# Espresso Dependency
###### tags: `Android Dependency`

[TOC]

# What is it for?
It is used to do **unit testing on UI Views** (like [UI Automator](https://developer.android.com/training/testing/ui-automator)).
It enable us to:
* Look for some views
* Control views
* Compare views

# Dependency
Actually it should be there when you create a project, unless you deleted it.

## build.gradle(:app) dependency and setting
**build.gradle (:app)**

//Espresso
testImplementation 'junit:junit:4.13.2'

androidTestImplementation 'androidx.test.ext:junit:1.1.3'
androidTestImplementation 'androidx.test:runner:1.4.0'
androidTestImplementation 'androidx.test:rules:1.4.0'
androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'

**testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"**

defaultConfig {
    applicationId "com.zc.androiddependencies"
    minSdkVersion 16
    targetSdkVersion 30
    versionCode 1
    versionName "1.0"

    //Multidex Enable here only works for >= 21 sdks
    multiDexEnabled true

    testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
}

>**Note:**
>JUnit is a testing framework for Java. [color=pink]

## What is androidTestImplementation?
>Remember the folders below /src?
>We have **/main, /test and /androidTest**
>androidTestImplementation just deals with /androidTest dependency settings.[color=orange]

# How to use Espresso?

## Espresso Tools
1. **ViewMatcher: Find Views**
Ex: withId、withText
1. **ViewAction: Control views' actions**
Ex: click、typeText
1. **ViewAssertion: Compares View**
Ex: matches

## Steps towards Espresso UI Test base file
### 1. [Add dependencies in build.gradle](#Dependency)

### 2. New a Test class in androidTest Folder
>**Note:** The class **MUST BE ++PUBLIC++** or else you will get Class not found/ class is not a test/ etc.[color=red]

**Example:**

### 3. Write your test

## How to write a Test?
### Introduction
Things to take into account:

* **Annotations**
* @Rule: For ActivityScenarioRule.
* @Before: Actions before test.
* @Test: The test method itself.
* **ActivityScenarioRule:** Is used to find the activity in which you want to proceed the test on.

### Let's check an example directly!
**Example**
<details>
<summary>Dependencies</summary>
import androidx.test.ext.junit.rules.ActivityScenarioRule;
import androidx.test.ext.junit.runners.AndroidJUnit4;
import androidx.test.filters.LargeTest;
import com.zc.androiddependencies.espresso.EspressoActivity;
import org.junit.Before;
import org.junit.Rule;
import org.junit.Test;
import org.junit.runner.RunWith;
import static androidx.test.espresso.Espresso.onView;
import static androidx.test.espresso.action.ViewActions.clearText;
import static androidx.test.espresso.action.ViewActions.click;
import static androidx.test.espresso.action.ViewActions.typeText;
import static androidx.test.espresso.assertion.ViewAssertions.matches;
import static androidx.test.espresso.matcher.ViewMatchers.isEnabled;
import static androidx.test.espresso.matcher.ViewMatchers.isNotEnabled;
import static androidx.test.espresso.matcher.ViewMatchers.withId;
</details>

package com.zc.androiddependencies;

@RunWith(AndroidJUnit4.class)
@LargeTest
public class EspressoActivityTest {

     public String input;

    //Tells which activity you are performing the test on.
    @Rule
    public ActivityScenarioRule<EspressoActivity> activityRule = new ActivityScenarioRule<>(EspressoActivity.class);

    //Actions before test
    @Before
    public void stringToBeTyped(){
        input = "Espresso Test";
    }

    @Test
    public void checkSubmitState(){
        //Check Submit Button is not enabled
        onView(withId(R.id.btn_submit))
                .check(matches(isNotEnabled()));

        //Test type into EditText
        onView(withId(R.id.et_account))
                .perform(typeText(input));

        //Check Submit Button is enabled
        onView(withId(R.id.btn_submit))
                .check(matches(isEnabled()));

        //Check Submit Button is clickable
        onView(withId(R.id.btn_submit))
                .perform(click());

        //Clear Text
        onView(withId(R.id.et_account))
                .perform(clearText());

        //Check Submit Button is not enabled
        onView(withId(R.id.btn_submit))
                .check(matches(isNotEnabled()));


    }
    
    //ViewAssertions: matches
    //ViewMatchers: isNotEnabled
    //ViewActions: clearText/click/typeText
    //ViewInteraction: check/perform

}

**Activity**

public class EspressoActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_espresso);

        EditText etAccount = findViewById(R.id.et_account);
        Button btnSubmit = findViewById(R.id.btn_submit);
        btnSubmit.setEnabled(false);
        etAccount.addTextChangedListener(new SimplifyTextWatcher() {
            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {
                btnSubmit.setEnabled(s != null && s.length() > 0);
            }
        });

    }
}

**Note:**
**ActivityTestRule** is deprecated so better use **ActivityScenarioRule**.

## How to run test?
### Run by clicking run
>[color=lightblue]

### Add Test in Edit Configuration
>[color=lightblue]
**Note:** If you cannot run test, you may as well delete all tests and new them again.

# Reference
[Espresso Article in CH](https://ithelp.ithome.com.tw/articles/10227511)
[Android Studio Espresso](https://developer.android.com/training/testing/ui-testing/espresso-testing)