Improved support for exponent and square root in input processing

app/src/main/java/com/sadellie/unitto/screens/main/MainViewModel.kt

@@ -40,6 +40,7 @@ import com.sadellie.unitto.data.KEY_8
 import com.sadellie.unitto.data.KEY_9
 import com.sadellie.unitto.data.KEY_DIVIDE
 import com.sadellie.unitto.data.KEY_DOT
+import com.sadellie.unitto.data.KEY_EXPONENT
 import com.sadellie.unitto.data.KEY_LEFT_BRACKET
 import com.sadellie.unitto.data.KEY_MINUS
 import com.sadellie.unitto.data.KEY_MULTIPLY
@@ -309,16 +310,18 @@ class MainViewModel @Inject constructor(
         _deleteButtonEnabled.update { true }
 
         when (symbolToAdd) {
-            KEY_PLUS, KEY_DIVIDE, KEY_MULTIPLY -> {
+            KEY_PLUS, KEY_DIVIDE, KEY_MULTIPLY, KEY_EXPONENT -> {
                 when {
                     // Don't need expressions that start with zero
-                    (inputValue.value == KEY_0) or (inputValue.value == KEY_MINUS) -> {}
+                    (inputValue.value == KEY_0) -> {}
+                    (inputValue.value == KEY_MINUS) -> {}
+                    (lastSymbol == KEY_SQRT) -> {}
                     /**
                      * For situations like "50+-", when user clicks "/" we delete "-" so it becomes
                      * "50+". We don't add "/' here. User will click "/" second time and the input
                      * will be "50/".
                      */
-                    (lastSecondSymbol in OPERATORS) and (lastSymbol == KEY_MINUS)-> {
+                    (lastSecondSymbol in OPERATORS) and (lastSymbol == KEY_MINUS) -> {
                         deleteDigit()
                     }
                     // Don't allow multiple operators near each other

app/src/test/java/com/sadellie/unitto/screens/MainViewModelTest.kt

@@ -98,10 +98,11 @@ class MainViewModelTest {
          */
         `test 0`()
         `test digits from 1 to 9`()
-        `test plus, divide and multiply operators`()
+        `test plus, divide, multiply and exponent operators`()
         `test dot`()
         `test minus`()
         `test brackets`()
+        `test square root`()
 
         Dispatchers.resetMain()
     }
@@ -184,7 +185,7 @@ class MainViewModelTest {
         viewModel.clearInput()
     }
 
-    private fun `test plus, divide and multiply operators`() {
+    private fun `test plus, divide, multiply and exponent operators`() {
         // 0 | +++ | 0
         viewModel.processInput(KEY_PLUS)
         assertEquals("0", viewModel.inputValue.value)
@@ -222,6 +223,24 @@ class MainViewModelTest {
         assertEquals("1+", viewModel.inputValue.value)
         assertEquals("1+", viewModel.mainFlow.value.inputValue)
         viewModel.clearInput()
+
+        // 0 | ^^^ | 0
+        viewModel.processInput(KEY_EXPONENT)
+        viewModel.processInput(KEY_EXPONENT)
+        viewModel.processInput(KEY_EXPONENT)
+        assertEquals("0", viewModel.inputValue.value)
+        assertEquals("0", viewModel.mainFlow.value.inputValue)
+        viewModel.clearInput()
+
+        // 12 | ^^^ | 12^
+        viewModel.processInput(KEY_1)
+        viewModel.processInput(KEY_2)
+        viewModel.processInput(KEY_EXPONENT)
+        viewModel.processInput(KEY_EXPONENT)
+        viewModel.processInput(KEY_EXPONENT)
+        assertEquals("12^", viewModel.inputValue.value)
+        assertEquals("12^", viewModel.mainFlow.value.inputValue)
+        viewModel.clearInput()
     }
 
     private fun `test dot`() {
@@ -303,6 +322,26 @@ class MainViewModelTest {
         assertEquals("√-", viewModel.inputValue.value)
         assertEquals("√–", viewModel.mainFlow.value.inputValue)
         viewModel.clearInput()
+
+        // √ | /// | √
+        viewModel.processInput(KEY_SQRT)
+        viewModel.processInput(KEY_DIVIDE)
+        viewModel.processInput(KEY_DIVIDE)
+        viewModel.processInput(KEY_DIVIDE)
+        assertEquals("√", viewModel.inputValue.value)
+        assertEquals("√", viewModel.mainFlow.value.inputValue)
+        viewModel.clearInput()
+
+        // 12^- | --- | 12^-
+        viewModel.processInput(KEY_1)
+        viewModel.processInput(KEY_2)
+        viewModel.processInput(KEY_EXPONENT)
+        viewModel.processInput(KEY_MINUS)
+        viewModel.processInput(KEY_MINUS)
+        viewModel.processInput(KEY_MINUS)
+        assertEquals("12^-", viewModel.inputValue.value)
+        assertEquals("12^–", viewModel.mainFlow.value.inputValue)
+        viewModel.clearInput()
     }
 
     private fun `test brackets`() {
@@ -330,6 +369,17 @@ class MainViewModelTest {
         viewModel.processInput(KEY_RIGHT_BRACKET)
         assertEquals("√(10+2)", viewModel.inputValue.value)
         assertEquals("√(10+2)", viewModel.mainFlow.value.inputValue)
+        viewModel.clearInput()
+    }
+
+    private fun `test square root`() {
+        // 0 | √√√ | √√√
+        viewModel.processInput(KEY_SQRT)
+        viewModel.processInput(KEY_SQRT)
+        viewModel.processInput(KEY_SQRT)
+        assertEquals("√√√", viewModel.inputValue.value)
+        assertEquals("√√√", viewModel.mainFlow.value.inputValue)
+        viewModel.clearInput()
     }
 
     @Test