Added Google Truth Library and wrote unit and integrated test

Signed-off-by: Ramakrishna Joshi <ramakrishnaj995@gmail.com>

app/build.gradle

@@ -30,10 +30,18 @@ dependencies {
     implementation 'androidx.core:core-ktx:1.3.2'
     implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
 
-    //Android Specific Test
-    androidTestImplementation 'androidx.test.ext:junit:1.1.2'
-    androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0'
+    //testImplementation includes dependencies only for `test` source-set
+    //androidTestImplementation includes dependencies only for `androidTest` source-set
 
     //JUnit Test
     testImplementation 'junit:junit:4.13.1'
+    //Truth gives convenient methods which makes assertions in our test cases much more readable
+    testImplementation 'com.google.truth:truth:1.0.1'
+
+    //Android Specific Test
+    androidTestImplementation 'androidx.test.ext:junit:1.1.2'
+    androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0' //espresso is needed for UI Tests
+
+    //If truth dependency is also needed in `androidTest` source-set then we need to add below line
+    androidTestImplementation 'com.google.truth:truth:1.0.1'
 }

app/src/androidTest/java/com/example/unittestinginandroid/basicunittests/ResourceComparerTest.kt

@@ -0,0 +1,49 @@
+package com.example.unittestinginandroid.basicunittests
+
+import android.content.Context
+import androidx.test.core.app.ApplicationProvider
+import com.example.unittestinginandroid.R
+import com.google.common.truth.Truth.assertThat
+import org.junit.After
+import org.junit.Before
+import org.junit.Test
+
+class ResourceComparerTest {
+
+    lateinit var resourceComparer: ResourceComparer
+
+    @Before
+    fun setUp() {
+        resourceComparer = ResourceComparer()
+    }
+
+    @After
+    fun tearDown() {
+        //no need to do anything here as Garbage Collector will clean up resourceComparer automatically
+        //but in case if there is DatabaseConection object that that needs to be closed here
+    }
+
+    @Test
+    fun shouldReturnFalseIfStringsDontMatch() {
+        val context = ApplicationProvider.getApplicationContext<Context>()
+        val result = resourceComparer.isEqual(
+            context,
+            R.string.app_name,
+            "SomeRandomString"
+        )
+
+        assertThat(result).isFalse()
+    }
+
+    @Test
+    fun shouldReturnTrueIfStringsMatch() {
+        val context = ApplicationProvider.getApplicationContext<Context>()
+        val result = resourceComparer.isEqual(
+            context,
+            R.string.app_name,
+            "UnitTestingInAndroid"
+        )
+
+        assertThat(result).isTrue()
+    }
+}

app/src/main/java/com/example/unittestinginandroid/basicunittests/RegistrationUtil.kt

@@ -0,0 +1,34 @@
+package com.example.unittestinginandroid.basicunittests
+
+object RegistrationUtil {
+
+    private val existingUsers = listOf<String>("Ram", "Krishna")
+
+    /*
+    * input is not valid if...
+    * ...the userName is empty
+    * ...the userName is already taken
+    * ...the password or confirmedPassword is empty
+    * ...the confirmedPassword is not same as the real password
+    * ...the password does not contain at least 2 digits
+    * */
+    fun validateRegistrationInput(
+        userName: String,
+        password: String,
+        confirmedPassword: String
+    ): Boolean {
+        if (userName.isEmpty() || password.isEmpty() || confirmedPassword.isEmpty()) {
+            return false
+        }
+        if (existingUsers.contains(userName)) {
+            return false
+        }
+        if (password != confirmedPassword) {
+            return false
+        }
+        if (password.count { it.isDigit() } < 2) {
+            return false
+        }
+        return true
+    }
+}

app/src/main/java/com/example/unittestinginandroid/basicunittests/ResourceComparer.kt

@@ -0,0 +1,10 @@
+package com.example.unittestinginandroid.basicunittests
+
+import android.content.Context
+
+class ResourceComparer {
+
+    fun isEqual(context: Context, resId: Int, string: String): Boolean {
+        return context.getString(resId) == string
+    }
+}

app/src/test/java/com/example/unittestinginandroid/basicunittests/RegistrationUtilTest.kt

@@ -0,0 +1,73 @@
+package com.example.unittestinginandroid.basicunittests
+
+import com.google.common.truth.Truth.assertThat
+import org.junit.After
+import org.junit.Before
+import org.junit.Test
+
+class RegistrationUtilTest {
+
+    lateinit var sut: RegistrationUtil
+
+    @Before
+    fun setUp() {
+        sut = RegistrationUtil
+    }
+
+    @Test
+    fun `empty userName returns false`() {
+        val result = sut.validateRegistrationInput(
+            "",
+            "1234",
+            "1234"
+        )
+
+        assertThat(result).isFalse()
+    }
+
+    @Test
+    fun `should return false if userName is taken`() {
+        val result = sut.validateRegistrationInput(
+            "Ram",
+            "1234",
+            "1234"
+        )
+        assertThat(result).isFalse()
+    }
+
+    @Test
+    fun `should return false if password or confirmedPassword is empty`() {
+        val result = sut.validateRegistrationInput(
+            "Sunil",
+            "",
+            ""
+        )
+        assertThat(result).isFalse()
+    }
+
+    @Test
+    fun `should return false if confirmedPassword is not same as password`() {
+        val result = sut.validateRegistrationInput(
+            "Sunil",
+            "Password@123",
+            "Password"
+        )
+        assertThat(result).isFalse()
+    }
+
+    @Test
+    fun `should return false if password does not contain at least 2 digits`() {
+        val result = sut.validateRegistrationInput(
+            "Sunil",
+            "Password",
+            "Password"
+        )
+        assertThat(result).isFalse()
+    }
+
+    @After
+    fun tearDown() {
+        //no need to do anything here as Garbage Collector will clean up resourceComparer automatically
+        //but in case if there is DatabaseConection object that that needs to be closed here
+    }
+}