Add missing test cases for processBoxShadow parseLength edge cases (facebook#55715)

Summary:

Changelog: [Internal]

Add tests covering previously untested branches in the parseLength regex and processBoxShadow logic

Reviewed By: jorge-cab

Differential Revision: D94087958

Author: sammy-SC

packages/react-native/Libraries/StyleSheet/__tests__/processBoxShadow-test.js

@@ -213,10 +213,36 @@ describe('processBoxShadow', () => {
     expect(processBoxShadow('red 10foo 5px 2px 3px,')).toEqual([]);
   });
 
+  it('should fail to parse decimal number with invalid unit', () => {
+    expect(processBoxShadow('1.5dog 2px')).toEqual([]);
+  });
+
   it('should fail to parse invalid argument', () => {
     expect(processBoxShadow('red asf 5px 2px 3px')).toEqual([]);
   });
 
+  it('should parse string with leading dot decimal', () => {
+    expect(processBoxShadow('.5px 2px')).toEqual([
+      {
+        offsetX: 0.5,
+        offsetY: 2,
+      },
+    ]);
+  });
+
+  it('should parse string with explicit positive sign', () => {
+    expect(processBoxShadow('+5px 2px')).toEqual([
+      {
+        offsetX: 5,
+        offsetY: 2,
+      },
+    ]);
+  });
+
+  it('should fail to parse trailing dot without fractional digits', () => {
+    expect(processBoxShadow('10.px 5px')).toEqual([]);
+  });
+
   it('should fail to parse negative blur', () => {
     expect(processBoxShadow('red 5px 2px -3px')).toEqual([]);
   });
@@ -306,4 +332,15 @@ describe('processBoxShadow', () => {
       ]),
     ).toEqual([]);
   });
+
+  it('should fail to parse object with unitless non-zero string', () => {
+    expect(
+      processBoxShadow([
+        {
+          offsetX: '5',
+          offsetY: 10,
+        },
+      ]),
+    ).toEqual([]);
+  });
 });