Some changes to the resolver API, add more tests.

lib/resolve/Resolver.js

@@ -39,25 +39,51 @@ Resolver.prototype.getTempDir = function () {
 };
 
 Resolver.prototype.hasNew = function (canonicalPkg) {
-    return Q.resolve(true);
+    var that = this,
+        promise,
+        metaFile;
+
+    // If already working, error out
+    if (this._working) {
+        return Q.reject(createError('Already working', 'EWORKING'));
+    }
+
+    this._working = true;
+
+    // Avoid reading the package meta if _hasNew was not rewritten
+    if (this._hasNew === Resolver.prototype._hasNew) {
+        promise = this._hasNew();
+    // Otherwise call _hasNew with both the package meta and the canonical package
+    } else {
+        metaFile = path.join(canonicalPkg, '.bower.json');
+        promise = Q.nfcall(fs.readFile, metaFile)
+        .then(function (contents) {
+            var pkgMeta = JSON.parse(contents.toString());
+            return that._hasNew(pkgMeta, canonicalPkg);
+        }, function () {
+            return true;  // Simply resolve to true if there was an error reading the meta
+        });
+    }
+
+    return promise.fin(function () {
+        that._working = false;
+    });
 };
 
 Resolver.prototype.resolve = function () {
     var that = this;
 
-    // If already resolving, throw an error
-    // We don't actually reject a promise because this is a
-    // serious logic error
-    if (this._resolving) {
-        throw new Error('Already resolving');
+    // If already working, error out
+    if (this._working) {
+        return Q.reject(createError('Already working', 'EWORKING'));
     }
 
-    this._resolving = true;
+    this._working = true;
 
     // Create temporary dir
     return this._createTempDir()
     // Resolve self
-    .then(this._resolveSelf.bind(this))
+    .then(this._resolve.bind(this))
     // Read json, generating the package meta
     .then(function () {
         return that._readJson(that._tempDir);
@@ -71,14 +97,15 @@ Resolver.prototype.resolve = function () {
         ]);
     })
     .then(function () {
-        that._resolving = false;
         // Resolve with the folder
         return that._tempDir;
     }, function (err) {
-        that._resolving = false;
         // If something went wrong, unset the temporary dir
         that._tempDir = null;
         throw err;
+    })
+    .fin(function () {
+        that._working = false;
     });
 };
 
@@ -93,12 +120,16 @@ Resolver.clearRuntimeCache = function () {};
 // -----------------
 
 // Abstract function that should be implemented by concrete resolvers
-Resolver.prototype._resolveSelf = function () {
-    throw new Error('_resolveSelf not implemented');
+Resolver.prototype._resolve = function () {
+    throw new Error('_resolve not implemented');
 };
 
 // -----------------
 
+Resolver.prototype._hasNew = function (pkgMeta, canonicalPkg) {
+    return Q.resolve(true);
+};
+
 Resolver.prototype._createTempDir = function () {
     var baseDir = path.join(tmp.tmpdir, 'bower');