core: Add new utility method to extract AnnotationProperties from Error instances

packages/core/__tests__/utils.test.ts

@@ -0,0 +1,26 @@
+import {toAnnotationProperties} from '../src/utils'
+
+describe('@actions/core/src/utils', () => {
+  describe('.toAnnotationProperties', () => {
+    it('extracts title only from Error instance without a parseable stack', () => {
+      const error = new TypeError('Test error')
+      error.stack = ''
+      expect(toAnnotationProperties(error)).toEqual({
+        title: 'TypeError',
+        file: undefined,
+        startLine: undefined,
+        startColumn: undefined
+      })
+    })
+
+    it('extracts AnnotationProperties from Error instance', () => {
+      const error = new ReferenceError('Test error')
+      expect(toAnnotationProperties(error)).toEqual({
+        title: 'ReferenceError',
+        file: expect.stringMatching(/utils\.test\.ts$/),
+        startLine: expect.any(Number),
+        startColumn: expect.any(Number)
+      })
+    })
+  })
+})