SDL/test/testautomation_audio.c

/**
 * Original code: automated SDL audio test written by Edgar Simo "bobbens"
 * New/updated tests: aschiffler at ferzkopp dot net
 */

/* quiet windows compiler warnings */
#if defined(_MSC_VER) && !defined(_CRT_SECURE_NO_WARNINGS)
#define _CRT_SECURE_NO_WARNINGS
#endif

#include <math.h>
#include <stdio.h>
#include <string.h>

#include "SDL.h"
#include "SDL_test.h"

/* ================= Test Case Implementation ================== */

/* Fixture */

void _audioSetUp(void *arg)
{
    /* Start SDL audio subsystem */
    int ret = SDL_InitSubSystem(SDL_INIT_AUDIO);
    SDLTest_AssertPass("Call to SDL_InitSubSystem(SDL_INIT_AUDIO)");
    SDLTest_AssertCheck(ret == 0, "Check result from SDL_InitSubSystem(SDL_INIT_AUDIO)");
    if (ret != 0) {
        SDLTest_LogError("%s", SDL_GetError());
    }
}

void _audioTearDown(void *arg)
{
    /* Remove a possibly created file from SDL disk writer audio driver; ignore errors */
    (void)remove("sdlaudio.raw");

    SDLTest_AssertPass("Cleanup of test files completed");
}

/* Global counter for callback invocation */
int _audio_testCallbackCounter;

/* Global accumulator for total callback length */
int _audio_testCallbackLength;

/* Test callback function */
void SDLCALL _audio_testCallback(void *userdata, Uint8 *stream, int len)
{
    /* track that callback was called */
    _audio_testCallbackCounter++;
    _audio_testCallbackLength += len;
}

/* Test case functions */

/**
 * \brief Stop and restart audio subsystem
 *
 * \sa https://wiki.libsdl.org/SDL_QuitSubSystem
 * \sa https://wiki.libsdl.org/SDL_InitSubSystem
 */
int audio_quitInitAudioSubSystem()
{
    /* Stop SDL audio subsystem */
    SDL_QuitSubSystem(SDL_INIT_AUDIO);
    SDLTest_AssertPass("Call to SDL_QuitSubSystem(SDL_INIT_AUDIO)");

    /* Restart audio again */
    _audioSetUp(NULL);

    return TEST_COMPLETED;
}

/**
 * \brief Start and stop audio directly
 *
 * \sa https://wiki.libsdl.org/SDL_InitAudio
 * \sa https://wiki.libsdl.org/SDL_QuitAudio
 */
int audio_initQuitAudio()
{
    int result;
    int i, iMax;
    const char *audioDriver;

    /* Stop SDL audio subsystem */
    SDL_QuitSubSystem(SDL_INIT_AUDIO);
    SDLTest_AssertPass("Call to SDL_QuitSubSystem(SDL_INIT_AUDIO)");

    /* Loop over all available audio drivers */
    iMax = SDL_GetNumAudioDrivers();
    SDLTest_AssertPass("Call to SDL_GetNumAudioDrivers()");
    SDLTest_AssertCheck(iMax > 0, "Validate number of audio drivers; expected: >0 got: %d", iMax);
    for (i = 0; i < iMax; i++) {
        audioDriver = SDL_GetAudioDriver(i);
        SDLTest_AssertPass("Call to SDL_GetAudioDriver(%d)", i);
        SDLTest_Assert(audioDriver != NULL, "Audio driver name is not NULL");
        SDLTest_AssertCheck(audioDriver[0] != '\0', "Audio driver name is not empty; got: %s", audioDriver); /* NOLINT(clang-analyzer-core.NullDereference): Checked for NULL above */

        /* Call Init */
        result = SDL_AudioInit(audioDriver);
        SDLTest_AssertPass("Call to SDL_AudioInit('%s')", audioDriver);
        SDLTest_AssertCheck(result == 0, "Validate result value; expected: 0 got: %d", result);

        /* Call Quit */
        SDL_AudioQuit();
        SDLTest_AssertPass("Call to SDL_AudioQuit()");
    }

    /* NULL driver specification */
    audioDriver = NULL;

    /* Call Init */
    result = SDL_AudioInit(audioDriver);
    SDLTest_AssertPass("Call to SDL_AudioInit(NULL)");
    SDLTest_AssertCheck(result == 0, "Validate result value; expected: 0 got: %d", result);

    /* Call Quit */
    SDL_AudioQuit();
    SDLTest_AssertPass("Call to SDL_AudioQuit()");

    /* Restart audio again */
    _audioSetUp(NULL);

    return TEST_COMPLETED;
}

/**
 * \brief Start, open, close and stop audio
 *
 * \sa https://wiki.libsdl.org/SDL_InitAudio
 * \sa https://wiki.libsdl.org/SDL_OpenAudio
 * \sa https://wiki.libsdl.org/SDL_CloseAudio
 * \sa https://wiki.libsdl.org/SDL_QuitAudio
 */
int audio_initOpenCloseQuitAudio()
{
    int result, expectedResult;
    int i, iMax, j, k;
    const char *audioDriver;
    SDL_AudioSpec desired;

    /* Stop SDL audio subsystem */
    SDL_QuitSubSystem(SDL_INIT_AUDIO);
    SDLTest_AssertPass("Call to SDL_QuitSubSystem(SDL_INIT_AUDIO)");

    /* Loop over all available audio drivers */
    iMax = SDL_GetNumAudioDrivers();
    SDLTest_AssertPass("Call to SDL_GetNumAudioDrivers()");
    SDLTest_AssertCheck(iMax > 0, "Validate number of audio drivers; expected: >0 got: %d", iMax);
    for (i = 0; i < iMax; i++) {
        audioDriver = SDL_GetAudioDriver(i);
        SDLTest_AssertPass("Call to SDL_GetAudioDriver(%d)", i);
        SDLTest_Assert(audioDriver != NULL, "Audio driver name is not NULL");
        SDLTest_AssertCheck(audioDriver[0] != '\0', "Audio driver name is not empty; got: %s", audioDriver); /* NOLINT(clang-analyzer-core.NullDereference): Checked for NULL above */

        /* Change specs */
        for (j = 0; j < 2; j++) {

            /* Call Init */
            result = SDL_AudioInit(audioDriver);
            SDLTest_AssertPass("Call to SDL_AudioInit('%s')", audioDriver);
            SDLTest_AssertCheck(result == 0, "Validate result value; expected: 0 got: %d", result);

