From 90aaaeb3a39d83adf1fa79d5427f392fbf56d322 Mon Sep 17 00:00:00 2001
From: Mike Gerwitz <mike@mikegerwitz.com>
Date: Wed, 29 Jun 2011 21:22:57 -0400
Subject: [PATCH] Added 'log' warning handler

---
 lib/warn.js                |  28 +++++++++
 test/test-warn-handlers.js | 118 +++++++++++++++++++++++++++++++++++++
 2 files changed, 146 insertions(+)
 create mode 100644 test/test-warn-handlers.js

diff --git a/lib/warn.js b/lib/warn.js
index b9983f8..03409f2 100644
--- a/lib/warn.js
+++ b/lib/warn.js
@@ -65,3 +65,31 @@ Warning.prototype.getError = function()
     return this._error;
 };
 
+
+/**
+ * Core warning handlers
+ * @type {Object}
+ */
+exports.handlers = {
+    /**
+     * Logs message to console
+     *
+     * Will attempt to log using console.warn(), falling back to console.log()
+     * if necessary and aborting entirely if neither is available.
+     *
+     * This is useful as a default option to bring problems to the developer's
+     * attention without affecting the control flow of the software.
+     *
+     * @param {Warning} warning to log
+     *
+     * @return {undefined}
+     */
+    log: function( warning )
+    {
+        var dest;
+
+        console && ( dest = console.warn || console.log ) &&
+            dest( warning.message );
+    },
+};
+
diff --git a/test/test-warn-handlers.js b/test/test-warn-handlers.js
new file mode 100644
index 0000000..66d7a6e
--- /dev/null
+++ b/test/test-warn-handlers.js
@@ -0,0 +1,118 @@
+/**
+ * Tests core warning handlers
+ *
+ *  Copyright (C) 2010 Mike Gerwitz
+ *
+ *  This file is part of ease.js.
+ *
+ *  ease.js is free software: you can redistribute it and/or modify it under the
+ *  terms of the GNU Lesser General Public License as published by the Free
+ *  Software Foundation, either version 3 of the License, or (at your option)
+ *  any later version.
+ *
+ *  This program is distributed in the hope that it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
+ *  for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * @author  Mike Gerwitz
+ * @package test
+ */
+
+var common  = require( './common' ),
+    assert  = require( 'assert' ),
+    warn    = common.require( 'warn' ),
+    Warning = warn.Warning,
+
+    warning = Warning( Error( 'gninraw' ) )
+;
+
+
+/**
+ * The log warning handler should log warnings to the console
+ */
+( function testLogWarningHandlerLogsMessageToConsole()
+{
+    var logged = false,
+
+        // back up console ref
+        console_ = console
+    ;
+
+    // mock console
+    console = {
+        warn: function( message )
+        {
+            assert.equal( message, warning.message,
+                "Should log proper message to console"
+            );
+
+            logged = true;
+        },
+    };
+
+    // call handler with the warning
+    warn.handlers.log( warning );
+
+    assert.equal( logged, true,
+        "Message should be logged to console"
+    );
+
+    // restore console
+    console = console_;
+} )();
+
+
+/**
+ * Some environments may not have a console reference, or they may not have
+ * console.warn. In this case, we just want to make sure we don't throw an error
+ * when attempting to invoke undefined, or access a property of undefined.
+ */
+( function testLogWarningHandlerHandlesMissingConsole()
+{
+    // back up console
+    var console_ = console;
+
+    // destroy it
+    console = undefined;
+
+    // attempt to log
+    warn.handlers.log( warning );
+
+    // restore console
+    console = console_;
+} )();
+
+
+/**
+ * Furthermore, an environment may implement console.log(), but not
+ * console.warn(). By default, we use warn(), so let's ensure we can fall back
+ * to log() if warn() is unavailable.
+ */
+( function testLogWarningHandlerWillFallBackToLogMethodIfWarnIsMissing()
+{
+    // back up and overwrite console to contain only log()
+    var console_ = console,
+        given    = '';
+
+    console = {
+        log: function( message )
+        {
+            given = message;
+        }
+    };
+
+    // attempt to log
+    warn.handlers.log( warning );
+
+    assert.equal( given, warning.message,
+        "Should fall back to log() and log proper message"
+    );
+
+    // restore console
+    console = console_;
+} )();
+