Merge pull request #23 from magmo/as-better-expectEvent

Better expectEvent

Author: andrewgordstewart

utils/expectEvent.js

@@ -1,20 +1,24 @@
-const defaultMatcher = function (event) { return true };
+const _ = require('lodash');
+
 module.exports = {
-    expectEvent: function (contract, filter) {
-        const emitterWitness = jest.fn();
-        const eventPromise = new Promise((resolve, reject) => {
-            contract.on(filter, function () {
-                const event = arguments[arguments.length - 1];
-                emitterWitness();
-                resolve(event);
-            });
-    
-            // After 10s, we throw a timeout error
-            setTimeout(() => {
-                reject(new Error('timeout while waiting for event'));
-            }, 10000);
-        });
-    
-        return { emitterWitness, eventPromise };
+    expectEvent: async function (txOrTxResult, expectedEventName, expectedEventArgs={}) {
+        // Usage:
+        // Pass a transaction result, in which case await is unnecessary
+        // expectEvent(txResult, 'EventName', { argName: value })
+        // OR
+        // pass a transaction object
+        // await expectEvent(await someContract.someFunction(), 'EventName', { argName: value })
+
+        let txResult = txOrTxResult
+        if (txOrTxResult.wait) {
+            // in this case, we were passed the result of `await someContract.someFunction(args)`,
+            // which is the transasction got sent off, but hasn't yet been confirmed.
+            txResult = await txOrTxResult.wait();
+        }
+        const events = txResult.events;
+        const matchingEvents = events.filter(event => {
+            return event.event === expectedEventName &&  _.isMatch(event.args, expectedEventArgs)
+        })
+        expect(matchingEvents.length).toBeGreaterThan(0);
       }
 }