Improve require priority

Priority: a.js > a.json > a/index.js

Close #22

lib/file.js

@@ -128,7 +128,8 @@ function tryFile(src, cwd) {
     fileArray.push(src + '.js');
   }
   if (!extname(src)) {
-    fileArray.push(src + '/index.js');
+    fileArray.push(src + '.json');
+    fileArray.push(join(src, 'index.js'));
   }
 
   for (var i in fileArray) {

test/fixtures/spm/require-directory/index.js

@@ -1 +1 @@
-require('./lib');
+require('./lib/');

test/fixtures/spm/require-priority/a.js

@@ -0,0 +1 @@
+module.exports = 'a.js';

test/fixtures/spm/require-priority/a.json

@@ -0,0 +1 @@
+{"a":"json"}

test/fixtures/spm/require-priority/b.json

@@ -0,0 +1 @@
+{"b":"json"}

test/fixtures/spm/require-priority/b/index.js

@@ -0,0 +1 @@
+module.exports = 'b/index.js';

test/fixtures/spm/require-priority/index.js

@@ -0,0 +1,2 @@
+require('./a');
+require('./b');

test/fixtures/spm/require-priority/package.json

@@ -0,0 +1,4 @@
+{
+  "name": "require-priority",
+  "version": "1.0.0"
+}

test/spm.test.js

@@ -213,6 +213,14 @@ describe('Father.SpmPackage', function() {
     pkg.files['index.js'].dependencies.should.eql(['./lib.js']);
   });
 
+  it('should require priority a.js > a.json > a/index.js', function() {
+    var pkg = getPackage('require-priority');
+    should.exist(pkg.files['a.js']);
+    should.not.exist(pkg.files['a.json']);
+    should.exist(pkg.files['b.json']);
+    should.not.exist(pkg.files['b/index.js']);
+  });
+
   it('should support relative main', function() {
     var pkg = getPackage('relative-main');
     Object.keys(pkg.files).length.should.eql(1);