            /* Set spec */
            SDL_memset(&desired, 0, sizeof(desired));
            switch (j) {
            case 0:
                /* Set standard desired spec */
                desired.freq = 22050;
                desired.format = AUDIO_S16SYS;
                desired.channels = 2;
                desired.samples = 4096;
                desired.callback = _audio_testCallback;
                desired.userdata = NULL;

            case 1:
                /* Set custom desired spec */
                desired.freq = 48000;
                desired.format = AUDIO_F32SYS;
                desired.channels = 2;
                desired.samples = 2048;
                desired.callback = _audio_testCallback;
                desired.userdata = NULL;
                break;
            }

            /* Call Open (maybe multiple times) */
            for (k = 0; k <= j; k++) {
                result = SDL_OpenAudio(&desired, NULL);
                SDLTest_AssertPass("Call to SDL_OpenAudio(desired_spec_%d, NULL), call %d", j, k + 1);
                expectedResult = (k == 0) ? 0 : -1;
                SDLTest_AssertCheck(result == expectedResult, "Verify return value; expected: %d, got: %d", expectedResult, result);
            }

            /* Call Close (maybe multiple times) */
            for (k = 0; k <= j; k++) {
                SDL_CloseAudio();
                SDLTest_AssertPass("Call to SDL_CloseAudio(), call %d", k + 1);
            }

            /* Call Quit (maybe multiple times) */
            for (k = 0; k <= j; k++) {
                SDL_AudioQuit();
                SDLTest_AssertPass("Call to SDL_AudioQuit(), call %d", k + 1);
            }

        } /* spec loop */
    }     /* driver loop */

    /* Restart audio again */
    _audioSetUp(NULL);

    return TEST_COMPLETED;
}

/**
 * \brief Pause and unpause audio
 *
 * \sa https://wiki.libsdl.org/SDL_PauseAudio
 */
int audio_pauseUnpauseAudio()
{
    int result;
    int i, iMax, j, k, l;
    int totalDelay;
    int pause_on;
    int originalCounter;
    const char *audioDriver;
    SDL_AudioSpec desired;

    /* Stop SDL audio subsystem */
    SDL_QuitSubSystem(SDL_INIT_AUDIO);
    SDLTest_AssertPass("Call to SDL_QuitSubSystem(SDL_INIT_AUDIO)");

    /* Loop over all available audio drivers */
    iMax = SDL_GetNumAudioDrivers();
    SDLTest_AssertPass("Call to SDL_GetNumAudioDrivers()");
    SDLTest_AssertCheck(iMax > 0, "Validate number of audio drivers; expected: >0 got: %d", iMax);
    for (i = 0; i < iMax; i++) {
        audioDriver = SDL_GetAudioDriver(i);
        SDLTest_AssertPass("Call to SDL_GetAudioDriver(%d)", i);
        SDLTest_Assert(audioDriver != NULL, "Audio driver name is not NULL");
        SDLTest_AssertCheck(audioDriver[0] != '\0', "Audio driver name is not empty; got: %s", audioDriver); /* NOLINT(clang-analyzer-core.NullDereference): Checked for NULL above */

        /* Change specs */
        for (j = 0; j < 2; j++) {

            /* Call Init */
            result = SDL_AudioInit(audioDriver);
            SDLTest_AssertPass("Call to SDL_AudioInit('%s')", audioDriver);
            SDLTest_AssertCheck(result == 0, "Validate result value; expected: 0 got: %d", result);

            /* Set spec */
            SDL_memset(&desired, 0, sizeof(desired));
            switch (j) {
            case 0:
                /* Set standard desired spec */
                desired.freq = 22050;
                desired.format = AUDIO_S16SYS;
                desired.channels = 2;
                desired.samples = 4096;
                desired.callback = _audio_testCallback;
                desired.userdata = NULL;

            case 1:
                /* Set custom desired spec */
                desired.freq = 48000;
                desired.format = AUDIO_F32SYS;
                desired.channels = 2;
                desired.samples = 2048;
                desired.callback = _audio_testCallback;
                desired.userdata = NULL;
                break;
            }

            /* Call Open */
            result = SDL_OpenAudio(&desired, NULL);
            SDLTest_AssertPass("Call to SDL_OpenAudio(desired_spec_%d, NULL)", j);
            SDLTest_AssertCheck(result == 0, "Verify return value; expected: 0 got: %d", result);

            /* Start and stop audio multiple times */
            for (l = 0; l < 3; l++) {
                SDLTest_Log("Pause/Unpause iteration: %d", l + 1);

                /* Reset callback counters */
                _audio_testCallbackCounter = 0;
                _audio_testCallbackLength = 0;

                /* Un-pause audio to start playing (maybe multiple times) */
                pause_on = 0;
                for (k = 0; k <= j; k++) {
                    SDL_PauseAudio(pause_on);
                    SDLTest_AssertPass("Call to SDL_PauseAudio(%d), call %d", pause_on, k + 1);
                }

                /* Wait for callback */
                totalDelay = 0;
                do {
                    SDL_Delay(10);
                    totalDelay += 10;
                } while (_audio_testCallbackCounter == 0 && totalDelay < 1000);
                SDLTest_AssertCheck(_audio_testCallbackCounter > 0, "Verify callback counter; expected: >0 got: %d", _audio_testCallbackCounter);
                SDLTest_AssertCheck(_audio_testCallbackLength > 0, "Verify callback length; expected: >0 got: %d", _audio_testCallbackLength);

                /* Pause audio to stop playing (maybe multiple times) */
                for (k = 0; k <= j; k++) {
                    pause_on = (k == 0) ? 1 : SDLTest_RandomIntegerInRange(99, 9999);
                    SDL_PauseAudio(pause_on);
                    SDLTest_AssertPass("Call to SDL_PauseAudio(%d), call %d", pause_on, k + 1);
                }

                /* Ensure callback is not called again */
                originalCounter = _audio_testCallbackCounter;
                SDL_Delay(totalDelay + 10);
                SDLTest_AssertCheck(originalCounter == _audio_testCallbackCounter, "Verify callback counter; expected: %d, got: %d", originalCounter, _audio_testCallbackCounter);
            }

            /* Call Close */
            SDL_CloseAudio();
            SDLTest_AssertPass("Call to SDL_CloseAudio()");

            /* Call Quit */
            SDL_AudioQuit();
            SDLTest_AssertPass("Call to SDL_AudioQuit()");

