4 files changed, 214 insertions, 0 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8cd26f43..7acc5c97 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -338,6 +338,7 @@ include(CompileGTest)
 
 # The actual unit tests follow.
 #
+unit_test(toxav ring_buffer)
 unit_test(toxav rtp)
 unit_test(toxcore crypto_core)
 unit_test(toxcore util)
diff --git a/toxav/BUILD.bazel b/toxav/BUILD.bazel
index a5d49e0d..dbe57b6c 100644
--- a/toxav/BUILD.bazel
+++ b/toxav/BUILD.bazel
@@ -18,6 +18,15 @@ cc_library(
     deps = ["//c-toxcore/toxcore:ccompat"],
 )
 
+cc_test(
+    name = "ring_buffer_test",
+    srcs = ["ring_buffer_test.cc"],
+    deps = [
+        ":ring_buffer",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
 cc_library(
     name = "bwcontroller",
     srcs = ["bwcontroller.c"],
diff --git a/toxav/ring_buffer.h b/toxav/ring_buffer.h
index 036461c1..1b52cdf2 100644
--- a/toxav/ring_buffer.h
+++ b/toxav/ring_buffer.h
@@ -25,6 +25,10 @@
 #include <stdbool.h>
 #include <stdint.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /* Ring buffer */
 typedef struct RingBuffer RingBuffer;
 bool rb_full(const RingBuffer *b);
@@ -36,4 +40,8 @@ void rb_kill(RingBuffer *b);
 uint16_t rb_size(const RingBuffer *b);
 uint16_t rb_data(const RingBuffer *b, void **dest);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* RING_BUFFER_H */
diff --git a/toxav/ring_buffer_test.cc b/toxav/ring_buffer_test.cc
new file mode 100644
index 00000000..672ee2ce
--- /dev/null
+++ b/toxav/ring_buffer_test.cc
@@ -0,0 +1,196 @@
+#include "ring_buffer.h"
+
+#include <algorithm>
+#include <cassert>
+#include <vector>
+
+#include <gtest/gtest.h>
+
+namespace {
+
+template <typename T>
+class TypedRingBuffer;
+
+template <typename T>
+class TypedRingBuffer<T *> {
+ public:
+  explicit TypedRingBuffer(int size) : rb_(rb_new(size)) {}
+  ~TypedRingBuffer() { rb_kill(rb_); }
+  TypedRingBuffer(TypedRingBuffer const &) = delete;
+
+  bool full() const { return rb_full(rb_); }
+  bool empty() const { return rb_empty(rb_); }
+  T *write(T *p) { return static_cast<T *>(rb_write(rb_, p)); }
+  bool read(T **p) {
+    void *vp;
+    bool res = rb_read(rb_, &vp);
+    *p = static_cast<T *>(vp);
+    return res;
+  }
+
+  uint16_t size() const { return rb_size(rb_); }
+  uint16_t data(T **dest) const {
+    std::vector<void *> vdest(size());
+    uint16_t res = rb_data(rb_, vdest.data());
+    for (uint16_t i = 0; i < size(); i++) {
+      dest[i] = static_cast<T *>(vdest.at(i));
+    }
+    return res;
+  }
+
+  bool contains(T *p) const {
+    std::vector<T *> elts(size());
+    data(elts.data());
+    return std::find(elts.begin(), elts.end(), p) != elts.end();
+  }
+
+  bool ok() const { return rb_ != nullptr; }
+
+ private:
+  RingBuffer *rb_;
+};
+
+TEST(RingBuffer, EmptyBufferReportsEmpty) {
+  TypedRingBuffer<int *> rb(10);
+  ASSERT_TRUE(rb.ok());
+  EXPECT_TRUE(rb.empty());
+}
+
+TEST(RingBuffer, EmptyBufferReportsNotFull) {
+  TypedRingBuffer<int *> rb(10);
+  ASSERT_TRUE(rb.ok());
+  EXPECT_FALSE(rb.full());
+}
+
+TEST(RingBuffer, ZeroSizedRingBufferIsBothEmptyAndFull) {
+  TypedRingBuffer<int *> rb(0);
+  ASSERT_TRUE(rb.ok());
+  EXPECT_TRUE(rb.empty());
+  EXPECT_TRUE(rb.full());
+}
+
+TEST(RingBuffer, WritingMakesBufferNotEmpty) {
+  TypedRingBuffer<int *> rb(2);
+  ASSERT_TRUE(rb.ok());
+  int value0 = 123;
+  rb.write(&value0);
+  EXPECT_FALSE(rb.empty());
+}
+
+TEST(RingBuffer, WritingOneElementMakesBufferNotFull) {
+  TypedRingBuffer<int *> rb(2);
+  ASSERT_TRUE(rb.ok());
+  int value0 = 123;
+  rb.write(&value0);
+  EXPECT_FALSE(rb.full());
+}
+
+TEST(RingBuffer, WritingAllElementsMakesBufferFull) {
+  TypedRingBuffer<int *> rb(2);
+  ASSERT_TRUE(rb.ok());
+  int value0 = 123;
+  int value1 = 231;
+  rb.write(&value0);
+  rb.write(&value1);
+  EXPECT_TRUE(rb.full());
+}
+
+TEST(RingBuffer, ReadingElementFromFullBufferMakesItNotFull) {
+  TypedRingBuffer<int *> rb(2);
+  ASSERT_TRUE(rb.ok());
+  int value0 = 123;
+  int value1 = 231;
+  rb.write(&value0);
+  rb.write(&value1);
+  EXPECT_TRUE(rb.full());
+  int *retrieved;
+  // Reading deletes the element.
