test: add unit tests for "InternalError"

src/core/utils/internal/devUtils.test.ts

@@ -0,0 +1,21 @@
+import { InternalError } from './devUtils'
+
+describe(InternalError, () => {
+  it('creates an InternalError instance', () => {
+    const error = new InternalError('Message')
+
+    expect(error.name).toBe('InternalError')
+    expect(error.message).toBe('Message')
+    expect(error.toString()).toBe('InternalError: Message')
+    expect(error.stack).toMatch(/\w+/)
+  })
+
+  it('passes the identity check', () => {
+    const error = new InternalError('Message')
+    expect(error instanceof InternalError).toBe(true)
+    expect(error instanceof Error).toBe(true)
+
+    const extraneousError = new Error('Message')
+    expect(extraneousError).not.toBeInstanceOf(InternalError)
+  })
+})

src/core/utils/internal/devUtils.ts

@@ -30,6 +30,15 @@ export const devUtils = {
   error,
 }
 
+/**
+ * Internal error instance.
+ * Used to differentiate the library errors that must be forwarded
+ * to the user from the unhandled exceptions. Use this if you don't
+ * wish for the error to be coerced to a 500 fallback response.
+ */
 export class InternalError extends Error {
-  //
+  constructor(message: string) {
+    super(message)
+    this.name = 'InternalError'
+  }
 }