        } /* spec loop */
    }     /* driver loop */

    /* Restart audio again */
    _audioSetUp(NULL);

    return TEST_COMPLETED;
}

/**
 * \brief Enumerate and name available audio devices (output and capture).
 *
 * \sa https://wiki.libsdl.org/SDL_GetNumAudioDevices
 * \sa https://wiki.libsdl.org/SDL_GetAudioDeviceName
 */
int audio_enumerateAndNameAudioDevices()
{
    int t, tt;
    int i, n, nn;
    const char *name, *nameAgain;

    /* Iterate over types: t=0 output device, t=1 input/capture device */
    for (t = 0; t < 2; t++) {

        /* Get number of devices. */
        n = SDL_GetNumAudioDevices(t);
        SDLTest_AssertPass("Call to SDL_GetNumAudioDevices(%i)", t);
        SDLTest_Log("Number of %s devices < 0, reported as %i", (t) ? "capture" : "output", n);
        SDLTest_AssertCheck(n >= 0, "Validate result is >= 0, got: %i", n);

        /* Variation of non-zero type */
        if (t == 1) {
            tt = t + SDLTest_RandomIntegerInRange(1, 10);
            nn = SDL_GetNumAudioDevices(tt);
            SDLTest_AssertCheck(n == nn, "Verify result from SDL_GetNumAudioDevices(%i), expected same number of audio devices %i, got %i", tt, n, nn);
            nn = SDL_GetNumAudioDevices(-tt);
            SDLTest_AssertCheck(n == nn, "Verify result from SDL_GetNumAudioDevices(%i), expected same number of audio devices %i, got %i", -tt, n, nn);
        }

        /* List devices. */
        if (n > 0) {
            for (i = 0; i < n; i++) {
                name = SDL_GetAudioDeviceName(i, t);
                SDLTest_AssertPass("Call to SDL_GetAudioDeviceName(%i, %i)", i, t);
                SDLTest_AssertCheck(name != NULL, "Verify result from SDL_GetAudioDeviceName(%i, %i) is not NULL", i, t);
                if (name != NULL) {
                    SDLTest_AssertCheck(name[0] != '\0', "verify result from SDL_GetAudioDeviceName(%i, %i) is not empty, got: '%s'", i, t, name);
                    if (t == 1) {
                        /* Also try non-zero type */
                        tt = t + SDLTest_RandomIntegerInRange(1, 10);
                        nameAgain = SDL_GetAudioDeviceName(i, tt);
                        SDLTest_AssertCheck(nameAgain != NULL, "Verify result from SDL_GetAudioDeviceName(%i, %i) is not NULL", i, tt);
                        if (nameAgain != NULL) {
                            SDLTest_AssertCheck(nameAgain[0] != '\0', "Verify result from SDL_GetAudioDeviceName(%i, %i) is not empty, got: '%s'", i, tt, nameAgain);
                            SDLTest_AssertCheck(SDL_strcmp(name, nameAgain) == 0,
                                                "Verify SDL_GetAudioDeviceName(%i, %i) and SDL_GetAudioDeviceName(%i %i) return the same string",
                                                i, t, i, tt);
                        }
                    }
                }
            }
        }
    }

    return TEST_COMPLETED;
}

/**
 * \brief Negative tests around enumeration and naming of audio devices.
 *
 * \sa https://wiki.libsdl.org/SDL_GetNumAudioDevices
 * \sa https://wiki.libsdl.org/SDL_GetAudioDeviceName
 */
int audio_enumerateAndNameAudioDevicesNegativeTests()
{
    int t;
    int i, j, no, nc;
    const char *name;

    /* Get number of devices. */
    no = SDL_GetNumAudioDevices(0);
    SDLTest_AssertPass("Call to SDL_GetNumAudioDevices(0)");
    nc = SDL_GetNumAudioDevices(1);
    SDLTest_AssertPass("Call to SDL_GetNumAudioDevices(1)");

    /* Invalid device index when getting name */
    for (t = 0; t < 2; t++) {
        /* Negative device index */
        i = SDLTest_RandomIntegerInRange(-10, -1);
        name = SDL_GetAudioDeviceName(i, t);
        SDLTest_AssertPass("Call to SDL_GetAudioDeviceName(%i, %i)", i, t);
        SDLTest_AssertCheck(name == NULL, "Check SDL_GetAudioDeviceName(%i, %i) result NULL, expected NULL, got: %s", i, t, (name == NULL) ? "NULL" : name);

        /* Device index past range */
        for (j = 0; j < 3; j++) {
            i = (t) ? nc + j : no + j;
            name = SDL_GetAudioDeviceName(i, t);
            SDLTest_AssertPass("Call to SDL_GetAudioDeviceName(%i, %i)", i, t);
            SDLTest_AssertCheck(name == NULL, "Check SDL_GetAudioDeviceName(%i, %i) result, expected: NULL, got: %s", i, t, (name == NULL) ? "NULL" : name);
        }

        /* Capture index past capture range but within output range */
        if ((no > 0) && (no > nc) && (t == 1)) {
            i = no - 1;
            name = SDL_GetAudioDeviceName(i, t);
            SDLTest_AssertPass("Call to SDL_GetAudioDeviceName(%i, %i)", i, t);
            SDLTest_AssertCheck(name == NULL, "Check SDL_GetAudioDeviceName(%i, %i) result, expected: NULL, got: %s", i, t, (name == NULL) ? "NULL" : name);
        }
    }

    return TEST_COMPLETED;
}

/**
 * \brief Checks available audio driver names.
 *
 * \sa https://wiki.libsdl.org/SDL_GetNumAudioDrivers
 * \sa https://wiki.libsdl.org/SDL_GetAudioDriver
 */
int audio_printAudioDrivers()
{
    int i, n;
    const char *name;

    /* Get number of drivers */
    n = SDL_GetNumAudioDrivers();
    SDLTest_AssertPass("Call to SDL_GetNumAudioDrivers()");
    SDLTest_AssertCheck(n >= 0, "Verify number of audio drivers >= 0, got: %i", n);

