util: u_memstream: add tests

Now we have a few extra methods and things are diverging a bit between
Linux and Windows. Add a few unit tests to make sure this works.

Signed-off-by: Daniel Almeida <daniel.almeida@collabora.com>
Reviewed-by: Faith Ekstrand <faith.ekstrand@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30594>

src/util/meson.build

@@ -382,6 +382,7 @@ if with_tests
     'tests/u_call_once_test.cpp',
     'tests/u_debug_stack_test.cpp',
     'tests/u_debug_test.cpp',
+    'tests/u_memstream_test.cpp',
     'tests/u_printf_test.cpp',
     'tests/u_qsort_test.cpp',
     'tests/vector_test.cpp',

src/util/tests/u_memstream_test.cpp

@@ -0,0 +1,99 @@
+// Copyright © 2024 Collabora, Ltd.
+// SPDX-License-Identifier: MIT
+
+#include <gtest/gtest.h>
+#include "memstream.h"
+
+class MemStreamTest : public ::testing::Test {
+protected:
+    struct u_memstream mem;
+    char *buffer;
+    size_t size;
+
+    MemStreamTest() : buffer(nullptr), size(0) {
+        u_memstream_open(&mem, &buffer, &size);
+    }
+
+    ~MemStreamTest() {
+        u_memstream_close(&mem);
+        free(buffer);
+    }
+
+    void resetStream() {
+        u_memstream_close(&mem);
+        free(buffer);
+        buffer = nullptr;
+        size = 0;
+        u_memstream_open(&mem, &buffer, &size);
+    }
+};
+
+TEST_F(MemStreamTest, OpenStream) {
+    EXPECT_NE(mem.f, nullptr);
+    EXPECT_EQ(size, 0);
+}
+
+TEST_F(MemStreamTest, WriteAndFlush) {
+    const char *data = "Hello, world!";
+    size_t data_len = strlen(data);
+
+    EXPECT_EQ(fwrite(data, 1, data_len, mem.f), data_len);
+    EXPECT_EQ(u_memstream_flush(&mem), 0);
+
+    EXPECT_STREQ(buffer, data);
+    EXPECT_EQ(size, data_len);
+}
+
+TEST_F(MemStreamTest, ResetStream) {
+    const char *data = "Hello, world!";
+    size_t data_len = strlen(data);
+
+    EXPECT_EQ(fwrite(data, 1, data_len, mem.f), data_len);
+    EXPECT_EQ(u_memstream_flush(&mem), 0);
+
+    EXPECT_STREQ(buffer, data);
+    EXPECT_EQ(size, data_len);
+
+    resetStream();
+
+    EXPECT_EQ(size, 0);
+}
+
+TEST_F(MemStreamTest, WriteAfterReset) {
+    const char *data1 = "Hello, world!";
+    const char *data2 = "New data";
+    size_t data1_len = strlen(data1);
+    size_t data2_len = strlen(data2);
+
+    EXPECT_EQ(fwrite(data1, 1, data1_len, mem.f), data1_len);
+    EXPECT_EQ(u_memstream_flush(&mem), 0);
+
+    EXPECT_STREQ(buffer, data1);
+    EXPECT_EQ(size, data1_len);
+
+    resetStream();
+
+    EXPECT_EQ(size, 0);
+
+    EXPECT_EQ(fwrite(data2, 1, data2_len, mem.f), data2_len);
+    EXPECT_EQ(u_memstream_flush(&mem), 0);
+
+    EXPECT_STREQ(buffer, data2);
+    EXPECT_EQ(size, data2_len);
+}
+
+TEST_F(MemStreamTest, MultipleFlushes) {
+    const char *data = "Hello, world!";
+    size_t data_len = strlen(data);
+
+    EXPECT_EQ(fwrite(data, 1, data_len, mem.f), data_len);
+    EXPECT_EQ(u_memstream_flush(&mem), 0);
+
+    EXPECT_STREQ(buffer, data);
+    EXPECT_EQ(size, data_len);
+
+    EXPECT_EQ(u_memstream_flush(&mem), 0);
+
+    EXPECT_STREQ(buffer, data);
+    EXPECT_EQ(size, data_len);
+}