GoogleTest hello world.

./build and ./test work automatically when cwd is inside userland/libs/XXX
without --package-all.

userland/libs/googletest/main.cpp

@@ -0,0 +1,27 @@
+#include <utility>
+#include <vector>
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+using testing::ElementsAre;
+using testing::Pair;
+
+TEST(MainTest, MyTest0) {
+    EXPECT_EQ(1, 1);
+
+    // Array comparison.
+    // https://stackoverflow.com/questions/1460703/comparison-of-arrays-in-google-test
+    ASSERT_THAT(
+        (std::vector<int>{5, 10, 15}),
+        ElementsAre(5, 10, 15)
+    );
+    ASSERT_THAT(
+        (std::vector<std::pair<int, int>>{{1, -1}, {2, -2}}),
+        ElementsAre(Pair(1, -1), Pair(2, -2))
+    );
+}
+
+TEST(MainTest, MyTest1) {
+    EXPECT_EQ(1, 1);
+}