adds utility to load json async

node_modules/c9/load-json.js

@@ -0,0 +1,40 @@
+"use strict";
+
+var fs = require("fs");
+
+/**
+ * A "safe" JSON loader. 
+ * 
+ * When parsing JSON we must wrap it in a try/catch block to prevent parsing 
+ * errors from crashing our process.
+ * 
+ * By wrapping json-parse as an async funciton we circumvent this problemn and
+ * follow the node-conventions for next(err, result)
+ */
+
+function parse(str, done) {
+    /**
+     * JSON.parse can block the event loop. setImmediate will push calls to .parse
+     * on a callback queue.
+     */
+    setImmediate(function(){
+        try {
+            var data = JSON.parse(str);
+            return done(null, data);
+        }
+        catch (err) {
+            return done(err);
+        }
+    });
+}
+
+module.exports.parse = parse;
+
+function load(path, done) {
+    fs.readFile(path, function(err, buf) {
+        if (err) return done(err);
+        return parse(buf.toString(), done);
+    });
+}
+
+module.exports.load = load;

node_modules/c9/load-json_test.js

@@ -0,0 +1,74 @@
+"use strict";
+"use server";
+
+require("c9/inline-mocha")(module);
+
+var assert = require("assert");
+var json = require("./load-json");
+var fs = require("fs");
+
+describe("parse", function() {
+    it("parses valid json", function(done) {
+        var input = {
+            hello: ["world"]
+        };
+
+        json.parse(JSON.stringify(input), function(err, parsed) {
+            assert.ok(!err, "No error: " + err);
+            assert.deepEqual(parsed, input);
+            done();
+        });
+    });
+
+    it("gives an error when input is not valid json", function(done) {
+        json.parse("!@$%", function(err) {
+            assert.ok(err, "Returned an error");
+            assert.ok(err.toString(), "SyntaxError: Unexpected token !");
+            done();
+        });
+    });
+});
+
+describe("load", function() {
+    function writetmp(data) {
+        var path = ["/tmp/tmpfile", Date.now().toString(36), (Math.random() * 10e16).toString(36)].join("-");
+        fs.writeFileSync(path, data);
+        return path;
+    }
+
+
+    it("returns an error if does not exist", function(done) {
+        json.load("doesnotexsit", function(err) {
+            assert.ok(err, "Returned an error");
+            assert.equal(err.toString(), "Error: ENOENT: no such file or directory, open 'doesnotexsit'");
+            done();
+        });
+    });
+
+    it("loads and parses a given file", function(done) {
+        var input = {
+            hello: ["world"]
+        };
+
+        var tmpfile = writetmp(JSON.stringify(input));
+
+        json.load(tmpfile, function(err, result) {
+            assert.ok(!err, "no err: " + err);
+            assert.deepEqual(result, input);
+            fs.unlinkSync(tmpfile);
+            done();
+        });
+
+    });
+
+    it("returns error if the file contains bad json", function(done) {
+        var tmpfile = writetmp("!@#$");
+
+        json.load(tmpfile, function(err, result) {
+            assert.ok(err, "Returned an error");
+            assert.ok(err.toString(), "SyntaxError: Unexpected token !");
+            fs.unlinkSync(tmpfile);
+            done();
+        });
+    });
+});