[chttp2] Rework settings management to be a c++ type (#35449)

Closes #35449

COPYBARA_INTEGRATE_REVIEW=https://github.com/grpc/grpc/pull/35449 from ctiller:h2-settings f67e542a8b557617838e19ace37250ecff25172b
PiperOrigin-RevId: 597970333

2 files changed, 531 insertions, 0 deletions

diff --git a/test/core/transport/chttp2/BUILD b/test/core/transport/chttp2/BUILD
index 77ce6b4d10..1c11d2f554 100644
--- a/test/core/transport/chttp2/BUILD
+++ b/test/core/transport/chttp2/BUILD
@@ -446,3 +446,20 @@ grpc_cc_test(
         "//test/core/util:grpc_test_util",
     ],
 )
+
+grpc_cc_test(
+    name = "http2_settings_test",
+    srcs = [
+        "http2_settings_test.cc",
+    ],
+    external_deps = [
+        "gtest",
+    ],
+    language = "C++",
+    deps = [
+        "//:gpr",
+        "//:grpc",
+        "//src/core:http2_settings",
+        "//test/core/util:grpc_test_util",
+    ],
+)
diff --git a/test/core/transport/chttp2/http2_settings_test.cc b/test/core/transport/chttp2/http2_settings_test.cc
new file mode 100644
index 0000000000..776a131be4
--- /dev/null
+++ b/test/core/transport/chttp2/http2_settings_test.cc
@@ -0,0 +1,514 @@
+// Copyright 2024 gRPC authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "src/core/ext/transport/chttp2/transport/http2_settings.h"
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+
+namespace grpc_core {
+
+TEST(Http2SettingsTest, CanSetAndRetrieveSettings) {
+  Http2Settings settings;
+  settings.SetHeaderTableSize(1);
+  settings.SetEnablePush(true);
+  settings.SetMaxConcurrentStreams(3);
+  settings.SetInitialWindowSize(4);
+  settings.SetMaxFrameSize(50000);
+  settings.SetMaxHeaderListSize(6);
+  settings.SetAllowTrueBinaryMetadata(true);
+  settings.SetPreferredReceiveCryptoMessageSize(77777);
+  EXPECT_EQ(settings.header_table_size(), 1u);
+  EXPECT_EQ(settings.enable_push(), true);
+  EXPECT_EQ(settings.max_concurrent_streams(), 3u);
+  EXPECT_EQ(settings.initial_window_size(), 4u);
+  EXPECT_EQ(settings.max_frame_size(), 50000u);
+  EXPECT_EQ(settings.max_header_list_size(), 6u);
+  EXPECT_EQ(settings.allow_true_binary_metadata(), true);
+  EXPECT_EQ(settings.preferred_receive_crypto_message_size(), 77777u);
+  settings.SetHeaderTableSize(10);
+  settings.SetEnablePush(false);
+  settings.SetMaxConcurrentStreams(30);
+  settings.SetInitialWindowSize(40);
+  settings.SetMaxFrameSize(5000000);
+  settings.SetMaxHeaderListSize(60);
+  settings.SetAllowTrueBinaryMetadata(false);
+  settings.SetPreferredReceiveCryptoMessageSize(70000);
+  EXPECT_EQ(settings.header_table_size(), 10u);
+  EXPECT_EQ(settings.enable_push(), false);
+  EXPECT_EQ(settings.max_concurrent_streams(), 30u);
+  EXPECT_EQ(settings.initial_window_size(), 40u);
+  EXPECT_EQ(settings.max_frame_size(), 5000000u);
+  EXPECT_EQ(settings.max_header_list_size(), 60u);
+  EXPECT_EQ(settings.allow_true_binary_metadata(), false);
+  EXPECT_EQ(settings.preferred_receive_crypto_message_size(), 70000u);
+}
+
+TEST(Http2SettingsTest, InitialWindowSizeLimits) {
