AK: Add tests for type traits and IndexSequence

Use TypeLists to add test for IsIntegral, IsFloatingPoint, IsVoid,
IsNullPointer, IsArithmetic, IsFundamental, and AddConst type traits.

More can "easily" be added once the TypeList and macro magic is squinted
at for long enough :).

3 files changed, 167 insertions, 0 deletions

diff --git a/AK/Tests/CMakeLists.txt b/AK/Tests/CMakeLists.txt
index aba78f9409..02ea1e5ac1 100644
--- a/AK/Tests/CMakeLists.txt
+++ b/AK/Tests/CMakeLists.txt
@@ -15,6 +15,7 @@ set(AK_TEST_SOURCES
     TestFormat.cpp
     TestHashFunctions.cpp
     TestHashMap.cpp
+    TestIndexSequence.cpp
     TestIPv4Address.cpp
     TestJSON.cpp
     TestLexicalPath.cpp
@@ -35,6 +36,7 @@ set(AK_TEST_SOURCES
     TestStringView.cpp
     TestTrie.cpp
     TestTypedTransfer.cpp
+    TestTypeTraits.cpp
     TestURL.cpp
     TestUtf8.cpp
     TestVector.cpp
diff --git a/AK/Tests/TestIndexSequence.cpp b/AK/Tests/TestIndexSequence.cpp
new file mode 100644
index 0000000000..8ae15cfea5
--- /dev/null
+++ b/AK/Tests/TestIndexSequence.cpp
@@ -0,0 +1,70 @@
+/*
+ * Copyright (c) 2020, the SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <AK/StdLibExtras.h>
+#include <AK/TestSuite.h>
+#include <AK/TypeList.h>
+
+template<typename F, typename... Args>
+F for_each_argument(F f, Args&&... args)
+{
+    (f(forward<Args>(args)), ...);
+    return f;
+}
+
+template<typename T, T... ints>
+void verify_sequence(IntegerSequence<T, ints...> seq, std::initializer_list<T> expected)
+{
+    EXPECT_EQ(seq.size(), expected.size());
+    for_each_argument([idx = expected.begin()](T t) mutable { EXPECT_EQ(t, *(idx++)); }, ints...);
+}
+
+TEST_CASE(TestIndexSequence)
+{
+    constexpr auto integer_seq1 = IntegerSequence<int, 0, 1, 2, 3, 4> {};
+    constexpr auto integer_seq2 = MakeIntegerSequence<int, 5> {};
+    static_assert(IsSame<decltype(integer_seq1), decltype(integer_seq2)>::value, "");
+
+    static_assert(integer_seq1.size() == 5, "");
+    static_assert(integer_seq2.size() == 5, "");
+
+    constexpr auto index_seq1 = IndexSequence<0, 1, 2> {};
+    constexpr auto index_seq2 = MakeIndexSequence<3> {};
+    static_assert(IsSame<decltype(index_seq1), decltype(index_seq2)>::value, "");
+
+    verify_sequence(MakeIndexSequence<10> {}, std::initializer_list<unsigned> { 0U, 1U, 2U, 3U, 4U, 5U, 6U, 7U, 8U, 9U });
+    verify_sequence(MakeIntegerSequence<long, 16> {}, std::initializer_list<long> { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 });
+}
+
+TEST_CASE(TypeList)
+{
+    using MyTypes = TypeList<int, bool, char>;
+    static_assert(IsSame<MyTypes::Type<0>, int>::value, "");
+    static_assert(IsSame<MyTypes::Type<1>, bool>::value, "");
+    static_assert(IsSame<MyTypes::Type<2>, char>::value, "");
+}
+
+TEST_MAIN(IndexSequence);
diff --git a/AK/Tests/TestTypeTraits.cpp b/AK/Tests/TestTypeTraits.cpp
new file mode 100644
index 0000000000..0492160a9a
--- /dev/null
+++ b/AK/Tests/TestTypeTraits.cpp
