViewModel() }. If you have 5 tests, @Before runs 5 times. Alternative: @BeforeClass for single execution before all tests.
What is the @After annotation used for?
What is an assertion in testing?
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