+  Http2Settings settings;
+  settings.SetInitialWindowSize(0);
+  EXPECT_EQ(settings.initial_window_size(), 0u);
+  settings.SetInitialWindowSize(0x7fffffff);
+  EXPECT_EQ(settings.initial_window_size(), 0x7fffffffu);
+  settings.SetInitialWindowSize(0x80000000);
+  EXPECT_EQ(settings.initial_window_size(), 0x7fffffffu);
+  settings.SetInitialWindowSize(0xffffffff);
+  EXPECT_EQ(settings.initial_window_size(), 0x7fffffffu);
+}
+
+TEST(Http2SettingsTest, MaxFrameSizeLimits) {
+  Http2Settings settings;
+  settings.SetMaxFrameSize(0);
+  EXPECT_EQ(settings.max_frame_size(), 16384u);
+  settings.SetMaxFrameSize(16384);
+  EXPECT_EQ(settings.max_frame_size(), 16384u);
+  settings.SetMaxFrameSize(16385);
+  EXPECT_EQ(settings.max_frame_size(), 16385u);
+  settings.SetMaxFrameSize(16777215);
+  EXPECT_EQ(settings.max_frame_size(), 16777215u);
+  settings.SetMaxFrameSize(16777216);
+  EXPECT_EQ(settings.max_frame_size(), 16777215u);
+  settings.SetMaxFrameSize(16777217);
+  EXPECT_EQ(settings.max_frame_size(), 16777215u);
+  settings.SetMaxFrameSize(0xffffffff);
+  EXPECT_EQ(settings.max_frame_size(), 16777215u);
+}
+
+TEST(Http2SettingsTest, PreferredReceiveCryptoMessageSize) {
+  Http2Settings settings;
+  settings.SetPreferredReceiveCryptoMessageSize(0);
+  EXPECT_EQ(settings.preferred_receive_crypto_message_size(), 16384u);
+  settings.SetPreferredReceiveCryptoMessageSize(16384);
+  EXPECT_EQ(settings.preferred_receive_crypto_message_size(), 16384u);
+  settings.SetPreferredReceiveCryptoMessageSize(16385);
+  EXPECT_EQ(settings.preferred_receive_crypto_message_size(), 16385u);
+  settings.SetPreferredReceiveCryptoMessageSize(16777215);
+  EXPECT_EQ(settings.preferred_receive_crypto_message_size(), 16777215u);
+  settings.SetPreferredReceiveCryptoMessageSize(16777216);
+  EXPECT_EQ(settings.preferred_receive_crypto_message_size(), 16777216u);
+  settings.SetPreferredReceiveCryptoMessageSize(16777217);
+  EXPECT_EQ(settings.preferred_receive_crypto_message_size(), 16777217u);
+  settings.SetPreferredReceiveCryptoMessageSize(0x7fffffff);
+  EXPECT_EQ(settings.preferred_receive_crypto_message_size(), 0x7fffffffu);
+  settings.SetPreferredReceiveCryptoMessageSize(0x80000000);
+  EXPECT_EQ(settings.preferred_receive_crypto_message_size(), 0x7fffffffu);
+  settings.SetPreferredReceiveCryptoMessageSize(0xffffffff);
+  EXPECT_EQ(settings.preferred_receive_crypto_message_size(), 0x7fffffffu);
+}
+
+namespace {
+using KeyValue = std::pair<uint16_t, uint32_t>;
+using KeyValueVec = std::vector<KeyValue>;
+
+KeyValueVec Diff(const Http2Settings& a, const Http2Settings& b,
+                 bool is_first_send) {
+  KeyValueVec diffs;
+  a.Diff(is_first_send, b, [&diffs](uint16_t key, uint32_t value) {
+    diffs.emplace_back(key, value);
+  });
+  return diffs;
+}
+
+bool operator==(const KeyValue& a, const Http2SettingsFrame::Setting& b) {
+  return a.first == b.id && a.second == b.value;
+}
+
+}  // namespace
+
+TEST(Http2SettingsTest, DiffOnFreshlyInitializedSettings) {
