Changes to Counter (#1332)

* rename Index.currentId to current

* use += operator for clarity

* rename Counter.Index to Counter.Counter

* move Counter to drafts

(cherry picked from commit 3e55408cb5)

test/drafts/Counter.test.js

@@ -0,0 +1,40 @@
+
+const Counter = artifacts.require('CounterImpl');
+
+require('chai')
+  .use(require('chai-bignumber')(web3.BigNumber))
+  .should();
+
+const EXPECTED = [1, 2, 3, 4];
+const KEY1 = web3.sha3('key1');
+const KEY2 = web3.sha3('key2');
+
+contract('Counter', function ([_, owner]) {
+  beforeEach(async function () {
+    this.mock = await Counter.new({ from: owner });
+  });
+
+  context('custom key', async function () {
+    it('should return expected values', async function () {
+      for (const expectedId of EXPECTED) {
+        await this.mock.doThing(KEY1, { from: owner });
+        const actualId = await this.mock.theId();
+        actualId.should.be.bignumber.equal(expectedId);
+      }
+    });
+  });
+
+  context('parallel keys', async function () {
+    it('should return expected values for each counter', async function () {
+      for (const expectedId of EXPECTED) {
+        await this.mock.doThing(KEY1, { from: owner });
+        let actualId = await this.mock.theId();
+        actualId.should.be.bignumber.equal(expectedId);
+
+        await this.mock.doThing(KEY2, { from: owner });
+        actualId = await this.mock.theId();
+        actualId.should.be.bignumber.equal(expectedId);
+      }
+    });
+  });
+});