    /* List drivers. */
    if (n > 0) {
        for (i = 0; i < n; i++) {
            name = SDL_GetAudioDriver(i);
            SDLTest_AssertPass("Call to SDL_GetAudioDriver(%i)", i);
            SDLTest_AssertCheck(name != NULL, "Verify returned name is not NULL");
            if (name != NULL) {
                SDLTest_AssertCheck(name[0] != '\0', "Verify returned name is not empty, got: '%s'", name);
            }
        }
    }

    return TEST_COMPLETED;
}

/**
 * \brief Checks current audio driver name with initialized audio.
 *
 * \sa https://wiki.libsdl.org/SDL_GetCurrentAudioDriver
 */
int audio_printCurrentAudioDriver()
{
    /* Check current audio driver */
    const char *name = SDL_GetCurrentAudioDriver();
    SDLTest_AssertPass("Call to SDL_GetCurrentAudioDriver()");
    SDLTest_AssertCheck(name != NULL, "Verify returned name is not NULL");
    if (name != NULL) {
        SDLTest_AssertCheck(name[0] != '\0', "Verify returned name is not empty, got: '%s'", name);
    }

    return TEST_COMPLETED;
}

/* Definition of all formats, channels, and frequencies used to test audio conversions */
const int _numAudioFormats = 18;
SDL_AudioFormat _audioFormats[] = { AUDIO_S8, AUDIO_U8, AUDIO_S16LSB, AUDIO_S16MSB, AUDIO_S16SYS, AUDIO_S16, AUDIO_U16LSB,
                                    AUDIO_U16MSB, AUDIO_U16SYS, AUDIO_U16, AUDIO_S32LSB, AUDIO_S32MSB, AUDIO_S32SYS, AUDIO_S32,
                                    AUDIO_F32LSB, AUDIO_F32MSB, AUDIO_F32SYS, AUDIO_F32 };
const char *_audioFormatsVerbose[] = { "AUDIO_S8", "AUDIO_U8", "AUDIO_S16LSB", "AUDIO_S16MSB", "AUDIO_S16SYS", "AUDIO_S16", "AUDIO_U16LSB",
                                       "AUDIO_U16MSB", "AUDIO_U16SYS", "AUDIO_U16", "AUDIO_S32LSB", "AUDIO_S32MSB", "AUDIO_S32SYS", "AUDIO_S32",
                                       "AUDIO_F32LSB", "AUDIO_F32MSB", "AUDIO_F32SYS", "AUDIO_F32" };
const int _numAudioChannels = 4;
Uint8 _audioChannels[] = { 1, 2, 4, 6 };
const int _numAudioFrequencies = 4;
int _audioFrequencies[] = { 11025, 22050, 44100, 48000 };

/**
 * \brief Builds various audio conversion structures
 *
 * \sa https://wiki.libsdl.org/SDL_BuildAudioCVT
 */
int audio_buildAudioCVT()
{
    int result;
    SDL_AudioCVT cvt;
    SDL_AudioSpec spec1;
    SDL_AudioSpec spec2;
    int i, ii, j, jj, k, kk;

    /* No conversion needed */
    spec1.format = AUDIO_S16LSB;
    spec1.channels = 2;
    spec1.freq = 22050;
    result = SDL_BuildAudioCVT(&cvt, spec1.format, spec1.channels, spec1.freq,
                               spec1.format, spec1.channels, spec1.freq);
    SDLTest_AssertPass("Call to SDL_BuildAudioCVT(spec1 ==> spec1)");
    SDLTest_AssertCheck(result == 0, "Verify result value; expected: 0, got: %i", result);

    /* Typical conversion */
    spec1.format = AUDIO_S8;
    spec1.channels = 1;
    spec1.freq = 22050;
    spec2.format = AUDIO_S16LSB;
    spec2.channels = 2;
    spec2.freq = 44100;
    result = SDL_BuildAudioCVT(&cvt, spec1.format, spec1.channels, spec1.freq,
                               spec2.format, spec2.channels, spec2.freq);
    SDLTest_AssertPass("Call to SDL_BuildAudioCVT(spec1 ==> spec2)");
    SDLTest_AssertCheck(result == 1, "Verify result value; expected: 1, got: %i", result);

    /* All source conversions with random conversion targets, allow 'null' conversions */
    for (i = 0; i < _numAudioFormats; i++) {
        for (j = 0; j < _numAudioChannels; j++) {
            for (k = 0; k < _numAudioFrequencies; k++) {
                spec1.format = _audioFormats[i];
                spec1.channels = _audioChannels[j];
                spec1.freq = _audioFrequencies[k];
                ii = SDLTest_RandomIntegerInRange(0, _numAudioFormats - 1);
                jj = SDLTest_RandomIntegerInRange(0, _numAudioChannels - 1);
                kk = SDLTest_RandomIntegerInRange(0, _numAudioFrequencies - 1);
                spec2.format = _audioFormats[ii];
                spec2.channels = _audioChannels[jj];
                spec2.freq = _audioFrequencies[kk];
                result = SDL_BuildAudioCVT(&cvt, spec1.format, spec1.channels, spec1.freq,
                                           spec2.format, spec2.channels, spec2.freq);
                SDLTest_AssertPass("Call to SDL_BuildAudioCVT(format[%i]=%s(%i),channels[%i]=%i,freq[%i]=%i ==> format[%i]=%s(%i),channels[%i]=%i,freq[%i]=%i)",
                                   i, _audioFormatsVerbose[i], spec1.format, j, spec1.channels, k, spec1.freq, ii, _audioFormatsVerbose[ii], spec2.format, jj, spec2.channels, kk, spec2.freq);
                SDLTest_AssertCheck(result == 0 || result == 1, "Verify result value; expected: 0 or 1, got: %i", result);
                if (result < 0) {
                    SDLTest_LogError("%s", SDL_GetError());
                } else {
                    SDLTest_AssertCheck(cvt.len_mult > 0, "Verify that cvt.len_mult value; expected: >0, got: %i", cvt.len_mult);
                }
            }
        }
    }

    return TEST_COMPLETED;
}

/**
 * \brief Checkes calls with invalid input to SDL_BuildAudioCVT
 *
 * \sa https://wiki.libsdl.org/SDL_BuildAudioCVT
 */
int audio_buildAudioCVTNegative()
{
    const char *expectedError = "Parameter 'cvt' is invalid";
    const char *error;
    int result;
    SDL_AudioCVT cvt;
    SDL_AudioSpec spec1;
    SDL_AudioSpec spec2;
    int i;
    char message[256];

    /* Valid format */
    spec1.format = AUDIO_S8;
    spec1.channels = 1;
    spec1.freq = 22050;
    spec2.format = AUDIO_S16LSB;
    spec2.channels = 2;
    spec2.freq = 44100;

    SDL_ClearError();
    SDLTest_AssertPass("Call to SDL_ClearError()");