+  const Http2Settings settings1;
+  const Http2Settings settings2;
+  EXPECT_THAT(Diff(settings1, settings2, false), ::testing::IsEmpty());
+  EXPECT_THAT(Diff(settings1, settings2, true),
+              ::testing::UnorderedElementsAre(KeyValue{4, 65535}));
+}
+
+TEST(Http2SettingsTest, DiffOnSettingsWithOneValueSet) {
+  Http2Settings settings1;
+  Http2Settings settings2;
+  settings1.SetHeaderTableSize(1);
+  EXPECT_THAT(Diff(settings1, settings2, false),
+              ::testing::UnorderedElementsAre(KeyValue{1, 1}));
+  EXPECT_THAT(
+      Diff(settings1, settings2, true),
+      ::testing::UnorderedElementsAre(KeyValue{1, 1}, KeyValue{4, 65535}));
+}
+
+TEST(Http2SettingsTest, DiffOnSettingsWithTwoValuesSet) {
+  Http2Settings settings1;
+  Http2Settings settings2;
+  settings1.SetHeaderTableSize(1);
+  settings1.SetEnablePush(false);
+  EXPECT_THAT(Diff(settings1, settings2, false),
+              ::testing::UnorderedElementsAre(KeyValue{1, 1}, KeyValue{2, 0}));
+  EXPECT_THAT(Diff(settings1, settings2, true),
+              ::testing::UnorderedElementsAre(KeyValue{1, 1}, KeyValue{2, 0},
+                                              KeyValue{4, 65535}));
+}
+
+TEST(Http2SettingsTest, DiffOnSettingsWithThreeValuesSet) {
+  Http2Settings settings1;
+  Http2Settings settings2;
+  settings1.SetHeaderTableSize(1);
+  settings1.SetEnablePush(false);
+  settings1.SetMaxConcurrentStreams(3);
+  EXPECT_THAT(Diff(settings1, settings2, false),
+              ::testing::UnorderedElementsAre(KeyValue{1, 1}, KeyValue{2, 0},
+                                              KeyValue{3, 3}));
+  EXPECT_THAT(
+      Diff(settings1, settings2, true),
+      ::testing::UnorderedElementsAre(KeyValue{1, 1}, KeyValue{2, 0},
+                                      KeyValue{3, 3}, KeyValue{4, 65535}));
+}
+
+TEST(Http2SettingsTest, DiffOnSettingsWithFourValuesSet) {
+  Http2Settings settings1;
+  Http2Settings settings2;
+  settings1.SetHeaderTableSize(1);
+  settings1.SetEnablePush(false);
+  settings1.SetMaxConcurrentStreams(3);
+  settings1.SetInitialWindowSize(4);
+  EXPECT_THAT(Diff(settings1, settings2, false),
+              ::testing::UnorderedElementsAre(KeyValue{1, 1}, KeyValue{2, 0},
+                                              KeyValue{3, 3}, KeyValue{4, 4}));
+  EXPECT_THAT(Diff(settings1, settings2, true),
+              ::testing::UnorderedElementsAre(KeyValue{1, 1}, KeyValue{2, 0},
+                                              KeyValue{3, 3}, KeyValue{4, 4}));
+}
+
+TEST(Http2SettingsTest, DiffOnSettingsWithFiveValuesSet) {
+  Http2Settings settings1;
+  Http2Settings settings2;
+  settings1.SetHeaderTableSize(1);
+  settings1.SetEnablePush(false);
+  settings1.SetMaxConcurrentStreams(3);
+  settings1.SetInitialWindowSize(4);
+  settings1.SetMaxFrameSize(50000);
+  EXPECT_THAT(Diff(settings1, settings2, false),
+              ::testing::UnorderedElementsAre(KeyValue{1, 1}, KeyValue{2, 0},
+                                              KeyValue{3, 3}, KeyValue{4, 4},
