fix(sdk/testing): _skyTestingCheckVisibility overwrites pass across multiple rules and may throw on null element

[coderabbitai]

Summary

In libs/sdk/testing/private/src/utility/check-visibility.ts, the _skyTestingCheckVisibility function has two related bugs that were carried over from the prior Jasmine toBeVisible matcher implementation.

Bug 1 – Later enabled rules can overwrite an earlier failure

Each enabled rule independently assigns pass rather than ANDing with the accumulated result. For example, with both checkCssDisplay and checkCssVisibility enabled, an element with display: none (which correctly sets pass = false) can have that result overwritten by a subsequent visibility: visible check (which sets pass = true), yielding an incorrect visible result.

Bug 2 – Unsafe access on null/undefined element

When checkExists is false (the default) and a null or undefined value is passed, the function proceeds to call window.getComputedStyle(el) and potentially el.getBoundingClientRect(), which will throw instead of returning false.

Suggested fix

 export function _skyTestingCheckVisibility(
-  el: Element,
+  el: Element | null | undefined,
   options?: _SkyTestingCheckVisibilityOptions,
 ): boolean {
   const settings = { ...DEFAULTS, ...options };

+  if (!el) {
+    return false;
+  }
+
   let pass = true;

-  if (settings.checkExists) {
-    pass = !!el;
-  }
-
   if (pass) {
     const computedStyle = window.getComputedStyle(el);

     if (settings.checkCssDisplay) {
-      pass = computedStyle.display !== 'none';
+      pass = pass && computedStyle.display !== 'none';
     }

     if (settings.checkCssVisibility) {
-      pass = computedStyle.visibility !== 'hidden';
+      pass = pass && computedStyle.visibility !== 'hidden';
     }

     if (settings.checkDimensions) {
       const box = el.getBoundingClientRect();
-      pass = box.width > 0 && box.height > 0;
+      pass = pass && box.width > 0 && box.height > 0;
     }
   }

A regression test with both CSS checks simultaneously enabled would also help lock this down.

Context

• Identified during review of PR feat(sdk/testing): duplicate jasmine matchers for vitest #4385: feat(sdk/testing): duplicate jasmine matchers for vitest #4385 (comment)
• Requested by @Blackbaud-SteveBrush

AB#3959363