Allow 0 (zero) and "" (empty string) to be returned as string. (#39)

* Allow 0 (zero) and "" (empty string) to be returned as a string.

* Add unit tests for Record

Author: jsjacob

src/record.js

@@ -38,8 +38,9 @@ class Record {
 			index = this._header.indexOf(key);
 		}
 
-		if (this._values[index]) {
-			return this._values[index].toString();
+		let value = this._values[index];
+		if (value !== undefined && value !== null) {
+			return value.toString();
 		}
 
 		return null;

test/recordTest.js

@@ -0,0 +1,57 @@
+"use strict";
+const assert = require("assert"),
+	Record = require("../src/record");
+
+describe("Record Test", () => {
+	describe('getString()', () => {
+		const recordUnderTest = new Record([
+			"key",
+			"keyForEmptyString",
+			"keyForZero",
+			"keyForTwelve",
+			"keyForNullValue"
+		], [
+			"valueForKey",
+			"",
+			0,
+			12,
+			null
+		]);
+
+		context('key is not given', () => {
+			it('returns null', () => {
+				assert.equal(recordUnderTest.getString(), null);
+			});
+		});
+		context('key is undefined', () => {
+			it('returns null', () => {
+				assert.equal(recordUnderTest.getString(undefined), null);
+			});
+		});
+		context('value is empty string', () => {
+			it('returns empty string', () => {
+				assert.equal(recordUnderTest.getString('keyForEmptyString'), '');
+			});
+		});
+		context('value is zero (0)', () => {
+			it('returns zero (0) as string', () => {
+				assert.equal(recordUnderTest.getString('keyForZero'), '0');
+			});
+		});
+		context('value is non-zero integer', () => {
+			it('returns non-zero integer as string', () => {
+				assert.equal(recordUnderTest.getString('keyForTwelve'), '12');
+			});
+		});
+		context('value is string', () => {
+			it('returns value', () => {
+				assert.equal(recordUnderTest.getString('key'), 'valueForKey');
+			});
+		});
+		context('value is null', () => {
+			it('returns null', () => {
+				assert.equal(recordUnderTest.getString('keyForNullValue'), null);
+			});
+		});
+	});
+});