ModelError now accepts a previous error

lib/model-error.js

@@ -12,10 +12,16 @@ class ModelError extends Error {
 	}
 
 	constructor(err, code) {
-		super(err);
-		this.message = err.message || err;
+
+		const message = err.message || err;
+
+		super(message);
+		this.message = message;
 		this.code = code;
 		this.name = 'ModelError';
+
+		if(err instanceof Error)
+			this.previousError = err;
 	}
 }
 

tests/model-error.js

@@ -0,0 +1,28 @@
+'use strict';
+
+const assert = require('assert');
+
+const ModelError = require('../lib/model-error');
+
+describe('Api Session Error', () => {
+
+	it('Should accept a message error and a code', () => {
+		const error = new ModelError('Some error', ModelError.codes.DATABASE_CONFIG_NOT_FOUND);
+
+		assert.strictEqual(error.message, 'Some error');
+		assert.strictEqual(error.code, ModelError.codes.DATABASE_CONFIG_NOT_FOUND);
+		assert.strictEqual(error.name, 'ModelError');
+	});
+
+	it('Should accept an error instance and a code', () => {
+
+		const previousError = new Error('Some error');
+
+		const error = new ModelError(previousError, ModelError.codes.DATABASE_CONFIG_NOT_FOUND);
+
+		assert.strictEqual(error.message, 'Some error');
+		assert.strictEqual(error.code, ModelError.codes.DATABASE_CONFIG_NOT_FOUND);
+		assert.strictEqual(error.name, 'ModelError');
+		assert.strictEqual(error.previousError, previousError);
+	});
+});