Add tests for IsColorModelSelected()

Test two simple cases, COLOR and GRAY, and add death tests for corner
cases.

Bug: 1069537
Change-Id: I892da4f1daa384d795fb94a5810a698dfc9544b2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2148093Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Daniel Hosseinian <dhoss@chromium.org>
Cr-Commit-Position: refs/heads/master@{#758891}

printing/BUILD.gn

@@ -331,6 +331,7 @@ test("printing_unittests") {
     "page_range_unittest.cc",
     "page_setup_unittest.cc",
     "print_settings_conversion_unittest.cc",
+    "print_settings_unittest.cc",
     "printing_test.h",
     "printing_utils_unittest.cc",
     "units_unittest.cc",

printing/print_settings_unittest.cc

+// Copyright 2020 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 "printing/print_settings.h"
+
+#include "base/test/gtest_util.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace printing {
+
+TEST(PrintSettingsTest, IsColorModelSelected) {
+  {
+    base::Optional<bool> color(IsColorModelSelected(COLOR));
+    ASSERT_TRUE(color.has_value());
+    EXPECT_TRUE(color.value());
+  }
+  {
+    base::Optional<bool> gray(IsColorModelSelected(GRAY));
+    ASSERT_TRUE(gray.has_value());
+    EXPECT_FALSE(gray.value());
+  }
+  {
+    // Test lower bound validity.
+    base::Optional<bool> lower(IsColorModelSelected(UNKNOWN_COLOR_MODEL + 1));
+    EXPECT_TRUE(lower.has_value());
+  }
+  {
+    // Test upper bound validity.
+    base::Optional<bool> upper(IsColorModelSelected(COLOR_MODEL_LAST));
+    EXPECT_TRUE(upper.has_value());
+  }
+}
+
+TEST(PrintSettingsDeathTest, IsColorModelSelectedUnknown) {
+  ::testing::FLAGS_gtest_death_test_style = "threadsafe";
+  EXPECT_DCHECK_DEATH(IsColorModelSelected(UNKNOWN_COLOR_MODEL));
+  EXPECT_DCHECK_DEATH(IsColorModelSelected(UNKNOWN_COLOR_MODEL - 1));
+  EXPECT_DCHECK_DEATH(IsColorModelSelected(COLOR_MODEL_LAST + 1));
+}
+
+}  // namespace printing