    /* NULL input for CVT buffer */
    result = SDL_BuildAudioCVT((SDL_AudioCVT *)NULL, spec1.format, spec1.channels, spec1.freq,
                               spec2.format, spec2.channels, spec2.freq);
    SDLTest_AssertPass("Call to SDL_BuildAudioCVT(NULL,...)");
    SDLTest_AssertCheck(result == -1, "Verify result value; expected: -1, got: %i", result);
    error = SDL_GetError();
    SDLTest_AssertPass("Call to SDL_GetError()");
    SDLTest_AssertCheck(error != NULL, "Validate that error message was not NULL");
    if (error != NULL) {
        SDLTest_AssertCheck(SDL_strcmp(error, expectedError) == 0,
                            "Validate error message, expected: '%s', got: '%s'", expectedError, error);
    }

    /* Invalid conversions */
    for (i = 1; i < 64; i++) {
        /* Valid format to start with */
        spec1.format = AUDIO_S8;
        spec1.channels = 1;
        spec1.freq = 22050;
        spec2.format = AUDIO_S16LSB;
        spec2.channels = 2;
        spec2.freq = 44100;

        SDL_ClearError();
        SDLTest_AssertPass("Call to SDL_ClearError()");

        /* Set various invalid format inputs */
        SDL_strlcpy(message, "Invalid: ", 256);
        if (i & 1) {
            SDL_strlcat(message, " spec1.format", 256);
            spec1.format = 0;
        }
        if (i & 2) {
            SDL_strlcat(message, " spec1.channels", 256);
            spec1.channels = 0;
        }
        if (i & 4) {
            SDL_strlcat(message, " spec1.freq", 256);
            spec1.freq = 0;
        }
        if (i & 8) {
            SDL_strlcat(message, " spec2.format", 256);
            spec2.format = 0;
        }
        if (i & 16) {
            SDL_strlcat(message, " spec2.channels", 256);
            spec2.channels = 0;
        }
        if (i & 32) {
            SDL_strlcat(message, " spec2.freq", 256);
            spec2.freq = 0;
        }
        SDLTest_Log("%s", message);
        result = SDL_BuildAudioCVT(&cvt, spec1.format, spec1.channels, spec1.freq,
                                   spec2.format, spec2.channels, spec2.freq);
        SDLTest_AssertPass("Call to SDL_BuildAudioCVT(spec1 ==> spec2)");
        SDLTest_AssertCheck(result == -1, "Verify result value; expected: -1, got: %i", result);
        error = SDL_GetError();
        SDLTest_AssertPass("Call to SDL_GetError()");
        SDLTest_AssertCheck(error != NULL && error[0] != '\0', "Validate that error message was not NULL or empty");
    }

    SDL_ClearError();
    SDLTest_AssertPass("Call to SDL_ClearError()");

    return TEST_COMPLETED;
}

/**
 * \brief Checks current audio status.
 *
 * \sa https://wiki.libsdl.org/SDL_GetAudioStatus
 */
int audio_getAudioStatus()
{
    SDL_AudioStatus result;

    /* Check current audio status */
    result = SDL_GetAudioStatus();
    SDLTest_AssertPass("Call to SDL_GetAudioStatus()");
    SDLTest_AssertCheck(result == SDL_AUDIO_STOPPED || result == SDL_AUDIO_PLAYING || result == SDL_AUDIO_PAUSED,
                        "Verify returned value; expected: STOPPED (%i) | PLAYING (%i) | PAUSED (%i), got: %i",
                        SDL_AUDIO_STOPPED, SDL_AUDIO_PLAYING, SDL_AUDIO_PAUSED, result);

    return TEST_COMPLETED;
}

/**
 * \brief Opens, checks current audio status, and closes a device.
 *
 * \sa https://wiki.libsdl.org/SDL_GetAudioStatus
 */
int audio_openCloseAndGetAudioStatus()
{
    SDL_AudioStatus result;
    int i;
    int count;
    const char *device;
    SDL_AudioDeviceID id;
    SDL_AudioSpec desired, obtained;

    /* Get number of devices. */
    count = SDL_GetNumAudioDevices(0);
    SDLTest_AssertPass("Call to SDL_GetNumAudioDevices(0)");
    if (count > 0) {
        for (i = 0; i < count; i++) {
            /* Get device name */
            device = SDL_GetAudioDeviceName(i, 0);
            SDLTest_AssertPass("SDL_GetAudioDeviceName(%i,0)", i);
            SDLTest_AssertCheck(device != NULL, "Validate device name is not NULL; got: %s", (device != NULL) ? device : "NULL");
            if (device == NULL) {
                return TEST_ABORTED;
            }

            /* Set standard desired spec */
            desired.freq = 22050;
            desired.format = AUDIO_S16SYS;
            desired.channels = 2;
            desired.samples = 4096;
            desired.callback = _audio_testCallback;
            desired.userdata = NULL;

            /* Open device */
            id = SDL_OpenAudioDevice(device, 0, &desired, &obtained, SDL_AUDIO_ALLOW_ANY_CHANGE);
            SDLTest_AssertPass("SDL_OpenAudioDevice('%s',...)", device);
            SDLTest_AssertCheck(id > 1, "Validate device ID; expected: >=2, got: %" SDL_PRIu32, id);
            if (id > 1) {

                /* Check device audio status */
                result = SDL_GetAudioDeviceStatus(id);
                SDLTest_AssertPass("Call to SDL_GetAudioDeviceStatus()");
                SDLTest_AssertCheck(result == SDL_AUDIO_STOPPED || result == SDL_AUDIO_PLAYING || result == SDL_AUDIO_PAUSED,
                                    "Verify returned value; expected: STOPPED (%i) | PLAYING (%i) | PAUSED (%i), got: %i",
                                    SDL_AUDIO_STOPPED, SDL_AUDIO_PLAYING, SDL_AUDIO_PAUSED, result);

                /* Close device again */
                SDL_CloseAudioDevice(id);
                SDLTest_AssertPass("Call to SDL_CloseAudioDevice()");
            }
        }
    } else {
        SDLTest_Log("No devices to test with");
    }

    return TEST_COMPLETED;
}

/**
 * \brief Locks and unlocks open audio device.
 *
 * \sa https://wiki.libsdl.org/SDL_LockAudioDevice
 * \sa https://wiki.libsdl.org/SDL_UnlockAudioDevice
 */
int audio_lockUnlockOpenAudioDevice()
{
    int i;
    int count;
    const char *device;
    SDL_AudioDeviceID id;
    SDL_AudioSpec desired, obtained;

