Start adding tests

tests/GmailFilterTest.php

@@ -0,0 +1,24 @@
+<?php
+
+class GmailFilterTest extends \PHPUnit_Framework_TestCase
+{
+    public function testSingleFrom() {
+        $filters[] = GmailFilter::create()
+            ->from(['foo@example.com']);
+
+        // TODO: Does this need to be done each time?
+        $builder = (string) new GmailFilterBuilder($filters);
+
+        $this->assertContains('<apps:property name=\'from\' value=\'foo@example.com\'/>', $builder);
+    }
+
+    public function testMultipleFrom() {
+        $filters[] = GmailFilter::create()
+            ->from(['foo@example.com', 'bar@example.com']);
+
+        // TODO: Does this need to be done each time?
+        $builder = (string) new GmailFilterBuilder($filters);
+
+        $this->assertContains('<apps:property name=\'from\' value=\'foo@example.com OR bar@example.com\'/>', $builder);
+    }
+}