+                                              KeyValue{5, 50000}));
+  EXPECT_THAT(Diff(settings1, settings2, true),
+              ::testing::UnorderedElementsAre(KeyValue{1, 1}, KeyValue{2, 0},
+                                              KeyValue{3, 3}, KeyValue{4, 4},
+                                              KeyValue{5, 50000}));
+}
+
+TEST(Http2SettingsTest, DiffOnSettingsWithSixValuesSet) {
+  Http2Settings settings1;
+  Http2Settings settings2;
+  settings1.SetHeaderTableSize(1);
+  settings1.SetEnablePush(false);
+  settings1.SetMaxConcurrentStreams(3);
+  settings1.SetInitialWindowSize(4);
+  settings1.SetMaxFrameSize(50000);
+  settings1.SetMaxHeaderListSize(6);
+  EXPECT_THAT(Diff(settings1, settings2, false),
+              ::testing::UnorderedElementsAre(
+                  KeyValue{1, 1}, KeyValue{2, 0}, KeyValue{3, 3},
+                  KeyValue{4, 4}, KeyValue{5, 50000}, KeyValue{6, 6}));
+  EXPECT_THAT(Diff(settings1, settings2, true),
+              ::testing::UnorderedElementsAre(
+                  KeyValue{1, 1}, KeyValue{2, 0}, KeyValue{3, 3},
+                  KeyValue{4, 4}, KeyValue{5, 50000}, KeyValue{6, 6}));
+}
+
+TEST(Http2SettingsTest, DiffOnSettingsWithSevenValuesSet) {
+  Http2Settings settings1;
+  Http2Settings settings2;
+  settings1.SetHeaderTableSize(1);
+  settings1.SetEnablePush(false);
+  settings1.SetMaxConcurrentStreams(3);
+  settings1.SetInitialWindowSize(4);
+  settings1.SetMaxFrameSize(50000);
+  settings1.SetMaxHeaderListSize(6);
+  settings1.SetAllowTrueBinaryMetadata(true);
+  EXPECT_THAT(
+      Diff(settings1, settings2, false),
+      ::testing::UnorderedElementsAre(
+          KeyValue{1, 1}, KeyValue{2, 0}, KeyValue{3, 3}, KeyValue{4, 4},
+          KeyValue{5, 50000}, KeyValue{6, 6}, KeyValue{65027, 1}));
+  EXPECT_THAT(
+      Diff(settings1, settings2, true),
+      ::testing::UnorderedElementsAre(
+          KeyValue{1, 1}, KeyValue{2, 0}, KeyValue{3, 3}, KeyValue{4, 4},
+          KeyValue{5, 50000}, KeyValue{6, 6}, KeyValue{65027, 1}));
+}
+
+TEST(Http2SettingsTest, DiffOnSettingsWithEightValuesSet) {
+  Http2Settings settings1;
+  Http2Settings settings2;
+  settings1.SetHeaderTableSize(1);
+  settings1.SetEnablePush(false);
+  settings1.SetMaxConcurrentStreams(3);
+  settings1.SetInitialWindowSize(4);
+  settings1.SetMaxFrameSize(50000);
+  settings1.SetMaxHeaderListSize(6);
+  settings1.SetAllowTrueBinaryMetadata(true);
+  settings1.SetPreferredReceiveCryptoMessageSize(77777);
+  EXPECT_THAT(Diff(settings1, settings2, false),
+              ::testing::UnorderedElementsAre(
+                  KeyValue{1, 1}, KeyValue{2, 0}, KeyValue{3, 3},
+                  KeyValue{4, 4}, KeyValue{5, 50000}, KeyValue{6, 6},
+                  KeyValue{65027, 1}, KeyValue{65028, 77777}));
+  EXPECT_THAT(Diff(settings1, settings2, true),
+              ::testing::UnorderedElementsAre(
+                  KeyValue{1, 1}, KeyValue{2, 0}, KeyValue{3, 3},
+                  KeyValue{4, 4}, KeyValue{5, 50000}, KeyValue{6, 6},
