Add ability to list service names.

README.md

@@ -494,6 +494,9 @@ function getGitHubService(label) {
 }
 ```
 
+You can list all of the service names you've previously stored tokens for using
+`OAuth2.getServiceNames(propertyStore)`.
+
 ## Compatibility
 
 This library was designed to work with any OAuth2 provider, but because of small

src/OAuth2.js

@@ -28,6 +28,8 @@ var TOKEN_FORMAT = {
   FORM_URL_ENCODED: 'application/x-www-form-urlencoded'
 };
 
+var STORAGE_PREFIX_ = 'oauth2.';
+
 /**
  * Creates a new OAuth2 service with the name specified. It's usually best to
  * create and configure your service once at the start of your script, and then
@@ -53,10 +55,34 @@ function getRedirectUri(optScriptId) {
       '/usercallback';
 }
 
+/**
+ * Gets the list of services with tokens stored in the given property store.
+ * This is useful if you connect to the same API with multiple accounts and
+ * need to keep track of them. If no stored tokens are found this will return
+ * an empty array.
+ * @param {PropertiesService.Properties} propertyStore The properties to check.
+ * @return {Array.<string>} The service names.
+ */
+function getServiceNames(propertyStore) {
+  var props = propertyStore.getProperties();
+  return Object.keys(props).filter(function(key) {
+    var parts = key.split('.');
+    return key.indexOf(STORAGE_PREFIX_) == 0 && parts.length > 1 && parts[1];
+  }).map(function(key) {
+    return key.split('.')[1];
+  }).reduce(function(result, key) {
+    if (result.indexOf(key) < 0) {
+      result.push(key);
+    }
+    return result;
+  }, []);
+}
+
 if (typeof module === 'object') {
   module.exports = {
     createService: createService,
     getRedirectUri: getRedirectUri,
+    getServiceNames: getServiceNames,
     TOKEN_FORMAT: TOKEN_FORMAT
   };
 }

src/Service.js

@@ -609,7 +609,7 @@ Service_.prototype.refresh = function() {
  */
 Service_.prototype.getStorage = function() {
   if (!this.storage_) {
-    var prefix = 'oauth2.' + this.serviceName_;
+    var prefix = STORAGE_PREFIX_ + this.serviceName_;
     this.storage_ = new Storage_(prefix, this.propertyStore_, this.cache_);
   }
   return this.storage_;

test/test.js

@@ -33,6 +33,53 @@ var mocks = {
 };
 var OAuth2 = gas.require('./src', mocks);
 
+describe('OAuth2', function() {
+  describe('#getServiceNames()', function() {
+    it('should return the service names for stored tokens', function() {
+      var props = new MockProperties({
+        'oauth2.foo': '{"access_token": "abc"}',
+        'oauth2.bar': '{"access_token": "abc"}',
+      });
+
+      var names = OAuth2.getServiceNames(props);
+
+      assert.deepEqual(names, ['foo', 'bar']);
+    });
+
+    it('should return an empty array when no tokens are stored', function() {
+      var props = new MockProperties();
+
+      var names = OAuth2.getServiceNames(props);
+
+      assert.deepEqual(names, []);
+    });
+
+    it('should ignore keys without a service name', function() {
+      var props = new MockProperties({
+        'oauth2.': 'foo',
+        'oauth2..bar': 'bar',
+      });
+
+      var names = OAuth2.getServiceNames(props);
+
+      assert.deepEqual(names, []);
+    });
+
+    it('should not have duplicate names when there are custom keys',
+        function() {
+      var props = new MockProperties({
+        'oauth2.foo': '{"access_token": "abc"}',
+        'oauth2.foo.extra': 'my extra stuff',
+        'oauth2.foo.extra2': 'more extra stuff',
+      });
+
+      var names = OAuth2.getServiceNames(props);
+
+      assert.deepEqual(names, ['foo']);
+    });
+  });
+});
+
 describe('Service', function() {
   describe('#getToken()', function() {
     it('should return null when no token is stored', function() {