Add basic email logger test

tests/unit-tests/log/log-handler-email.php

@@ -0,0 +1,47 @@
+<?php
+
+/**
+ * Class WC_Tests_Log_Handler_Email
+ * @package WooCommerce\Tests\Log
+ * @since 2.8
+ */
+
+if ( ! class_exists( 'WC_Log_Handler_Email' ) ) {
+	include_once(
+		dirname( dirname( dirname( dirname( __FILE__ ) ) ) )
+		. '/includes/log-handlers/class-wc-log-handler-email.php'
+	);
+}
+
+class WC_Tests_Log_Handler_Email extends WC_Unit_Test_Case {
+
+	function setUp() {
+		parent::setUp();
+		reset_phpmailer_instance();
+	}
+
+	function tearDown() {
+		reset_phpmailer_instance();
+		parent::tearDown();
+	}
+
+	/**
+	 * Test handle writes to database correctly.
+	 *
+	 * @since 2.8
+	 */
+	public function test_handle() {
+		$handler = new WC_Log_Handler_Email( array( 'threshold' => 'debug' ) );
+		$time = time();
+
+		$handler->handle( $time, 'debug', 'msg_debug', array() );
+
+		$mailer = tests_retrieve_phpmailer_instance();
+
+		$this->assertEquals(
+			'You have recieved the following WooCommerce log message:' . PHP_EOL . PHP_EOL . date( 'c', $time ) . ' DEBUG msg_debug' . PHP_EOL,
+			$mailer->get_sent()->body
+		);
+	}
+
+}