+                  KeyValue{65027, 1}, KeyValue{65028, 77777}));
+}
+
+TEST(Http2SettingsTest, ChangingHeaderTableSizeChangesEquality) {
+  Http2Settings settings1;
+  Http2Settings settings2;
+  settings1.SetHeaderTableSize(1);
+  EXPECT_NE(settings1, settings2);
+  settings2.SetHeaderTableSize(1);
+  EXPECT_EQ(settings1, settings2);
+  settings2.SetHeaderTableSize(2);
+  EXPECT_NE(settings1, settings2);
+}
+
+TEST(Http2SettingsTest, ChangingEnablePushChangesEquality) {
+  Http2Settings settings1;
+  Http2Settings settings2;
+  settings1.SetEnablePush(false);
+  EXPECT_NE(settings1, settings2);
+  settings2.SetEnablePush(false);
+  EXPECT_EQ(settings1, settings2);
+  settings2.SetEnablePush(true);
+  EXPECT_NE(settings1, settings2);
+}
+
+TEST(Http2SettingsTest, ChangingMaxConcurrentStreamsChangesEquality) {
+  Http2Settings settings1;
+  Http2Settings settings2;
+  settings1.SetMaxConcurrentStreams(1);
+  EXPECT_NE(settings1, settings2);
+  settings2.SetMaxConcurrentStreams(1);
+  EXPECT_EQ(settings1, settings2);
+  settings2.SetMaxConcurrentStreams(2);
+  EXPECT_NE(settings1, settings2);
+}
+
+TEST(Http2SettingsTest, ChangingInitialWindowSizeChangesEquality) {
+  Http2Settings settings1;
+  Http2Settings settings2;
+  settings1.SetInitialWindowSize(1);
+  EXPECT_NE(settings1, settings2);
+  settings2.SetInitialWindowSize(1);
+  EXPECT_EQ(settings1, settings2);
+  settings2.SetInitialWindowSize(2);
+  EXPECT_NE(settings1, settings2);
+}
+
+TEST(Http2SettingsTest, ChangingMaxFrameSizeChangesEquality) {
+  Http2Settings settings1;
+  Http2Settings settings2;
+  settings1.SetMaxFrameSize(100000);
+  EXPECT_NE(settings1, settings2);
+  settings2.SetMaxFrameSize(100000);
+  EXPECT_EQ(settings1, settings2);
+  settings2.SetMaxFrameSize(200000);
+  EXPECT_NE(settings1, settings2);
+}
+
+TEST(Http2SettingsTest, ChangingMaxHeaderListSizeChangesEquality) {
+  Http2Settings settings1;
+  Http2Settings settings2;
+  settings1.SetMaxHeaderListSize(1);
+  EXPECT_NE(settings1, settings2);
+  settings2.SetMaxHeaderListSize(1);
+  EXPECT_EQ(settings1, settings2);
+  settings2.SetMaxHeaderListSize(2);
+  EXPECT_NE(settings1, settings2);
+}
+
+TEST(Http2SettingsTest, ChangingAllowTrueBinaryMetadataChangesEquality) {
+  Http2Settings settings1;
+  Http2Settings settings2;
+  settings1.SetAllowTrueBinaryMetadata(true);
+  EXPECT_NE(settings1, settings2);
+  settings2.SetAllowTrueBinaryMetadata(true);
+  EXPECT_EQ(settings1, settings2);
+  settings2.SetAllowTrueBinaryMetadata(false);
+  EXPECT_NE(settings1, settings2);
+}
+
+TEST(Http2SettingsTest,
+     ChangingPreferredReceiveCryptoMessageSizeChangesEquality) {
+  Http2Settings settings1;
+  Http2Settings settings2;
+  settings1.SetPreferredReceiveCryptoMessageSize(100000);
+  EXPECT_NE(settings1, settings2);
+  settings2.SetPreferredReceiveCryptoMessageSize(100000);
+  EXPECT_EQ(settings1, settings2);
+  settings2.SetPreferredReceiveCryptoMessageSize(200000);
+  EXPECT_NE(settings1, settings2);
+}
+
+TEST(Http2SettingsTest, WireIdToNameWorks) {
