[base][vector] Test constexpr factories

Test some constexpr factories. StaticCharVector is not actually
constexpr, this will be fixed in a follow-up CL.

R=leszeks@chromium.org

Bug: v8:10426
Change-Id: I16fdf79cd7d4b3f54d7cf73e15bdff2306810f06
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2154192
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67210}

src/utils/vector.h

@@ -21,6 +21,10 @@ namespace internal {
 template <typename T>
 class Vector {
  public:
+  using value_type = T;
+  using iterator = T*;
+  using const_iterator = const T*;
+
   constexpr Vector() : start_(nullptr), length_(0) {}
 
   constexpr Vector(T* data, size_t length) : start_(data), length_(length) {

test/unittests/utils/vector-unittest.cc

@@ -2,7 +2,10 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include <algorithm>
+
 #include "src/utils/utils.h"
+#include "testing/gmock-support.h"
 #include "testing/gtest-support.h"
 
 namespace v8 {
@@ -73,5 +76,24 @@ TEST(OwnedVectorConstruction, Equals) {
   EXPECT_EQ(init_vec1.as_vector(), init_vec2.as_vector());
 }
 
+// Test that the constexpr factory methods work.
+TEST(VectorTest, ConstexprFactories) {
+  static constexpr int kInit1[] = {4, 11, 3};
+  static constexpr auto kVec1 = ArrayVector(kInit1);
+  STATIC_ASSERT(kVec1.size() == 3);
+  EXPECT_THAT(kVec1, testing::ElementsAreArray(kInit1));
+
+  static constexpr auto kVec2 = VectorOf(kInit1, 2);
+  STATIC_ASSERT(kVec2.size() == 2);
+  EXPECT_THAT(kVec2, testing::ElementsAre(4, 11));
+
+  // TODO(clemensb): Use StaticCharVector.
+  static constexpr const char kInit3[] = "foobar";
+  static constexpr auto kVec3 =
+      VectorOf(kInit3, 6);  // StaticCharVector(kInit3);
+  STATIC_ASSERT(kVec3.size() == 6);
+  EXPECT_THAT(kVec3, testing::ElementsAreArray(kInit3, kInit3 + 6));
+}
+
 }  // namespace internal
 }  // namespace v8