supportsSubscriptions method added to providers

packages/web3-providers-http/src/index.js

@@ -120,5 +120,8 @@ HttpProvider.prototype.disconnect = function () {
     //NO OP
 };
 
+HttpProvider.prototype.supportsSubscriptions = function () {
+    return false;
+};
 
 module.exports = HttpProvider;

packages/web3-providers-ipc/src/index.js

@@ -311,5 +311,12 @@ IpcProvider.prototype.reset = function () {
     this.addDefaultEvents();
 };
 
+/**
+ * @returns {boolean}
+ */
+IpcProvider.prototype.supportsSubscriptions = function () {
+    return true;
+};
+
 module.exports = IpcProvider;
 

packages/web3-providers-ws/src/index.js

@@ -404,4 +404,11 @@ WebsocketProvider.prototype.disconnect = function () {
     }
 };
 
+/**
+ * @returns {boolean}
+ */
+WebsocketProvider.prototype.supportsSubscriptions = function () {
+    return true;
+};
+
 module.exports = WebsocketProvider;