tests: FocusedInputHolder (Android) (#370)

## 📜 Description

Added tests to `FocusedInputHolder`. Refactored code, reduced
duplications, aligned to JS-based namings.

## 💡 Motivation and Context

I decided to fully cover a new functionality with unit tests. The
`ViewHierarchyTraversal` was already covered, so I decided to cover
other classes. The next one `FocusedInputHolder`. This is a very simple
class, so it contains two unit tests:
- check that weak references implemented correctly;
- check that `focus` actually calls expected methods.

Along with that I did some refactoring: reduced code fragmentation,
reduced code duplication, aligned API to look similar to RN JS API (and
hide internals).

## 📢 Changelog

### iOS

- use `focus` instead of `requestFocus`;
- `FocusedInputHolder.shared.requestFocus()` ->
`FocusedInputHolder.shared.focus()`;

### Android

- added `FocusedInputHolderTests`
- added `focus` extension to avoid code duplication;
- use `focus` extension instead of `requestFocus`/`requestFocusFromJS`;
- `FocusedInputHolder.requestFocus()` -> `FocusedInputHolder.focus()`;
- `FocusedInputHolder` works with plain `EditText` (i. e. no
react-specific code);
- added `get` to `FocusedInputHolder`;

## 🤔 How Has This Been Tested?

Tested via CI.

## 📝 Checklist

- [x] CI successfully passed
- [x] I added new mocks and corresponding unit-tests if library API was
changed

android/src/main/java/com/reactnativekeyboardcontroller/extensions/EditText.kt

@@ -86,3 +86,11 @@ val EditText.parentScrollViewTarget: Int
     // ScrollView was not found
     return -1
   }
+
+fun EditText?.focus() {
+  if (this is ReactEditText) {
+    this.requestFocusFromJS()
+  } else {
+    this?.requestFocus()
+  }
+}

android/src/main/java/com/reactnativekeyboardcontroller/modules/KeyboardControllerModuleImpl.kt

@@ -32,7 +32,7 @@ class KeyboardControllerModuleImpl(private val mReactContext: ReactApplicationCo
 
   fun setFocusTo(direction: String) {
     if (direction == "current") {
-      return FocusedInputHolder.requestFocus()
+      return FocusedInputHolder.focus()
     }
 
     val activity = mReactContext.currentActivity

android/src/main/java/com/reactnativekeyboardcontroller/traversal/FocusedInputHolder.kt

@@ -1,16 +1,21 @@
 package com.reactnativekeyboardcontroller.traversal
 
-import com.facebook.react.views.textinput.ReactEditText
+import android.widget.EditText
+import com.reactnativekeyboardcontroller.extensions.focus
 import java.lang.ref.WeakReference
 
 object FocusedInputHolder {
-  private var input: WeakReference<ReactEditText?>? = null
+  private var input: WeakReference<EditText?>? = null
 
-  fun set(textInput: ReactEditText) {
+  fun set(textInput: EditText) {
     input = WeakReference(textInput)
   }
 
-  fun requestFocus() {
-    input?.get()?.requestFocusFromJS()
+  fun get(): EditText? {
+    return input?.get()
+  }
+
+  fun focus() {
+    input?.get()?.focus()
   }
 }

android/src/main/java/com/reactnativekeyboardcontroller/traversal/ViewHierarchyNavigator.kt

@@ -4,18 +4,14 @@ import android.view.View
 import android.view.ViewGroup
 import android.widget.EditText
 import com.facebook.react.bridge.UiThreadUtil
-import com.facebook.react.views.textinput.ReactEditText
+import com.reactnativekeyboardcontroller.extensions.focus
 
 object ViewHierarchyNavigator {
   fun setFocusTo(direction: String, view: View) {
     val input = if (direction == "next") findNextEditText(view) else findPreviousEditText(view)
 
     UiThreadUtil.runOnUiThread {
-      if (input is ReactEditText) {
-        input.requestFocusFromJS()
-      } else {
-        input?.requestFocus()
-      }
+      input.focus()
     }
   }
 

android/src/test/java/com/reactnativekeyboardcontroller/traversal/FocusedInputHolderTest.kt

@@ -0,0 +1,45 @@
+package com.reactnativekeyboardcontroller.traversal
+
+import android.content.Context
+import android.widget.EditText
+import androidx.test.core.app.ApplicationProvider
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertNull
+import org.junit.Assert.assertTrue
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.robolectric.RobolectricTestRunner
+
+@RunWith(RobolectricTestRunner::class)
+class FocusedInputHolderTest {
+  @Test
+  fun `FocusedInputHolder should hold a weak reference`() {
+    val context = ApplicationProvider.getApplicationContext<Context>()
+    var input: EditText? = EditText(context)
+
+    FocusedInputHolder.set(input as EditText)
+
+    assertEquals(FocusedInputHolder.get(), input)
+
+    input = null
+
+    @Suppress("detekt:ExplicitGarbageCollectionCall")
+    System.gc()
+
+    assertNull(FocusedInputHolder.get())
+  }
+
+  @Test
+  fun `focus() should request focus on expected field`() {
+    val context = ApplicationProvider.getApplicationContext<Context>()
+    val input = EditText(context)
+
+    assertFalse(input.hasFocus())
+
+    FocusedInputHolder.set(input)
+    FocusedInputHolder.focus()
+
+    assertTrue(input.hasFocus())
+  }
+}

android/src/test/java/com/reactnativekeyboardcontroller/traversal/ViewHierarchyNavigatorTest.kt