+  EXPECT_EQ(Http2Settings::WireIdToName(1), "HEADER_TABLE_SIZE");
+  EXPECT_EQ(Http2Settings::WireIdToName(2), "ENABLE_PUSH");
+  EXPECT_EQ(Http2Settings::WireIdToName(3), "MAX_CONCURRENT_STREAMS");
+  EXPECT_EQ(Http2Settings::WireIdToName(4), "INITIAL_WINDOW_SIZE");
+  EXPECT_EQ(Http2Settings::WireIdToName(5), "MAX_FRAME_SIZE");
+  EXPECT_EQ(Http2Settings::WireIdToName(6), "MAX_HEADER_LIST_SIZE");
+  EXPECT_EQ(Http2Settings::WireIdToName(65027),
+            "GRPC_ALLOW_TRUE_BINARY_METADATA");
+  EXPECT_EQ(Http2Settings::WireIdToName(65028),
+            "GRPC_PREFERRED_RECEIVE_MESSAGE_SIZE");
+  EXPECT_EQ(Http2Settings::WireIdToName(65029), "UNKNOWN (65029)");
+}
+
+TEST(Http2SettingsTest, ApplyHeaderTableSizeWorks) {
+  Http2Settings settings;
+  EXPECT_EQ(settings.Apply(1, 1), GRPC_HTTP2_NO_ERROR);
+  EXPECT_EQ(settings.header_table_size(), 1u);
+  EXPECT_EQ(settings.Apply(1, 0x7fffffff), GRPC_HTTP2_NO_ERROR);
+  EXPECT_EQ(settings.header_table_size(), 0x7fffffffu);
+}
+
+TEST(Http2SettingsTest, ApplyEnablePushWorks) {
+  Http2Settings settings;
+  EXPECT_EQ(settings.Apply(2, 0), GRPC_HTTP2_NO_ERROR);
+  EXPECT_EQ(settings.enable_push(), false);
+  EXPECT_EQ(settings.Apply(2, 1), GRPC_HTTP2_NO_ERROR);
+  EXPECT_EQ(settings.enable_push(), true);
+  EXPECT_EQ(settings.Apply(2, 2), GRPC_HTTP2_PROTOCOL_ERROR);
+}
+
+TEST(Http2SettingsTest, ApplyMaxConcurrentStreamsWorks) {
+  Http2Settings settings;
+  EXPECT_EQ(settings.Apply(3, 1), GRPC_HTTP2_NO_ERROR);
+  EXPECT_EQ(settings.max_concurrent_streams(), 1u);
+  EXPECT_EQ(settings.Apply(3, 0x7fffffff), GRPC_HTTP2_NO_ERROR);
+  EXPECT_EQ(settings.max_concurrent_streams(), 0x7fffffffu);
+}
+
+TEST(Http2SettingsTest, ApplyInitialWindowSizeWorks) {
+  Http2Settings settings;
+  EXPECT_EQ(settings.Apply(4, 1), GRPC_HTTP2_NO_ERROR);
+  EXPECT_EQ(settings.initial_window_size(), 1u);
+  EXPECT_EQ(settings.Apply(4, 0x7fffffff), GRPC_HTTP2_NO_ERROR);
+  EXPECT_EQ(settings.initial_window_size(), 0x7fffffffu);
+}
+
+TEST(Http2SettingsTest, ApplyMaxFrameSizeWorks) {
+  Http2Settings settings;
+  EXPECT_EQ(settings.Apply(5, 16384), GRPC_HTTP2_NO_ERROR);
+  EXPECT_EQ(settings.max_frame_size(), 16384u);
+  EXPECT_EQ(settings.Apply(5, 16777215), GRPC_HTTP2_NO_ERROR);
+  EXPECT_EQ(settings.max_frame_size(), 16777215);
+  EXPECT_EQ(settings.Apply(5, 16383), GRPC_HTTP2_PROTOCOL_ERROR);
+  EXPECT_EQ(settings.Apply(5, 16777216), GRPC_HTTP2_PROTOCOL_ERROR);
+}
+
+TEST(Http2SettingsTest, ApplyMaxHeaderListSizeWorks) {
+  Http2Settings settings;
+  EXPECT_EQ(settings.Apply(6, 1), GRPC_HTTP2_NO_ERROR);
+  EXPECT_EQ(settings.max_header_list_size(), 1u);
+  EXPECT_EQ(settings.Apply(6, 0x7fffffff), GRPC_HTTP2_NO_ERROR);
+  EXPECT_EQ(settings.max_header_list_size(), 16777216);
+}
+
+TEST(Http2SettingsTest, ApplyAllowTrueBinaryMetadataWorks) {
+  Http2Settings settings;
+  EXPECT_EQ(settings.Apply(65027, 0), GRPC_HTTP2_NO_ERROR);
+  EXPECT_EQ(settings.allow_true_binary_metadata(), false);
+  EXPECT_EQ(settings.Apply(65027, 1), GRPC_HTTP2_NO_ERROR);
