resolve relative paths

index.js

@@ -50,6 +50,8 @@ Liftoff.prototype.buildEnvironment = function (opts) {
 
   // make a copy of search paths that can be mutated for this run
   var searchPaths = this.searchPaths.slice();
+  // store the instance configName to use in closures without access to `this`
+  var configName = this.configName;
 
   // calculate current cwd
   var cwd = findCwd(opts);
@@ -113,6 +115,13 @@ Liftoff.prototype.buildEnvironment = function (opts) {
         'Encountered error when loading config file: ' + configFilePath
       );
     }
+
+    // resolve something like `{ gulpfile: "./abc.xyz" }` to the absolute path
+    // based on the path of the configFile
+    if (Object.prototype.hasOwnProperty.call(configFile, configName)) {
+      configFile[configName] = path.resolve(configFilePath, configFile[configName]);
+    }
+
     visited[configFilePath] = true;
     if (configFile && configFile.extends) {
       var nextCwd = path.dirname(configFilePath);
@@ -146,8 +155,6 @@ Liftoff.prototype.buildEnvironment = function (opts) {
     return loadConfig(cwd, startingLocation, defaultConfig);
   });
 
-  var configName = this.configName;
-
   var configPathOverride = arrayFind(Object.keys(config), function (key) {
     var cfg = config[key];
     if (Object.prototype.hasOwnProperty.call(cfg, configName)) {

test/fixtures/configfiles/override-config-path-relative.json

@@ -0,0 +1,3 @@
+{
+  "myappfile": "../override-the-config-path.js"
+}

test/index.js

@@ -575,8 +575,23 @@ describe('Liftoff', function () {
       var app = new Liftoff({
         name: 'myapp',
         configFiles: {
-          'override-config-path': [
-            { path: 'test/fixtures/configfiles', extensions: ['.js', '.json'] }
+          'override-config-path-absolute': [
+            { path: 'test/fixtures/configfiles', extensions: ['.js'] }
+          ],
+        },
+      });
+      app.prepare({}, function (env) {
+        expect(env.configPath).toMatch(/override-the-config-path\.js$/);
+        done();
+      });
+    });
+
+    it('resolves relative configPath if the configName key exists in the config', function (done) {
+      var app = new Liftoff({
+        name: 'myapp',
+        configFiles: {
+          'override-config-path-relative': [
+            { path: 'test/fixtures/configfiles', extensions: ['.json'] }
           ],
         },
       });