Migrate StyleSheet pure-logic Jest tests to Fantom (#57260)

Summary:
Pull Request resolved: #57260

Migrates the pure-logic StyleSheet unit tests from regular Jest (`-test.js`) to Fantom (`-itest.js`), so they run on Hermes inside the real React Native runtime, the same engine that runs this code in production.

Migrated files (all style-processing utilities that run on the client at runtime): `flattenStyle`, `processAspectRatio`, `processBackgroundPosition`, `processBackgroundRepeat`, `processBackgroundSize`, `processFilter`, `processFontVariant`, `processTransform`, `processTransformOrigin`, `setNormalizedColorAlpha`, `splitLayoutProps`.

Notable adaptations:
- `toThrowErrorMatchingSnapshot()` and `toThrowErrorMatchingInlineSnapshot()` are not available in Fantom, so they were replaced with `toThrow('<exact message>')`, preserving the exact error messages that were previously captured in snapshots.
- Removed the now-obsolete file snapshots for `processAspectRatio`, `processTransform`, and `processTransformOrigin`.
- `toMatchInlineSnapshot` (used by `splitLayoutProps`) is supported by Fantom and was kept unchanged.

Changelog: [Internal]

Reviewed By: sammy-SC

Differential Revision: D108759084

fbshipit-source-id: 42085f6f09286022655ea71b6a8e430cadf647a7

Author: rubennorte

packages/react-native/Libraries/StyleSheet/__tests__/__snapshots__/processAspectRatio-test.js.snap

@@ -8,7 +8,7 @@
  * @format
  */
 
-'use strict';
+import '@react-native/fantom/src/setUpDefaultReactNativeEnvironment';
 
 const flattenStyle = require('../flattenStyle').default;
 const StyleSheet = require('../StyleSheet').default;

packages/react-native/Libraries/StyleSheet/__tests__/__snapshots__/processTransform-test.js.snap

@@ -8,6 +8,7 @@
  * @format
  */
 
+import '@react-native/fantom/src/setUpDefaultReactNativeEnvironment';
 import processAspectRatio from '../processAspectRatio';
 
 describe('processAspectRatio', () => {
@@ -41,9 +42,15 @@ describe('processAspectRatio', () => {
   });
 
   it('should not accept invalid formats', () => {
-    expect(() => processAspectRatio('0a')).toThrowErrorMatchingSnapshot();
-    expect(() => processAspectRatio('1 / 1 1')).toThrowErrorMatchingSnapshot();
-    expect(() => processAspectRatio('auto 1/1')).toThrowErrorMatchingSnapshot();
+    expect(() => processAspectRatio('0a')).toThrow(
+      'aspectRatio must either be a number, a ratio string or `auto`. You passed: 0a',
+    );
+    expect(() => processAspectRatio('1 / 1 1')).toThrow(
+      'aspectRatio must either be a number, a ratio string or `auto`. You passed: 1 / 1 1',
+    );
+    expect(() => processAspectRatio('auto 1/1')).toThrow(
+      'aspectRatio must either be a number, a ratio string or `auto`. You passed: auto 1/1',
+    );
   });
 
   it('should ignore non string falsy types', () => {
@@ -57,8 +64,12 @@ describe('processAspectRatio', () => {
   it('should not accept non string truthy types', () => {
     const invalidThings = [() => {}, [1, 2, 3], {}];
     for (const thing of invalidThings) {
-      // $FlowExpectedError[incompatible-type]
-      expect(() => processAspectRatio(thing)).toThrowErrorMatchingSnapshot();
+      expect(() =>
+        // $FlowExpectedError[incompatible-type]
+        processAspectRatio(thing),
+      ).toThrow(
+        `aspectRatio must either be a number, a ratio string or \`auto\`. You passed: ${String(thing)}`,
+      );
     }
   });
 });

packages/react-native/Libraries/StyleSheet/__tests__/__snapshots__/processTransformOrigin-test.js.snap

@@ -8,8 +8,7 @@
  * @format
  */
 
-'use strict';
-
+import '@react-native/fantom/src/setUpDefaultReactNativeEnvironment';
 import processBackgroundPosition from '../processBackgroundPosition';
 
 describe('processBackgroundPosition', () => {

…tyleSheet/__tests__/flattenStyle-test.js …yleSheet/__tests__/flattenStyle-itest.jspackages/react-native/Libraries/StyleSheet/__tests__/flattenStyle-test.js renamed to packages/react-native/Libraries/StyleSheet/__tests__/flattenStyle-itest.js packages/react-native/Libraries/StyleSheet/__tests__/flattenStyle-test.js renamed to packages/react-native/Libraries/StyleSheet/__tests__/flattenStyle-itest.js

@@ -8,8 +8,7 @@
  * @format
  */
 
-'use strict';
-
+import '@react-native/fantom/src/setUpDefaultReactNativeEnvironment';
 import processBackgroundRepeat from '../processBackgroundRepeat';
 
 describe('processBackgroundRepeat', () => {

…eet/__tests__/processAspectRatio-test.js …et/__tests__/processAspectRatio-itest.jspackages/react-native/Libraries/StyleSheet/__tests__/processAspectRatio-test.js renamed to packages/react-native/Libraries/StyleSheet/__tests__/processAspectRatio-itest.js packages/react-native/Libraries/StyleSheet/__tests__/processAspectRatio-test.js renamed to packages/react-native/Libraries/StyleSheet/__tests__/processAspectRatio-itest.js

@@ -8,8 +8,7 @@
  * @format
  */
 
-'use strict';
-
+import '@react-native/fantom/src/setUpDefaultReactNativeEnvironment';
 import processBackgroundSize from '../processBackgroundSize';
 
 describe('processBackgroundSize', () => {

…ests__/processBackgroundPosition-test.js …sts__/processBackgroundPosition-itest.jspackages/react-native/Libraries/StyleSheet/__tests__/processBackgroundPosition-test.js renamed to packages/react-native/Libraries/StyleSheet/__tests__/processBackgroundPosition-itest.js packages/react-native/Libraries/StyleSheet/__tests__/processBackgroundPosition-test.js renamed to packages/react-native/Libraries/StyleSheet/__tests__/processBackgroundPosition-itest.js

@@ -10,6 +10,8 @@
 
 'use strict';
 
+import '@react-native/fantom/src/setUpDefaultReactNativeEnvironment';
+
 import type {FilterFunction} from '../StyleSheetTypes';
 
 import processColor from '../processColor';

…_tests__/processBackgroundRepeat-test.js …tests__/processBackgroundRepeat-itest.jspackages/react-native/Libraries/StyleSheet/__tests__/processBackgroundRepeat-test.js renamed to packages/react-native/Libraries/StyleSheet/__tests__/processBackgroundRepeat-itest.js packages/react-native/Libraries/StyleSheet/__tests__/processBackgroundRepeat-test.js renamed to packages/react-native/Libraries/StyleSheet/__tests__/processBackgroundRepeat-itest.js

@@ -8,7 +8,7 @@
  * @format
  */
 
-'use strict';
+import '@react-native/fantom/src/setUpDefaultReactNativeEnvironment';
 
 const processFontVariant = require('../processFontVariant').default;