    /* Get number of devices. */
    count = SDL_GetNumAudioDevices(0);
    SDLTest_AssertPass("Call to SDL_GetNumAudioDevices(0)");
    if (count > 0) {
        for (i = 0; i < count; i++) {
            /* Get device name */
            device = SDL_GetAudioDeviceName(i, 0);
            SDLTest_AssertPass("SDL_GetAudioDeviceName(%i,0)", i);
            SDLTest_AssertCheck(device != NULL, "Validate device name is not NULL; got: %s", (device != NULL) ? device : "NULL");
            if (device == NULL) {
                return TEST_ABORTED;
            }

            /* Set standard desired spec */
            desired.freq = 22050;
            desired.format = AUDIO_S16SYS;
            desired.channels = 2;
            desired.samples = 4096;
            desired.callback = _audio_testCallback;
            desired.userdata = NULL;

            /* Open device */
            id = SDL_OpenAudioDevice(device, 0, &desired, &obtained, SDL_AUDIO_ALLOW_ANY_CHANGE);
            SDLTest_AssertPass("SDL_OpenAudioDevice('%s',...)", device);
            SDLTest_AssertCheck(id > 1, "Validate device ID; expected: >=2, got: %" SDL_PRIu32, id);
            if (id > 1) {
                /* Lock to protect callback */
                SDL_LockAudioDevice(id);
                SDLTest_AssertPass("SDL_LockAudioDevice(%" SDL_PRIu32 ")", id);

                /* Simulate callback processing */
                SDL_Delay(10);
                SDLTest_Log("Simulate callback processing - delay");

                /* Unlock again */
                SDL_UnlockAudioDevice(id);
                SDLTest_AssertPass("SDL_UnlockAudioDevice(%" SDL_PRIu32 ")", id);

                /* Close device again */
                SDL_CloseAudioDevice(id);
                SDLTest_AssertPass("Call to SDL_CloseAudioDevice()");
            }
        }
    } else {
        SDLTest_Log("No devices to test with");
    }

    return TEST_COMPLETED;
}

/**
 * \brief Convert audio using various conversion structures
 *
 * \sa https://wiki.libsdl.org/SDL_BuildAudioCVT
 * \sa https://wiki.libsdl.org/SDL_ConvertAudio
 */
int audio_convertAudio()
{
    int result;
    SDL_AudioCVT cvt;
    SDL_AudioSpec spec1;
    SDL_AudioSpec spec2;
    int c;
    char message[128];
    int i, ii, j, jj, k, kk, l, ll;

    /* Iterate over bitmask that determines which parameters are modified in the conversion */
    for (c = 1; c < 8; c++) {
        SDL_strlcpy(message, "Changing:", 128);
        if (c & 1) {
            SDL_strlcat(message, " Format", 128);
        }
        if (c & 2) {
            SDL_strlcat(message, " Channels", 128);
        }
        if (c & 4) {
            SDL_strlcat(message, " Frequencies", 128);
        }
        SDLTest_Log("%s", message);
        /* All source conversions with random conversion targets */
        for (i = 0; i < _numAudioFormats; i++) {
            for (j = 0; j < _numAudioChannels; j++) {
                for (k = 0; k < _numAudioFrequencies; k++) {
                    spec1.format = _audioFormats[i];
                    spec1.channels = _audioChannels[j];
                    spec1.freq = _audioFrequencies[k];

                    /* Ensure we have a different target format */
                    do {
                        if (c & 1) {
                            ii = SDLTest_RandomIntegerInRange(0, _numAudioFormats - 1);
                        } else {
                            ii = 1;
                        }
                        if (c & 2) {
                            jj = SDLTest_RandomIntegerInRange(0, _numAudioChannels - 1);
                        } else {
                            jj = j;
                        }
                        if (c & 4) {
                            kk = SDLTest_RandomIntegerInRange(0, _numAudioFrequencies - 1);
                        } else {
                            kk = k;
                        }
                    } while ((i == ii) && (j == jj) && (k == kk));
                    spec2.format = _audioFormats[ii];
                    spec2.channels = _audioChannels[jj];
                    spec2.freq = _audioFrequencies[kk];

                    result = SDL_BuildAudioCVT(&cvt, spec1.format, spec1.channels, spec1.freq,
                                               spec2.format, spec2.channels, spec2.freq);
                    SDLTest_AssertPass("Call to SDL_BuildAudioCVT(format[%i]=%s(%i),channels[%i]=%i,freq[%i]=%i ==> format[%i]=%s(%i),channels[%i]=%i,freq[%i]=%i)",
                                       i, _audioFormatsVerbose[i], spec1.format, j, spec1.channels, k, spec1.freq, ii, _audioFormatsVerbose[ii], spec2.format, jj, spec2.channels, kk, spec2.freq);
                    SDLTest_AssertCheck(result == 1, "Verify result value; expected: 1, got: %i", result);
                    if (result != 1) {
                        SDLTest_LogError("%s", SDL_GetError());
                    } else {
                        SDLTest_AssertCheck(cvt.len_mult > 0, "Verify that cvt.len_mult value; expected: >0, got: %i", cvt.len_mult);
                        if (cvt.len_mult < 1) {
                            return TEST_ABORTED;
                        }

                        /* Create some random data to convert */
                        l = 64;
                        ll = l * cvt.len_mult;
                        SDLTest_Log("Creating dummy sample buffer of %i length (%i bytes)", l, ll);
                        cvt.len = l;
                        cvt.buf = (Uint8 *)SDL_malloc(ll);
                        SDLTest_AssertCheck(cvt.buf != NULL, "Check data buffer to convert is not NULL");
                        if (cvt.buf == NULL) {
                            return TEST_ABORTED;
                        }

                        /* Convert the data */
                        result = SDL_ConvertAudio(&cvt);
                        SDLTest_AssertPass("Call to SDL_ConvertAudio()");
                        SDLTest_AssertCheck(result == 0, "Verify result value; expected: 0; got: %i", result);
                        SDLTest_AssertCheck(cvt.buf != NULL, "Verify conversion buffer is not NULL");
                        SDLTest_AssertCheck(cvt.len_ratio > 0.0, "Verify conversion length ratio; expected: >0; got: %f", cvt.len_ratio);

