Add unit test for TextLayoutManager desired width optimization

packages/react-native/ReactAndroid/src/test/java/com/facebook/react/views/text/TextLayoutManagerDesiredWidthTest.kt

@@ -0,0 +1,106 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+package com.facebook.react.views.text
+
+import android.annotation.SuppressLint
+import android.text.BoringLayout
+import android.text.Layout
+import android.text.SpannableString
+import android.text.TextPaint
+import com.facebook.yoga.YogaMeasureMode
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.mockito.MockedStatic
+import org.mockito.Mockito.CALLS_REAL_METHODS
+import org.mockito.Mockito.mockStatic
+import org.mockito.Mockito.never
+import org.mockito.Mockito.times
+import org.mockito.kotlin.any
+import org.mockito.verification.VerificationMode
+import org.robolectric.RobolectricTestRunner
+import org.robolectric.annotation.Config
+
+@RunWith(RobolectricTestRunner::class)
+@SuppressLint("NewApi")
+@Config(sdk = [35])
+class TextLayoutManagerDesiredWidthTest {
+
+  @Test
+  fun `EXACTLY mode does not measure the desired width`() {
+    mockStatic(Layout::class.java, CALLS_REAL_METHODS).use { layoutStatic ->
+      val layout = createLayout(YogaMeasureMode.EXACTLY, boring = null)
+
+      layoutStatic.verifyDesiredWidthCalls(never())
+      assertThat(layout.width).isEqualTo(LAYOUT_WIDTH.toInt())
+    }
+  }
+
+  @Test
+  fun `AT_MOST mode does not measure the desired width when boring text does not fit`() {
+    mockStatic(Layout::class.java, CALLS_REAL_METHODS).use { layoutStatic ->
+      val layout = createLayout(YogaMeasureMode.AT_MOST, boring = boringMetrics(width = 500))
+
+      layoutStatic.verifyDesiredWidthCalls(never())
+      assertThat(layout.width).isEqualTo(LAYOUT_WIDTH.toInt())
+    }
+  }
+
+  @Test
+  fun `AT_MOST mode measures the desired width when the text is not boring`() {
+    mockStatic(Layout::class.java, CALLS_REAL_METHODS).use { layoutStatic ->
+      val layout = createLayout(YogaMeasureMode.AT_MOST, boring = null)
+
+      layoutStatic.verifyDesiredWidthCalls(times(1))
+      assertThat(layout.width).isLessThanOrEqualTo(LAYOUT_WIDTH.toInt())
+    }
+  }
+
+  @Test
+  fun `UNDEFINED mode measures the desired width when the text is not boring`() {
+    mockStatic(Layout::class.java, CALLS_REAL_METHODS).use { layoutStatic ->
+      val layout = createLayout(YogaMeasureMode.UNDEFINED, boring = null)
+
+      layoutStatic.verifyDesiredWidthCalls(times(1))
+      assertThat(layout.lineCount).isEqualTo(1)
+    }
+  }
+
+  private fun MockedStatic<Layout>.verifyDesiredWidthCalls(mode: VerificationMode) {
+    verify({ Layout.getDesiredWidth(any<CharSequence>(), any<TextPaint>()) }, mode)
+  }
+
+  private fun boringMetrics(width: Int): BoringLayout.Metrics =
+      BoringLayout.Metrics().apply {
+        this.width = width
+        ascent = -20
+        descent = 5
+        top = -22
+        bottom = 6
+      }
+
+  private fun createLayout(widthMode: YogaMeasureMode, boring: BoringLayout.Metrics?): Layout =
+      TextLayoutManager.createLayout(
+          text = SpannableString("hello world"),
+          boring = boring,
+          width = LAYOUT_WIDTH,
+          widthYogaMeasureMode = widthMode,
+          includeFontPadding = false,
+          textBreakStrategy = Layout.BREAK_STRATEGY_HIGH_QUALITY,
+          hyphenationFrequency = Layout.HYPHENATION_FREQUENCY_NONE,
+          alignment = Layout.Alignment.ALIGN_NORMAL,
+          justificationMode = 0,
+          ellipsizeMode = null,
+          maxNumberOfLines = 2,
+          paint = TextPaint(TextPaint.ANTI_ALIAS_FLAG).apply { textSize = 26f },
+      )
+
+  private companion object {
+    const val LAYOUT_WIDTH = 200f
+  }
+}