fix(compiler-core): Add switch-case test

Author: wngtk

packages/compiler-core/__tests__/transforms/transformExpressions.spec.ts

@@ -716,4 +716,51 @@ describe('compiler: expression transform', () => {
       })
     })
   })
+
+  // Test for switch case variable declarations bug fix
+  describe('switch case variable declarations', () => {
+    test('should handle const declarations in switch case without braces', () => {
+      const node = parseWithExpressionTransform(
+        `{{ (() => { switch (1) { case 1: const foo = "bar"; return \`\${foo}\`; } })() }}`,
+      ) as InterpolationNode
+
+      // The variable 'foo' should be recognized as local and not prefixed with _ctx
+      expect(node.content).toMatchObject({
+        type: NodeTypes.COMPOUND_EXPRESSION,
+      })
+
+      // Check that 'foo' is not prefixed with '_ctx.'
+      const children = (node.content as any).children
+      const codeStr = children
+        .map((c: any) => (typeof c === 'string' ? c : c.content))
+        .join('')
+      expect(codeStr).not.toContain('_ctx.foo')
+      expect(codeStr).toContain('foo')
+    })
+
+    test('should handle const declarations in switch case with braces (existing behavior)', () => {
+      const node = parseWithExpressionTransform(
+        `{{ (() => {
+          switch (true) {
+            case true: {
+              const foo = "bar";
+              return \`\${foo}\`;
+            }
+          }
+        })() }}`,
+      ) as InterpolationNode
+
+      // This should work correctly even before our fix
+      expect(node.content).toMatchObject({
+        type: NodeTypes.COMPOUND_EXPRESSION,
+      })
+
+      const children = (node.content as any).children
+      const codeStr = children
+        .map((c: any) => (typeof c === 'string' ? c : c.content))
+        .join('')
+      expect(codeStr).not.toContain('_ctx.foo')
+      expect(codeStr).toContain('foo')
+    })
+  })
 })