@@ -0,0 +1,95 @@
+/*
+ * Copyright (c) 2020, the SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <AK/StdLibExtras.h>
+#include <AK/TestSuite.h>
+#include <AK/TypeList.h>
+
+#define STATIC_EXPECT_EQ(lhs, rhs) \
+    static_assert(IsSame<lhs, rhs>::value, "");
+
+#define STATIC_EXPECT_FALSE(Expression) \
+    static_assert(!Expression::value, "");
+
+#define STATIC_EXPECT_TRUE(Expression) \
+    static_assert(Expression::value, "");
+
+#define EXPECT_TRAIT_TRUE(trait, ...)                                     \
+    for_each_type<TypeList<__VA_ARGS__>>([]<typename T>(TypeWrapper<T>) { \
+        STATIC_EXPECT_TRUE(trait<T>);                                     \
+    })
+
+#define EXPECT_TRAIT_FALSE(trait, ...)                                    \
+    for_each_type<TypeList<__VA_ARGS__>>([]<typename T>(TypeWrapper<T>) { \
+        STATIC_EXPECT_FALSE(trait<T>);                                    \
+    })
+
+#define EXPECT_EQ_WITH_TRAIT(trait, ListA, ListB)                                                   \
+    for_each_type_zipped<ListA, ListB>([]<typename A, typename B>(TypeWrapper<A>, TypeWrapper<B>) { \
+        STATIC_EXPECT_EQ(typename trait<A>::Type, B);                                               \
+    })
+
+struct Empty {
+};
+
+TEST_CASE(FundamentalTypeClassification)
+{
+    EXPECT_TRAIT_TRUE(IsVoid, void);
+    EXPECT_TRAIT_FALSE(IsVoid, int, Empty, nullptr_t);
+
+    EXPECT_TRAIT_TRUE(IsNullPointer, std::nullptr_t);
+    EXPECT_TRAIT_FALSE(IsNullPointer, void, int, Empty, decltype(0));
+
+    EXPECT_TRAIT_TRUE(IsFloatingPoint, float, double, long double);
+    EXPECT_TRAIT_FALSE(IsFloatingPoint, int, Empty, std::nullptr_t, void);
+
+    EXPECT_TRAIT_TRUE(IsArithmetic, float, double, long double, bool, size_t);
+    EXPECT_TRAIT_TRUE(IsArithmetic, char, signed char, unsigned char, char8_t, char16_t, char32_t);
+    EXPECT_TRAIT_TRUE(IsArithmetic, short, int, long, long long);
+    EXPECT_TRAIT_TRUE(IsArithmetic, unsigned short, unsigned int, unsigned long, unsigned long long);
+
+    EXPECT_TRAIT_FALSE(IsArithmetic, void, std::nullptr_t, Empty);
+
+    EXPECT_TRAIT_TRUE(IsFundamental, void, std::nullptr_t);
+    EXPECT_TRAIT_TRUE(IsFundamental, float, double, long double, bool, size_t);
+    EXPECT_TRAIT_TRUE(IsFundamental, char, signed char, unsigned char, char8_t, char16_t, char32_t);
+    EXPECT_TRAIT_TRUE(IsFundamental, short, int, long, long long);
+    EXPECT_TRAIT_TRUE(IsFundamental, unsigned short, unsigned int, unsigned long, unsigned long long);
+
+    EXPECT_TRAIT_FALSE(IsFundamental, Empty, int*, int&);
+}
+
+TEST_CASE(AddConst)
+{
+    // clang-format off
+    using NoConstList =  TypeList<int,       const int, Empty,       const Empty>;
+    using YesConstList = TypeList<const int, const int, const Empty, const Empty>;
+    // clang-format on
+
+    EXPECT_EQ_WITH_TRAIT(AddConst, NoConstList, YesConstList);
+}
+
+TEST_MAIN(TypeTraits)