Added budget_service.mojom

third_party/WebKit/LayoutTests/http/tests/budget/budget-service-mock.js

+/**
+ * Mock implementation of the budget service.
+ */
+
+"use strict";
+
+const TEST_BUDGET_COST = 1.2;
+const TEST_BUDGET_AT = 2.3;
+const TEST_BUDGET_TIME = new Date().getTime();

[Peter Beverloo, 2016/08/22 17:57:55]

One thing to consider:

Rather than hard coding these values, you could add methods on the
BudgetServiceMock class enabling the test to indicate which values they expect.
For instance, you could consider having something like:

====================
class BudgetServiceMock {
  constructor(interfaceProvider) {
    // ...

    this.costs_ = new Map();
  }

  // ...

  getCost(operationType) {
    return Promise.resolve({ cost: this.costs_.get(operationType) || 0 });
  }

  setCostForTesting(operationType, cost) {
    this.costs_.set(operationType, cost);
  }
}
====================

And then in your test:

====================
promise_test(function() {
  const silentPushCost = 42;

  return budgetServiceMock.then(mock => {
    assert_own_property(Navigator.prototype, 'budget');

    mock.setCostForTesting("silent-push", silentPushCost);

    return navigator.budget.getCost("silent-push");
  }).then(cost => {
    assert_equals(cost, silentPushCost);
  });

}, 'BudgetService mock for GetCost should return correct results.');
====================

That completely localizes the knowledge, and removes the need for the constants.

It does require some diligence to avoid depending on the execution order of the
tests, so some sort of "clearOverridesForTesting" method might be advisable too.

[harkness, 2016/08/23 09:38:18]

I'll make this change in the next CL when I add in testing for Reserve. Right
now I've got a bunch of changes pending on this change, so I want to clear that
backlog.

+
+let budgetServiceMock = loadMojoModules(
+    'budgetServiceMock',
+    ['third_party/WebKit/public/platform/modules/budget_service/budget_service.mojom',
+     'mojo/public/js/router'
+    ]).then(mojo => {
+  let [budgetService, router] = mojo.modules;

[Peter Beverloo, 2016/08/22 17:57:55]

nit: s/let/const/

[harkness, 2016/08/23 09:38:18]

Done.

+
+  class BudgetServiceMock {
+    constructor(interfaceProvider) {
+      interfaceProvider.addInterfaceOverrideForTesting(
+          budgetService.BudgetService.name,
+          handle => this.connectBudgetService_(handle));
+
+      this.interfaceProvider_ = interfaceProvider;
+    }
+
+    connectBudgetService_(handle) {
+      this.budgetServiceStub_ = new budgetService.BudgetService.stubClass(this);
+      this.budgetServiceRouter_ = new router.Router(handle);
+      this.budgetServiceRouter_.setIncomingReceiver(this.budgetServiceStub_);
+    }
+
+    getCost(operationType) {
+      return Promise.resolve({ cost:TEST_BUDGET_COST });
+    }
+
+    getBudget() {
+      return Promise.resolve({ budget: [ { time:TEST_BUDGET_TIME, budget_at:TEST_BUDGET_AT } ] });
+    }
+  }
+  // Connect to the Mojo interface.

[Peter Beverloo, 2016/08/22 17:57:55]

nit: drop the comment. This doesn't actually "connect" to the interface, it
registers an override to whatever service is being provided by default.

[harkness, 2016/08/23 09:38:18]

Done.

+  return new BudgetServiceMock(mojo.interfaces);
+});