+  EXPECT_TRUE(rb.read(&retrieved));
+  EXPECT_FALSE(rb.full());
+}
+
+TEST(RingBuffer, ZeroSizeBufferCanBeWrittenToOnce) {
+  TypedRingBuffer<int *> rb(0);
+  ASSERT_TRUE(rb.ok());
+  int value0 = 123;
+  // Strange behaviour: we can write one element to a 0-size buffer.
+  EXPECT_EQ(nullptr, rb.write(&value0));
+  EXPECT_EQ(&value0, rb.write(&value0));
+  int *retrieved = nullptr;
+  // But then we can't read it.
+  EXPECT_FALSE(rb.read(&retrieved));
+  EXPECT_EQ(nullptr, retrieved);
+}
+
+TEST(RingBuffer, ReadingFromEmptyBufferFails) {
+  TypedRingBuffer<int *> rb(2);
+  ASSERT_TRUE(rb.ok());
+  int *retrieved;
+  EXPECT_FALSE(rb.read(&retrieved));
+}
+
+TEST(RingBuffer, WritingToBufferWhenFullOverwritesBeginning) {
+  TypedRingBuffer<int *> rb(2);
+  ASSERT_TRUE(rb.ok());
+  int value0 = 123;
+  int value1 = 231;
+  int value2 = 312;
+  int value3 = 432;
+  EXPECT_EQ(nullptr, rb.write(&value0));
+  EXPECT_EQ(nullptr, rb.write(&value1));
+  EXPECT_TRUE(rb.contains(&value0));
+  EXPECT_TRUE(rb.contains(&value1));
+
+  // Adding another element evicts the first element.
+  EXPECT_EQ(&value0, rb.write(&value2));
+  EXPECT_FALSE(rb.contains(&value0));
+  EXPECT_TRUE(rb.contains(&value2));
+
+  // Adding another evicts the second.
+  EXPECT_EQ(&value1, rb.write(&value3));
+  EXPECT_FALSE(rb.contains(&value1));
+  EXPECT_TRUE(rb.contains(&value3));
+}
+
+TEST(RingBuffer, SizeIsNumberOfElementsInBuffer) {
+  TypedRingBuffer<int *> rb(10);
+  ASSERT_TRUE(rb.ok());
+  int value0 = 123;
+  EXPECT_EQ(rb.size(), 0);
+  rb.write(&value0);
+  EXPECT_EQ(rb.size(), 1);
+  rb.write(&value0);
+  EXPECT_EQ(rb.size(), 2);
+  rb.write(&value0);
+  EXPECT_EQ(rb.size(), 3);
+  rb.write(&value0);
+  EXPECT_EQ(rb.size(), 4);
+
+  int *retrieved;
+  rb.read(&retrieved);
+  EXPECT_EQ(rb.size(), 3);
+  rb.read(&retrieved);
+  EXPECT_EQ(rb.size(), 2);
+  rb.read(&retrieved);
+  EXPECT_EQ(rb.size(), 1);
+  rb.read(&retrieved);
+  EXPECT_EQ(rb.size(), 0);
+}
+
+TEST(RingBuffer, SizeIsLimitedByMaxSize) {
+  TypedRingBuffer<int *> rb(4);
+  ASSERT_TRUE(rb.ok());
+  int value0 = 123;
+  rb.write(&value0);
+  rb.write(&value0);
+  rb.write(&value0);
+  rb.write(&value0);
+  EXPECT_EQ(rb.size(), 4);
+
+  // Add one more.
+  rb.write(&value0);
+  // Still size is 4.
+  EXPECT_EQ(rb.size(), 4);
+}
+
+}  // namespace