Added more test cases

- When the value of "main" is an empty string (empty_main)

- When the "main" parameter does not exist in package.json (missing_main)

- When the value of "main" is null (null_main)

test/resolver.js

@@ -272,6 +272,18 @@ test('path iterator', function (t) {
     });
 });
 
+test('empty main', function (t) {
+    t.plan(1);
+
+    var resolverDir = path.join(__dirname, 'resolver');
+    var dir = path.join(resolverDir, 'empty_main');
+
+    resolve('./empty_main', { basedir: resolverDir }, function (err, res, pkg) {
+        if (err) t.fail(err);
+        t.equal(res, path.join(dir, 'index.js'));
+    });
+});
+
 test('incorrect main', function (t) {
     t.plan(1);
 
@@ -284,11 +296,37 @@ test('incorrect main', function (t) {
     });
 });
 
+test('missing index', function (t) {
+    t.plan(2);
+
+    var resolverDir = path.join(__dirname, 'resolver');
+    resolve('./missing_index', { basedir: resolverDir }, function (err, res, pkg) {
+        t.ok(err instanceof Error);
+        t.equal(err && err.code, 'INCORRECT_PACKAGE_MAIN', 'error has correct error code');
+    });
+});
+
 test('missing main', function (t) {
+    t.plan(1);
+
     var resolverDir = path.join(__dirname, 'resolver');
+    var dir = path.join(resolverDir, 'missing_main');
+
     resolve('./missing_main', { basedir: resolverDir }, function (err, res, pkg) {
-        if (!err) t.fail('No error thrown when main was found missing.');
-        t.end();
+        if (err) t.fail(err);
+        t.equal(res, path.join(dir, 'index.js'));
+    });
+});
+
+test('null main', function (t) {
+    t.plan(1);
+
+    var resolverDir = path.join(__dirname, 'resolver');
+    var dir = path.join(resolverDir, 'null_main');
+
+    resolve('./null_main', { basedir: resolverDir }, function (err, res, pkg) {
+        if (err) t.fail(err);
+        t.equal(res, path.join(dir, 'index.js'));
     });
 });
 

test/resolver/empty_main/package.json

@@ -0,0 +1,3 @@
+{
+  "main": ""
+}

test/resolver/missing_index/package.json

@@ -0,0 +1,3 @@
+{
+  "main": "index.js"
+}

test/resolver/missing_main/package.json

@@ -1,3 +1,3 @@
 {
-  "main": "index.js"
+  "notmain": "index.js"
 }

test/resolver/null_main/package.json

@@ -0,0 +1,3 @@
+{
+  "main": null
+}