Add arc_process_unittest.cc

arc::ArcProcess has a relatively complex operator<() which should be
paired with a test. I'd add this before adding more changes for
crbug.com/706048.

BUG=None
TEST=try

Review-Url: https://codereview.chromium.org/2853633002
Cr-Commit-Position: refs/heads/master@{#468382}

chrome/browser/chromeos/BUILD.gn

@@ -1571,6 +1571,7 @@ source_set("unit_tests") {
     "arc/notification/arc_provision_notification_service_unittest.cc",
     "arc/optin/arc_terms_of_service_default_negotiator_unittest.cc",
     "arc/policy/arc_policy_bridge_unittest.cc",
+    "arc/process/arc_process_unittest.cc",
     "attestation/attestation_ca_client_unittest.cc",
     "attestation/attestation_policy_observer_unittest.cc",
     "attestation/fake_certificate.cc",

chrome/browser/chromeos/arc/process/arc_process_unittest.cc

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/chromeos/arc/process/arc_process.h"
+
+#include <assert.h>
+#include <list>
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace arc {
+
+namespace {
+
+// Tests that ArcProcess objects can be sorted by their priority (higher to
+// lower). This is critical for the OOM handler to work correctly.
+TEST(ArcProcess, TestSorting) {
+  constexpr int64_t kNow = 1234567890;
+
+  std::list<ArcProcess> processes;  // use list<> for emplace_front.
+  processes.emplace_back(0, 0, "process 0", mojom::ProcessState::PERSISTENT,
+                         false /* is_foreground */, kNow + 1);
+  processes.emplace_front(1, 1, "process 1", mojom::ProcessState::PERSISTENT,
+                          false, kNow);
+  processes.emplace_back(2, 2, "process 2", mojom::ProcessState::LAST_ACTIVITY,
+                         false, kNow);
+  processes.emplace_front(3, 3, "process 3", mojom::ProcessState::LAST_ACTIVITY,
+                          false, kNow + 1);
+  processes.emplace_back(4, 4, "process 4", mojom::ProcessState::CACHED_EMPTY,
+                         false, kNow + 1);
+  processes.emplace_front(5, 5, "process 5", mojom::ProcessState::CACHED_EMPTY,
+                          false, kNow);
+  processes.sort();
+
+  static_assert(
+      mojom::ProcessState::PERSISTENT < mojom::ProcessState::LAST_ACTIVITY,
+      "unexpected enum values");
+  static_assert(
+      mojom::ProcessState::LAST_ACTIVITY < mojom::ProcessState::CACHED_EMPTY,
+      "unexpected enum values");
+
+  std::list<ArcProcess>::const_iterator it = processes.begin();
+  // 0 should have higher priority since its last_activity_time is more recent.
+  EXPECT_EQ(0, it->pid());
+  ++it;
+  EXPECT_EQ(1, it->pid());
+  ++it;
+  // Same, 3 should have higher priority.
+  EXPECT_EQ(3, it->pid());
+  ++it;
+  EXPECT_EQ(2, it->pid());
+  ++it;
+  // Same, 4 should have higher priority.
+  EXPECT_EQ(4, it->pid());
+  ++it;
+  EXPECT_EQ(5, it->pid());
+}
+
+}  // namespace
+
+}  // namespace arc