chromium/chrome/test/base/mixin_based_in_process_browser_test.h

// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CHROME_TEST_BASE_MIXIN_BASED_IN_PROCESS_BROWSER_TEST_H_
#define CHROME_TEST_BASE_MIXIN_BASED_IN_PROCESS_BROWSER_TEST_H_

#include <memory>
#include <vector>

#include "base/memory/raw_ptr.h"
#include "chrome/test/base/in_process_browser_test.h"

//
// InProcessBrowserTestMixin enables writing isolated test helpers which depend
// on the standard test lifecycle but should not be test bases.
//
// A new mixin is created by deriving from InProcessBrowserTestMixin and
// overriding methods as needed.
//
//   class MyMixin : public InProcessBrowserTestMixin {
//    public:
//     explicit MyMixin(InProcessBrowserTestMixinHost* host)
//         : InProcessBrowserTestMixin(host) {}
//      MyMixin(const MyMixin&) = delete;
//      MyMixin& operator=(const MyMixin&) = delete;
//     ~MyMixin() override = default;
//
//     // InProcessBrowserTestMixin:
//     void SetUpCommandLine(base::CommandLine* command_line) { /* ... */ }
//
//   };
//
//
// To use the mixin, declare it as a member variable on the class and call the
// constructor with the InProcessBrowserTestMixinHost also declared on the class
// (or parent class). The mixin will register itself with the host and the host
// will invoke all registered mixin methods.
//
// For example, here is how to use MixinBasedInProcessBrowserTest:
//
//   class SimpleUsage : public MixinBasedInProcessBrowserTest {
//    public:
//     SimpleUsage() = default;
//     SimpleUsage(const SimpleUsage&) = delete;
//     SimpleUsage& operator=(const SimpleUsage&) = delete;
//     ~SimpleUsage() override = default;
//
//    private:
//     MyMixin my_mixin_{&mixin_host_};
//     SomeOtherMixin some_other_mixin_{&mixin_host_};
//   };
//
//
// See WizardInProcessBrowserTest for an example of how to correctly embed a
// mixin host.
//

class InProcessBrowserTestMixinHost;

// Derive from this type to create a class which depends on the test lifecycle
// without also becoming a test base.
class InProcessBrowserTestMixin { … };

// The mixin host executes the callbacks on the mixin instances.
class InProcessBrowserTestMixinHost final { … };

// An InProcessBrowserTest which supports mixins.
class MixinBasedInProcessBrowserTest : public InProcessBrowserTest { … };

#endif  // CHROME_TEST_BASE_MIXIN_BASED_IN_PROCESS_BROWSER_TEST_H_