@@ -4,6 +4,7 @@ import android.content.Context
 import android.widget.EditText
 import android.widget.LinearLayout
 import androidx.test.core.app.ApplicationProvider
+import com.reactnativekeyboardcontroller.extensions.focus
 import org.junit.Assert.assertTrue
 import org.junit.Before
 import org.junit.Test
@@ -78,7 +79,7 @@ class ViewHierarchyNavigatorTest {
 
   @Test
   fun `setFocusTo to 'next' should set focus to next field`() {
-    editText1.requestFocus()
+    editText1.focus()
 
     ViewHierarchyNavigator.setFocusTo("next", editText1)
 
@@ -89,7 +90,7 @@ class ViewHierarchyNavigatorTest {
 
   @Test
   fun `setFocusTo to 'prev' should set focus to previous field`() {
-    editText2.requestFocus()
+    editText2.focus()
 
     ViewHierarchyNavigator.setFocusTo("prev", editText2)
 
@@ -100,7 +101,7 @@ class ViewHierarchyNavigatorTest {
 
   @Test
   fun `setFocusTo to 'next' should skip non-editable fields`() {
-    editText2.requestFocus()
+    editText2.focus()
 
     ViewHierarchyNavigator.setFocusTo("next", editText2)
 
@@ -111,7 +112,7 @@ class ViewHierarchyNavigatorTest {
 
   @Test
   fun `setFocusTo to 'prev' should skip non-editable fields`() {
-    editText5.requestFocus()
+    editText5.focus()
 
     ViewHierarchyNavigator.setFocusTo("prev", editText5)
 
@@ -122,7 +123,7 @@ class ViewHierarchyNavigatorTest {
 
   @Test
   fun `setFocusTo to 'next' should set focus relatively to current group`() {
-    editText5.requestFocus()
+    editText5.focus()
 
     ViewHierarchyNavigator.setFocusTo("next", editText5)
 
@@ -133,7 +134,7 @@ class ViewHierarchyNavigatorTest {
 
   @Test
   fun `setFocusTo to 'prev' should set focus relatively to current group`() {
-    editText7.requestFocus()
+    editText7.focus()
 
     ViewHierarchyNavigator.setFocusTo("prev", editText7)
 
@@ -144,7 +145,7 @@ class ViewHierarchyNavigatorTest {
 
   @Test
   fun `setFocusTo to 'next' should correctly exit from current group`() {
-    editText7.requestFocus()
+    editText7.focus()
 
     ViewHierarchyNavigator.setFocusTo("next", editText7)
 
@@ -155,7 +156,7 @@ class ViewHierarchyNavigatorTest {
 
   @Test
   fun `setFocusTo to 'prev' should set focus to last element in group`() {
-    editText8.requestFocus()
+    editText8.focus()
 
     ViewHierarchyNavigator.setFocusTo("prev", editText8)
 
@@ -166,7 +167,7 @@ class ViewHierarchyNavigatorTest {
 
   @Test
   fun `setFocusTo to 'next' should do nothing if it's last element`() {
-    editText13.requestFocus()
+    editText13.focus()
 
     ViewHierarchyNavigator.setFocusTo("next", editText13)
 
@@ -177,7 +178,7 @@ class ViewHierarchyNavigatorTest {
 
   @Test
   fun `setFocusTo to 'prev' should do nothing if it's first element`() {
-    editText1.requestFocus()
+    editText1.focus()
 
     ViewHierarchyNavigator.setFocusTo("prev", editText1)
 

ios/traversal/FocusedInputHolder.swift

@@ -19,14 +19,14 @@ class FocusedInputHolder {
     currentFocusedInput = input
   }
 
-  // Requests focus for the currentFocusedInput if it's set
-  func requestFocus() {
-    currentFocusedInput?.requestFocus()
-  }
-
   func get() -> TextInput? {
     return currentFocusedInput
   }
 
+  // Requests focus for the currentFocusedInput if it's set
+  func focus() {
+    currentFocusedInput?.focus()
+  }
+
   private init() {}
 }

ios/traversal/TextInput.swift

@@ -10,17 +10,17 @@ import Foundation
 import UIKit
 
 public protocol TextInput: AnyObject {
-  func requestFocus()
+  func focus()
 }
 
 extension UITextField: TextInput {
-  public func requestFocus() {
+  public func focus() {
     becomeFirstResponder()
   }
 }
 
 extension UITextView: TextInput {
-  public func requestFocus() {
+  public func focus() {
     becomeFirstResponder()
   }
 }

ios/traversal/ViewHierarchyNavigator.swift

@@ -14,15 +14,15 @@ public class ViewHierarchyNavigator: NSObject {
   @objc public static func setFocusTo(direction: String) {
     DispatchQueue.main.async {
       if direction == "current" {
-        FocusedInputHolder.shared.requestFocus()
+        FocusedInputHolder.shared.focus()
         return
       }
 
       let input = (FocusedInputHolder.shared.get() as? UIView) ?? (UIResponder.current as? UIView) ?? nil
       guard let view = input else { return }
 
       let textField = findTextInputInDirection(currentFocus: view, direction: direction)
-      textField?.requestFocus()
+      textField?.focus()
     }
   }