[components] ktx: Add extension methods: View.isGone() / isVisible() / isInvisible().

Author: pocmo

android-components/components/support/ktx/src/main/java/mozilla/components/support/ktx/android/view/View.kt

@@ -42,6 +42,27 @@ val View.isLTR: Boolean
 fun View.dp(pixels: Int) = TypedValue.applyDimension(
     TypedValue.COMPLEX_UNIT_DIP, pixels.toFloat(), resources.displayMetrics).toInt()
 
+/**
+ * Returns true if this view's visibility is set to View.VISIBLE.
+ */
+fun View.isVisible(): Boolean {
+    return visibility == View.VISIBLE
+}
+
+/**
+ * Returns true if this view's visibility is set to View.GONE.
+ */
+fun View.isGone(): Boolean {
+    return visibility == View.GONE
+}
+
+/**
+ * Returns true if this view's visibility is set to View.INVISIBLE.
+ */
+fun View.isInvisible(): Boolean {
+    return visibility == View.INVISIBLE
+}
+
 /**
  * Tries to focus this view and show the soft input window for it.
  */

android-components/components/support/ktx/src/test/java/mozilla/components/support/ktx/android/view/ViewTest.kt

@@ -14,6 +14,7 @@ import org.robolectric.RobolectricTestRunner
 import org.robolectric.RuntimeEnvironment
 import org.robolectric.shadows.ShadowLooper
 import android.util.DisplayMetrics
+import android.view.View
 import org.junit.Assert.assertEquals
 import org.junit.Assert.assertNotEquals
 
@@ -43,4 +44,27 @@ class ViewTest {
             assertNotEquals(0, view.dp(i))
         }
     }
+
+    @Test
+    fun `visibility helper methods`() {
+        val view = TextView(RuntimeEnvironment.application)
+
+        view.visibility = View.GONE
+
+        assertTrue(view.isGone())
+        assertFalse(view.isVisible())
+        assertFalse(view.isInvisible())
+
+        view.visibility = View.VISIBLE
+
+        assertFalse(view.isGone())
+        assertTrue(view.isVisible())
+        assertFalse(view.isInvisible())
+
+        view.visibility = View.INVISIBLE
+
+        assertFalse(view.isGone())
+        assertFalse(view.isVisible())
+        assertTrue(view.isInvisible())
+    }
 }