add new method and unit test

app/src/main/java/com/xianwei/codecoveragetestapp/CalculatorViewModel.kt

@@ -15,13 +15,12 @@ class CalculatorViewModel : ViewModel() {
         state.value = inputA - inputB
     }
 
-    fun onInputAUpdate(toString: String) {
-
+    fun onMultiplyClicked(inputA: Int, inputB: Int) {
+        state.value = inputA * inputB
     }
 
-    fun onInputBUpdate(toString: String) {
-
-
+    fun onDividerClicked(inputA: Int, inputB: Int) {
+        state.value = inputA / inputB
     }
 
 }

app/src/main/java/com/xianwei/codecoveragetestapp/MainActivity.kt

@@ -42,9 +42,17 @@ class MainActivity : AppCompatActivity() {
         }
 
         binding.multiply.setOnClickListener {
+            if (validInput()) {
+                viewModel.onMultiplyClicked(inputA, inputB)
+                binding.sign.text = "*"
+            }
         }
 
         binding.divider.setOnClickListener {
+            if (validInput()) {
+                viewModel.onDividerClicked(inputA, inputB)
+                binding.sign.text = "/"
+            }
         }
     }
 

app/src/test/java/com/xianwei/codecoveragetestapp/CalculatorViewModelTest.kt

@@ -1,18 +1,12 @@
 package com.xianwei.codecoveragetestapp
 
 import androidx.arch.core.executor.testing.InstantTaskExecutorRule
-import androidx.test.ext.junit.runners.AndroidJUnit4
-import org.junit.Assert
 import org.junit.Assert.assertEquals
-
 import org.junit.Before
 import org.junit.Rule
 import org.junit.Test
 import org.junit.runner.RunWith
 import org.junit.runners.JUnit4
-import org.mockito.Mock
-import org.mockito.Mockito
-import org.mockito.MockitoAnnotations
 
 @RunWith(JUnit4::class)
 class CalculatorViewModelTest {
@@ -32,4 +26,22 @@ class CalculatorViewModelTest {
         testViewModel.onPlusClicked(9, 2)
         assertEquals(11, testViewModel.state.value)
     }
+
+    @Test
+    fun test_on_minus_click_method() {
+        testViewModel.onMinusClicked(9, 2)
+        assertEquals(7, testViewModel.state.value)
+    }
+
+    @Test
+    fun test_on_multiply_click_method() {
+        testViewModel.onMultiplyClicked(9, 2)
+        assertEquals(18, testViewModel.state.value)
+    }
+
+    @Test
+    fun test_on_divider_click_method() {
+        testViewModel.onDividerClicked(9, 3)
+        assertEquals(3, testViewModel.state.value)
+    }
 }