Adds unit tests for UpwardServerError.js (#868)

packages/upward-js/lib/UpwardServerError.js

@@ -4,7 +4,10 @@ class UpwardServerError extends Error {
     }
     constructor(originalError, message) {
         super(originalError);
-        this.message += ' -- ' + message;
+
+        if (message) {
+            this.message += ' -- ' + message;
+        }
     }
 }
 

packages/upward-js/lib/__tests__/UpwardServerError.test.js

@@ -0,0 +1,58 @@
+import UpwardServerError from '../UpwardServerError';
+
+const MOCK_ERROR_MESSAGE = 'Unit Test';
+const MOCK_ERROR = new Error(MOCK_ERROR_MESSAGE);
+const MOCK_ADDITIONAL_MESSAGE = 'Additional Unit Test Message';
+
+describe('class', () => {
+    test('it is of type Error', () => {
+        const result = new UpwardServerError(
+            MOCK_ERROR,
+            MOCK_ADDITIONAL_MESSAGE
+        );
+
+        expect(result).toBeInstanceOf(Error);
+    });
+
+    test('it can accept an error object as its first argument', () => {
+        const result = new UpwardServerError(MOCK_ERROR);
+
+        expect(result).toBeInstanceOf(Error);
+    });
+
+    test('it can accept a string as its first argument', () => {
+        const result = new UpwardServerError(MOCK_ERROR_MESSAGE);
+
+        expect(result).toBeInstanceOf(Error);
+    });
+});
+
+describe('name', () => {
+    test('it equals "UpwardServerError"', () => {
+        const result = new UpwardServerError(
+            MOCK_ERROR,
+            MOCK_ADDITIONAL_MESSAGE
+        );
+
+        expect(result.name).toBe('UpwardServerError');
+    });
+});
+
+describe('message', () => {
+    test('it appends a custom message to the original error', () => {
+        const result = new UpwardServerError(
+            MOCK_ERROR,
+            MOCK_ADDITIONAL_MESSAGE
+        );
+
+        expect(result.message).toEqual(
+            `Error: ${MOCK_ERROR_MESSAGE} -- ${MOCK_ADDITIONAL_MESSAGE}`
+        );
+    });
+
+    test('it does not append a custom message if one is not present', () => {
+        const result = new UpwardServerError(MOCK_ERROR);
+
+        expect(result.message).toEqual(`Error: ${MOCK_ERROR_MESSAGE}`);
+    });
+});