Formatter: Checkstyle

Created checkstyle formatter based off of the example here: http://www.jshint.com/docs/config/

`eslint -f checkstyle foo.js` will not produce output that looks like this:

<?xml version="1.0" encoding="utf-8"?>
<checkstyle version="4.3">
	<file name="foo.js">
		<error line="5" column="10" severity="error" message="Unexpected foo." />
	</file>
</checkstyle>

Fixes eslint#14

lib/formatters/checkstyle.js

@@ -0,0 +1,51 @@
+/**
+ * @fileoverview CheckStyle XML reporter
+ * @author Ian Christian Myers
+ */
+
+//------------------------------------------------------------------------------
+// Helper Functions
+//------------------------------------------------------------------------------
+
+function getMessageType(message, rules) {
+
+    if (message.fatal || rules[message.ruleId] === 2) {
+        return "error";
+    } else {
+        return "warning";
+    }
+
+}
+
+//------------------------------------------------------------------------------
+// Public Interface
+//------------------------------------------------------------------------------
+
+module.exports = function(results, config) {
+
+    var output = "",
+        rules = config.rules || {};
+
+    output += "<?xml version=\"1.0\" encoding=\"utf-8\"?>";
+    output += "<checkstyle version=\"4.3\">";
+
+    results.forEach(function(result) {
+        var messages = result.messages;
+
+        output += "<file name=\"" + result.filePath + "\">";
+
+        messages.forEach(function(message) {
+            output += "<error line=\"" + message.line + "\" " + 
+                "column=\"" + message.column + "\" " + 
+                "severity=\"" + getMessageType(message, rules) + "\" " + 
+                "message=\"" + message.message + "\" />";
+        });
+
+        output += "</file>";
+
+    });
+
+    output += "</checkstyle>";
+
+    return output;
+};

tests/lib/formatters/checkstyle.js

@@ -0,0 +1,129 @@
+/**
+ * @fileoverview Tests for checkstyle reporter.
+ * @author Nicholas C. Zakas
+ */
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+var vows = require("vows"),
+    assert = require("assert"),
+    formatter = require("../../../lib/formatters/checkstyle");
+
+//------------------------------------------------------------------------------
+// Tests
+//------------------------------------------------------------------------------
+
+vows.describe("formatter:checkstyle").addBatch({
+
+    "when passed a single message": {
+
+        topic: [{
+            filePath: "foo.js",
+            messages: [{
+                message: "Unexpected foo.",
+                line: 5,
+                column: 10,
+                ruleId: "foo"
+            }]
+        }],
+
+        "should return a string in the format filename: line x, col y, Error - z for errors": function(topic) {
+            var config = {
+                rules: { foo: 2 }
+            };
+
+            var result = formatter(topic, config);
+            assert.equal("<?xml version=\"1.0\" encoding=\"utf-8\"?><checkstyle version=\"4.3\"><file name=\"foo.js\"><error line=\"5\" column=\"10\" severity=\"error\" message=\"Unexpected foo.\" /></file></checkstyle>", result);
+        },
+
+        "should return a string in the format filename: line x, col y, Warning - z for warnings": function(topic) {
+            var config = {
+                rules: { foo: 1 }
+            };
+
+            var result = formatter(topic, config);
+            assert.equal("<?xml version=\"1.0\" encoding=\"utf-8\"?><checkstyle version=\"4.3\"><file name=\"foo.js\"><error line=\"5\" column=\"10\" severity=\"warning\" message=\"Unexpected foo.\" /></file></checkstyle>", result);
+        }
+
+    },
+
+    "when passed a fatal error message": {
+
+        topic: [{
+            filePath: "foo.js",
+            messages: [{
+                fatal: true,
+                message: "Unexpected foo.",
+                line: 5,
+                column: 10,
+                ruleId: "foo"
+            }]
+        }],
+
+        "should return a string in the format filename: line x, col y, Error - z": function(topic) {
+            var config = {};    // doesn't matter what's in the config for this test
+
+            var result = formatter(topic, config);
+            assert.equal("<?xml version=\"1.0\" encoding=\"utf-8\"?><checkstyle version=\"4.3\"><file name=\"foo.js\"><error line=\"5\" column=\"10\" severity=\"error\" message=\"Unexpected foo.\" /></file></checkstyle>", result);
+        }
+    },
+
+    "when passed multiple messages": {
+        topic: [{
+            filePath: "foo.js",
+            messages: [{
+                message: "Unexpected foo.",
+                line: 5,
+                column: 10,
+                ruleId: "foo"
+            }, {
+                message: "Unexpected bar.",
+                line: 6,
+                column: 11,
+                ruleId: "bar"
+            }]
+        }],
+
+        "should return a string with multiple entries": function(topic) {
+            var config = {
+                rules: { foo: 2, bar: 1 }
+            };
+
+            var result = formatter(topic, config);
+            assert.equal("<?xml version=\"1.0\" encoding=\"utf-8\"?><checkstyle version=\"4.3\"><file name=\"foo.js\"><error line=\"5\" column=\"10\" severity=\"error\" message=\"Unexpected foo.\" /><error line=\"6\" column=\"11\" severity=\"warning\" message=\"Unexpected bar.\" /></file></checkstyle>", result);
+        }
+
+    },
+
+    "when passed multiple files with 1 message each": {
+        topic: [{
+            filePath: "foo.js",
+            messages: [{
+                message: "Unexpected foo.",
+                line: 5,
+                column: 10,
+                ruleId: "foo"
+            }]
+        }, {
+            filePath: "bar.js",
+            messages: [{
+                message: "Unexpected bar.",
+                line: 6,
+                column: 11,
+                ruleId: "bar"
+            }]
+        }],
+
+        "should return a string with multiple entries": function(topic) {
+            var config = {
+                rules: { foo: 2, bar: 1 }
+            };
+
+            var result = formatter(topic, config);
+            assert.equal("<?xml version=\"1.0\" encoding=\"utf-8\"?><checkstyle version=\"4.3\"><file name=\"foo.js\"><error line=\"5\" column=\"10\" severity=\"error\" message=\"Unexpected foo.\" /></file><file name=\"bar.js\"><error line=\"6\" column=\"11\" severity=\"warning\" message=\"Unexpected bar.\" /></file></checkstyle>", result);
+        }
+    }
+
+    }).export(module);