+  EXPECT_EQ(settings.allow_true_binary_metadata(), true);
+  EXPECT_EQ(settings.Apply(65027, 2), GRPC_HTTP2_PROTOCOL_ERROR);
+}
+
+TEST(Http2SettingsTest, ApplyPreferredReceiveCryptoMessageSizeWorks) {
+  Http2Settings settings;
+  EXPECT_EQ(settings.Apply(65028, 1), GRPC_HTTP2_NO_ERROR);
+  EXPECT_EQ(settings.preferred_receive_crypto_message_size(), 16384u);
+  EXPECT_EQ(settings.Apply(65028, 0x7fffffff), GRPC_HTTP2_NO_ERROR);
+  EXPECT_EQ(settings.preferred_receive_crypto_message_size(), 0x7fffffffu);
+  EXPECT_EQ(settings.Apply(65028, 0x80000000), GRPC_HTTP2_NO_ERROR);
+  EXPECT_EQ(settings.preferred_receive_crypto_message_size(), 0x7fffffffu);
+}
+
+namespace {
+MATCHER_P(SettingsFrame, settings, "") {
+  if (!arg.has_value()) {
+    *result_listener << "Expected a settings frame, got nothing";
+    return false;
+  }
+  if (arg->ack) {
+    *result_listener << "Expected a settings frame, got an ack";
+    return false;
+  }
+  if (arg->settings.size() != settings.size()) {
+    *result_listener << "Expected settings frame with " << settings.size()
+                     << " settings, got " << arg->settings.size();
+    return false;
+  }
+  for (size_t i = 0; i < settings.size(); i++) {
+    bool found = false;
+    for (size_t j = 0; j < arg->settings.size(); j++) {
+      if (settings[i] == arg->settings[j]) {
+        found = true;
+        break;
+      }
+    }
+    if (!found) {
+      *result_listener << "Expected settings frame with setting "
+                       << settings[i].first << " = " << settings[i].second
+                       << ", but it was not found";
+      return false;
+    }
+  }
+  return true;
+}
+}  // namespace
+
+TEST(Http2SettingsManagerTest, ImmediatelyNeedsToSend) {
+  Http2SettingsManager settings_manager;
+  EXPECT_THAT(settings_manager.MaybeSendUpdate(),
+              SettingsFrame(KeyValueVec{{4, 65535}}));
+}
+
+TEST(Http2SettingsManagerTest, SendAckWorks) {
+  Http2SettingsManager settings_manager;
+  settings_manager.mutable_local().SetInitialWindowSize(100000);
+  EXPECT_EQ(settings_manager.acked().initial_window_size(), 65535u);
+  EXPECT_THAT(settings_manager.MaybeSendUpdate(),
+              SettingsFrame(KeyValueVec{{4, 100000}}));
+  EXPECT_TRUE(settings_manager.AckLastSend());
+  EXPECT_EQ(settings_manager.acked().initial_window_size(), 100000u);
+}
+
+TEST(Http2SettingsManagerTest, AckWithoutSendFails) {
+  Http2SettingsManager settings_manager;
+  EXPECT_FALSE(settings_manager.AckLastSend());
+}
+
+TEST(Http2SettingsManagerTest, AckAfterAckFails) {
+  Http2SettingsManager settings_manager;
+  settings_manager.mutable_local().SetInitialWindowSize(100000);
+  EXPECT_THAT(settings_manager.MaybeSendUpdate(),
+              SettingsFrame(KeyValueVec{{4, 100000}}));
+  EXPECT_TRUE(settings_manager.AckLastSend());
+  EXPECT_FALSE(settings_manager.AckLastSend());
+}
+
+}  // namespace grpc_core
+
+int main(int argc, char** argv) {
+  ::testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}