Add E2E Test for experimental_layoutConformance (facebook#42002)

Summary:
Pull Request resolved: facebook#42002

Adds an E2E test on top of the RNTester example for this (as a practice we should probably do this for new examples).

I didn't add unit tests for this originally, but probably should do that as well if it gets more interesting...

Changelog: [Internal]

Reviewed By: joevilches

Differential Revision: D51639134

fbshipit-source-id: 379d95dfc676252e10b7076e294ac5534c6f06bf

packages/rn-tester/js/examples/View/ViewExample.js

@@ -343,9 +343,11 @@ class FlexGapExample extends React.Component<$ReadOnly<{|testID?: ?string|}>> {
   }
 }
 
-function LayoutConformanceExample(): React.Node {
+function LayoutConformanceExample({
+  testID,
+}: $ReadOnly<{testID: ?string}>): React.Node {
   return (
-    <View style={{flexDirection: 'row', gap: 10}}>
+    <View style={{flexDirection: 'row', gap: 10}} testID={testID}>
       <View>
         <Text>Unset</Text>
         <LayoutConformanceBox />
@@ -367,8 +369,8 @@ function LayoutConformanceBox(): React.Node {
     <View
       style={{
         backgroundColor: 'blue',
-        width: 100,
-        height: 100,
+        width: 60,
+        height: 60,
         flexDirection: 'row',
         alignItems: 'center',
       }}>
@@ -378,7 +380,7 @@ function LayoutConformanceBox(): React.Node {
         }}>
         <View
           style={{
-            height: 50,
+            height: 30,
             backgroundColor: 'red',
             flexGrow: 1,
           }}