Unit Testing

• Helps in catching bugs.
• Testing smallest piece of code.
• Helps in writing modular codes - features can be added easily.

Testing in Android -

• We have kotlin/java code (Pure Logic) with Android Framework.
• Having a good architecture helps in seggregating Android Code from pure kotlin/java logic.

Two types of tests -

• Unit Tests ->
  • JVM Test (Local Unit Tests)
  • On Device Tests (Instrumentation Tests)
    • Instrumentation Tests can also be classified in two types ->
    • UI Tests (Interaction With Views)
    • Non UI Tests (Context, Assset MAnager etc.)

JUnit Test Example

Unit Tests example Using JUnit

@Test
fun isPalindrome_inputString_level_expectedTrue() {
    // Arrange - initialize the class object
    val helper = Helper()
    // Act - call the function
    val result = helper.isPalindrome("level")
    // Assert - compare to Test
    assertEquals(true, result)
}

We use Parameterized Test for multiple test cases!

• Define a class for Parameterized Tests.
• Define class Parameters for your input string, and Expected Value
• See the ParameterizedExample class for better understanding!

Here we have completed the part of JUnit tests, Now let's talk about Instrumentation Tests.

Instrumentation Tests Example

How to write Instrumentation tests that do not interact with UI. Classes such as Android Context, Asset Manager do not need UI to work with. To write test cases for these classes we need to write instrumentation test. These test cases follow the same pattern as JUnit. ** There are two types of Instrumentation Tests are available -**

• Non UI (Similar to Unit Tests)
• UI (Expresso)

Now Let's Practice some problems related to Local unit test.

Problem statements

• Validate password
  • Should not be Empty
  • Lenth should be between 6 to 15
  • OtherWise return valid password
• String reversal.

Espresso - Tests for UI interactions

• Learn how to write unit test cases in android that checks your UI logic. Espresso helps to write automated test cases for Android. Espresso tests UI interaction, state assertions and expectations in Android.

• Learn how to use different matchers to access views and interact with them. Learn about ViewInteractions and ViewActions class. Learn how to use onView, withId, withText, perform methods to interact with Android Views. Learn how to use Espresso Intent Library to write test cases for Intent based scenarios. For example - Intent Chooser for ACTION_SEND.

• Learn how to use activityScenarioRule to open activity to test UI interactions. These test cases follow the same pattern as JUnit. Learn how to write these Instrumentation tests in Android with simple example.

CheckOut this repository -> Quote MvvM where i've implemented the Espresso Test.