Add tests for new ByteBufferWriter accessors (and fix bug)

Bug: webrtc:15665
Change-Id: Iedf39afcec52861b501b016a7abcf7b1bcfb770c
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/331060
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Reviewed-by: Sergey Sukhanov <sergeysu@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#41361}

2 files changed, 20 insertions, 2 deletions

diff --git a/rtc_base/byte_buffer.h b/rtc_base/byte_buffer.h
index 947a87b2dc..43851f2116 100644
--- a/rtc_base/byte_buffer.h
+++ b/rtc_base/byte_buffer.h
@@ -51,7 +51,9 @@ class ByteBufferWriterT {
   absl::string_view DataAsStringView() const {
     return absl::string_view(reinterpret_cast<const char*>(Data()), Length());
   }
-  char* DataAsCharPointer() const { return reinterpret_cast<char*>(Data()); }
+  const char* DataAsCharPointer() const {
+    return reinterpret_cast<const char*>(Data());
+  }
 
   // Write value to the buffer. Resizes the buffer when it is
   // neccessary.
@@ -91,7 +93,7 @@ class ByteBufferWriterT {
     WriteBytes(&last_byte, 1);
   }
   void WriteString(absl::string_view val) {
-    WriteBytes(val.data(), val.size());
+    WriteBytes(reinterpret_cast<const value_type*>(val.data()), val.size());
   }
   void WriteBytes(const value_type* val, size_t len) {
     buffer_.AppendData(val, len);
diff --git a/rtc_base/byte_buffer_unittest.cc b/rtc_base/byte_buffer_unittest.cc
index f65299e639..7d38d809f4 100644
--- a/rtc_base/byte_buffer_unittest.cc
+++ b/rtc_base/byte_buffer_unittest.cc
@@ -16,10 +16,26 @@
 
 #include "rtc_base/arraysize.h"
 #include "rtc_base/byte_order.h"
+#include "test/gmock.h"
 #include "test/gtest.h"
 
 namespace rtc {
 
+using ::testing::ElementsAre;
+
+TEST(ByteBufferTest, WriterAccessors) {
+  // To be changed into ByteBufferWriter when base type is converted.
+  ByteBufferWriterT<BufferT<uint8_t>> buffer;
+  buffer.WriteString("abc");
+  EXPECT_EQ(buffer.Length(), 3U);
+  EXPECT_THAT(buffer.DataView(), ElementsAre('a', 'b', 'c'));
+  EXPECT_EQ(absl::string_view("abc"), buffer.DataAsStringView());
+
+  buffer.WriteUInt8(0);
+  EXPECT_STREQ(buffer.DataAsCharPointer(), "abc");
+  EXPECT_STREQ(reinterpret_cast<const char*>(buffer.Data()), "abc");
+}
+
 TEST(ByteBufferTest, TestByteOrder) {
   uint16_t n16 = 1;
   uint32_t n32 = 1;