Moved Escrows into an escrow subdirectory, improved docs. (#1430)

* Moved Escrows into an escrow subdirectory, improved docs.

* Fixed escrow mock.

* Fixed some more imports.

test/payment/escrow/ConditionalEscrow.test.js

@@ -0,0 +1,40 @@
+const { shouldBehaveLikeEscrow } = require('./Escrow.behavior');
+
+const shouldFail = require('../../helpers/shouldFail');
+const { ether } = require('../../helpers/ether');
+
+const BigNumber = web3.BigNumber;
+
+require('chai')
+  .use(require('chai-bignumber')(BigNumber))
+  .should();
+
+const ConditionalEscrowMock = artifacts.require('ConditionalEscrowMock');
+
+contract('ConditionalEscrow', function ([_, owner, payee, ...otherAccounts]) {
+  beforeEach(async function () {
+    this.escrow = await ConditionalEscrowMock.new({ from: owner });
+  });
+
+  context('when withdrawal is allowed', function () {
+    beforeEach(async function () {
+      await Promise.all(otherAccounts.map(payee => this.escrow.setAllowed(payee, true)));
+    });
+
+    shouldBehaveLikeEscrow(owner, otherAccounts);
+  });
+
+  context('when withdrawal is disallowed', function () {
+    const amount = ether(23.0);
+
+    beforeEach(async function () {
+      await this.escrow.setAllowed(payee, false);
+    });
+
+    it('reverts on withdrawals', async function () {
+      await this.escrow.deposit(payee, { from: owner, value: amount });
+
+      await shouldFail.reverting(this.escrow.withdraw(payee, { from: owner }));
+    });
+  });
+});