                        /* Free converted buffer */
                        SDL_free(cvt.buf);
                        cvt.buf = NULL;
                    }
                }
            }
        }
    }

    return TEST_COMPLETED;
}

/**
 * \brief Opens, checks current connected status, and closes a device.
 *
 * \sa https://wiki.libsdl.org/SDL_AudioDeviceConnected
 */
int audio_openCloseAudioDeviceConnected()
{
    int result = -1;
    int i;
    int count;
    const char *device;
    SDL_AudioDeviceID id;
    SDL_AudioSpec desired, obtained;

    /* Get number of devices. */
    count = SDL_GetNumAudioDevices(0);
    SDLTest_AssertPass("Call to SDL_GetNumAudioDevices(0)");
    if (count > 0) {
        for (i = 0; i < count; i++) {
            /* Get device name */
            device = SDL_GetAudioDeviceName(i, 0);
            SDLTest_AssertPass("SDL_GetAudioDeviceName(%i,0)", i);
            SDLTest_AssertCheck(device != NULL, "Validate device name is not NULL; got: %s", (device != NULL) ? device : "NULL");
            if (device == NULL) {
                return TEST_ABORTED;
            }

            /* Set standard desired spec */
            desired.freq = 22050;
            desired.format = AUDIO_S16SYS;
            desired.channels = 2;
            desired.samples = 4096;
            desired.callback = _audio_testCallback;
            desired.userdata = NULL;

            /* Open device */
            id = SDL_OpenAudioDevice(device, 0, &desired, &obtained, SDL_AUDIO_ALLOW_ANY_CHANGE);
            SDLTest_AssertPass("SDL_OpenAudioDevice('%s',...)", device);
            SDLTest_AssertCheck(id > 1, "Validate device ID; expected: >1, got: %" SDL_PRIu32, id);
            if (id > 1) {

/* TODO: enable test code when function is available in SDL2 */

#ifdef AUDIODEVICECONNECTED_DEFINED
                /* Get connected status */
                result = SDL_AudioDeviceConnected(id);
                SDLTest_AssertPass("Call to SDL_AudioDeviceConnected()");
#endif
                SDLTest_AssertCheck(result == 1, "Verify returned value; expected: 1; got: %i", result);

                /* Close device again */
                SDL_CloseAudioDevice(id);
                SDLTest_AssertPass("Call to SDL_CloseAudioDevice()");
            }
        }
    } else {
        SDLTest_Log("No devices to test with");
    }

    return TEST_COMPLETED;
}

static double sine_wave_sample(const Sint64 idx, const Sint64 rate, const Sint64 freq, const double phase)
{
  /* Using integer modulo to avoid precision loss caused by large floating
   * point numbers. Sint64 is needed for the large integer multiplication.
   * The integers are assumed to be non-negative so that modulo is always
   * non-negative.
   *   sin(i / rate * freq * 2 * M_PI + phase)
   * = sin(mod(i / rate * freq, 1) * 2 * M_PI + phase)
   * = sin(mod(i * freq, rate) / rate * 2 * M_PI + phase) */
  return SDL_sin(((double) (idx * freq % rate)) / ((double) rate) * (M_PI * 2) + phase);
}

/**
 * \brief Check signal-to-noise ratio and maximum error of audio resampling.
 *
 * \sa https://wiki.libsdl.org/SDL_BuildAudioCVT
 * \sa https://wiki.libsdl.org/SDL_ConvertAudio
 */
int audio_resampleLoss()
{
  /* Note: always test long input time (>= 5s from experience) in some test
   * cases because an improper implementation may suffer from low resampling
   * precision with long input due to e.g. doing subtraction with large floats. */
  struct test_spec_t {
    int time;
    int freq;
    double phase;
    int rate_in;
    int rate_out;
    double signal_to_noise;
    double max_error;
  } test_specs[] = {
    { 50, 440, 0, 44100, 48000, 60, 0.0025 },
    { 50, 5000, M_PI / 2, 20000, 10000, 65, 0.0010 },
    { 0 }
  };

  int spec_idx = 0;

  for (spec_idx = 0; test_specs[spec_idx].time > 0; ++spec_idx) {
    const struct test_spec_t *spec = &test_specs[spec_idx];
    const int frames_in = spec->time * spec->rate_in;
    const int frames_target = spec->time * spec->rate_out;
    const int len_in = frames_in * (int)sizeof(float);
    const int len_target = frames_target * (int)sizeof(float);

    Uint64 tick_beg = 0;
    Uint64 tick_end = 0;
    SDL_AudioCVT cvt;
    int i = 0;
    int ret = 0;
    double max_error = 0;
    double sum_squared_error = 0;
    double sum_squared_value = 0;
    double signal_to_noise = 0;

    SDLTest_AssertPass("Test resampling of %i s %i Hz %f phase sine wave from sampling rate of %i Hz to %i Hz",
                       spec->time, spec->freq, spec->phase, spec->rate_in, spec->rate_out);

    ret = SDL_BuildAudioCVT(&cvt, AUDIO_F32, 1, spec->rate_in, AUDIO_F32, 1, spec->rate_out);
    SDLTest_AssertPass("Call to SDL_BuildAudioCVT(&cvt, AUDIO_F32, 1, %i, AUDIO_F32, 1, %i)", spec->rate_in, spec->rate_out);
    SDLTest_AssertCheck(ret == 1, "Expected SDL_BuildAudioCVT to succeed and conversion to be needed.");
    if (ret != 1) {
      return TEST_ABORTED;
    }

    cvt.buf = (Uint8 *)SDL_malloc(len_in * cvt.len_mult);
    SDLTest_AssertCheck(cvt.buf != NULL, "Expected input buffer to be created.");
    if (cvt.buf == NULL) {
      return TEST_ABORTED;
    }

    cvt.len = len_in;
    for (i = 0; i < frames_in; ++i) {
      *(((float *) cvt.buf) + i) = (float)sine_wave_sample(i, spec->rate_in, spec->freq, spec->phase);
    }

    tick_beg = SDL_GetPerformanceCounter();
    ret = SDL_ConvertAudio(&cvt);
    tick_end = SDL_GetPerformanceCounter();
    SDLTest_AssertPass("Call to SDL_ConvertAudio(&cvt)");
    SDLTest_AssertCheck(ret == 0, "Expected SDL_ConvertAudio to succeed.");
    SDLTest_AssertCheck(cvt.len_cvt == len_target, "Expected output length %i, got %i.", len_target, cvt.len_cvt);
    if (ret != 0 || cvt.len_cvt != len_target) {
      SDL_free(cvt.buf);
      return TEST_ABORTED;
    }
    SDLTest_Log("Resampling used %f seconds.", ((double) (tick_end - tick_beg)) / SDL_GetPerformanceFrequency());

    for (i = 0; i < frames_target; ++i) {
        const float output = *(((float *) cvt.buf) + i);
        const double target = sine_wave_sample(i, spec->rate_out, spec->freq, spec->phase);
        const double error = SDL_fabs(target - output);
        max_error = SDL_max(max_error, error);
        sum_squared_error += error * error;
        sum_squared_value += target * target;
    }
    SDL_free(cvt.buf);
    signal_to_noise = 10 * SDL_log10(sum_squared_value / sum_squared_error); /* decibel */
    SDLTest_AssertCheck(isfinite(sum_squared_value), "Sum of squared target should be finite.");
    SDLTest_AssertCheck(isfinite(sum_squared_error), "Sum of squared error should be finite.");
    /* Infinity is theoretically possible when there is very little to no noise */
    SDLTest_AssertCheck(!isnan(signal_to_noise), "Signal-to-noise ratio should not be NaN.");
    SDLTest_AssertCheck(isfinite(max_error), "Maximum conversion error should be finite.");
    SDLTest_AssertCheck(signal_to_noise >= spec->signal_to_noise, "Conversion signal-to-noise ratio %f dB should be no less than %f dB.",
                        signal_to_noise, spec->signal_to_noise);
    SDLTest_AssertCheck(max_error <= spec->max_error, "Maximum conversion error %f should be no more than %f.",
                        max_error, spec->max_error);
  }

  return TEST_COMPLETED;
}

/* ================= Test Case References ================== */

/* Audio test cases */
static const SDLTest_TestCaseReference audioTest1 = {
    (SDLTest_TestCaseFp)audio_enumerateAndNameAudioDevices, "audio_enumerateAndNameAudioDevices", "Enumerate and name available audio devices (output and capture)", TEST_ENABLED
};

static const SDLTest_TestCaseReference audioTest2 = {
    (SDLTest_TestCaseFp)audio_enumerateAndNameAudioDevicesNegativeTests, "audio_enumerateAndNameAudioDevicesNegativeTests", "Negative tests around enumeration and naming of audio devices.", TEST_ENABLED
};

static const SDLTest_TestCaseReference audioTest3 = {
    (SDLTest_TestCaseFp)audio_printAudioDrivers, "audio_printAudioDrivers", "Checks available audio driver names.", TEST_ENABLED
};

static const SDLTest_TestCaseReference audioTest4 = {
    (SDLTest_TestCaseFp)audio_printCurrentAudioDriver, "audio_printCurrentAudioDriver", "Checks current audio driver name with initialized audio.", TEST_ENABLED
};

static const SDLTest_TestCaseReference audioTest5 = {
    (SDLTest_TestCaseFp)audio_buildAudioCVT, "audio_buildAudioCVT", "Builds various audio conversion structures.", TEST_ENABLED
};

static const SDLTest_TestCaseReference audioTest6 = {
    (SDLTest_TestCaseFp)audio_buildAudioCVTNegative, "audio_buildAudioCVTNegative", "Checks calls with invalid input to SDL_BuildAudioCVT", TEST_ENABLED
};

static const SDLTest_TestCaseReference audioTest7 = {
    (SDLTest_TestCaseFp)audio_getAudioStatus, "audio_getAudioStatus", "Checks current audio status.", TEST_ENABLED
};

static const SDLTest_TestCaseReference audioTest8 = {
    (SDLTest_TestCaseFp)audio_openCloseAndGetAudioStatus, "audio_openCloseAndGetAudioStatus", "Opens and closes audio device and get audio status.", TEST_ENABLED
};

static const SDLTest_TestCaseReference audioTest9 = {
    (SDLTest_TestCaseFp)audio_lockUnlockOpenAudioDevice, "audio_lockUnlockOpenAudioDevice", "Locks and unlocks an open audio device.", TEST_ENABLED
};

/* TODO: enable test when SDL_ConvertAudio segfaults on cygwin have been fixed.    */
/* For debugging, test case can be run manually using --filter audio_convertAudio  */

static const SDLTest_TestCaseReference audioTest10 = {
    (SDLTest_TestCaseFp)audio_convertAudio, "audio_convertAudio", "Convert audio using available formats.", TEST_DISABLED
};

/* TODO: enable test when SDL_AudioDeviceConnected has been implemented.           */

static const SDLTest_TestCaseReference audioTest11 = {
    (SDLTest_TestCaseFp)audio_openCloseAudioDeviceConnected, "audio_openCloseAudioDeviceConnected", "Opens and closes audio device and get connected status.", TEST_DISABLED
};

static const SDLTest_TestCaseReference audioTest12 = {
    (SDLTest_TestCaseFp)audio_quitInitAudioSubSystem, "audio_quitInitAudioSubSystem", "Quit and re-init audio subsystem.", TEST_ENABLED
};

static const SDLTest_TestCaseReference audioTest13 = {
    (SDLTest_TestCaseFp)audio_initQuitAudio, "audio_initQuitAudio", "Init and quit audio drivers directly.", TEST_ENABLED
};

static const SDLTest_TestCaseReference audioTest14 = {
    (SDLTest_TestCaseFp)audio_initOpenCloseQuitAudio, "audio_initOpenCloseQuitAudio", "Cycle through init, open, close and quit with various audio specs.", TEST_ENABLED
};

static const SDLTest_TestCaseReference audioTest15 = {
    (SDLTest_TestCaseFp)audio_pauseUnpauseAudio, "audio_pauseUnpauseAudio", "Pause and Unpause audio for various audio specs while testing callback.", TEST_ENABLED
};

static const SDLTest_TestCaseReference audioTest16 = {
    (SDLTest_TestCaseFp)audio_resampleLoss, "audio_resampleLoss", "Check signal-to-noise ratio and maximum error of audio resampling.", TEST_ENABLED
};

/* Sequence of Audio test cases */
static const SDLTest_TestCaseReference *audioTests[] = {
    &audioTest1, &audioTest2, &audioTest3, &audioTest4, &audioTest5, &audioTest6,
    &audioTest7, &audioTest8, &audioTest9, &audioTest10, &audioTest11,
    &audioTest12, &audioTest13, &audioTest14, &audioTest15, &audioTest16, NULL
};

/* Audio test suite (global) */
SDLTest_TestSuiteReference audioTestSuite = {
    "Audio",
    _audioSetUp,
    audioTests,
    _audioTearDown
};