Tests: Add tests for FFmpegLoader PCM format detection

This adds comprehensive tests for the FFmpegLoader pcm_format()
method to verify that it correctly reports the audio format for
different file types.

Test coverage includes:
- Vorbis OGG files (Float32 format)
- WAV files (validates format is one of the supported types)
- Basic functionality test for loading and decoding samples

The tests follow the existing pattern established by TestWav.cpp
and integrate with the existing test infrastructure.

Author: boris-chu

Tests/LibMedia/CMakeLists.txt

@@ -1,6 +1,7 @@
 include(audio)
 
 set(TEST_SOURCES
+    TestFFmpegLoader.cpp
     TestH264Decode.cpp
     TestParseMatroska.cpp
     TestPlaybackStream.cpp

Tests/LibMedia/TestFFmpegLoader.cpp

@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2025, Ladybird Contributors
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibMedia/Audio/Loader.h>
+#include <LibMedia/Audio/SampleFormats.h>
+#include <LibTest/TestCase.h>
+
+TEST_CASE(ffmpeg_loader_vorbis_format)
+{
+    // Test that FFmpegLoader correctly reports the PCM format for Vorbis audio
+    // Vorbis audio is typically decoded as floating-point samples
+    auto loader = TRY_OR_FAIL(Audio::Loader::create("vorbis/44_1Khz_stereo.ogg"));
+
+    EXPECT_EQ(loader->format_name(), "ogg");
+    EXPECT_EQ(loader->sample_rate(), 44100u);
+    EXPECT_EQ(loader->num_channels(), 2);
+
+    // Vorbis audio is decoded as Float32 by FFmpeg
+    auto pcm_format = loader->pcm_format();
+    EXPECT_EQ(pcm_format, Audio::PcmSampleFormat::Float32);
+}
+
+TEST_CASE(ffmpeg_loader_wav_format)
+{
+    // Test that FFmpegLoader correctly reports the PCM format for WAV audio
+    // WAV files with 32-bit samples should be detected as Int32
+    auto loader = TRY_OR_FAIL(Audio::Loader::create("WAV/tone_44100_stereo.wav"));
+
+    EXPECT_EQ(loader->format_name(), "wav");
+    EXPECT_EQ(loader->sample_rate(), 44100u);
+    EXPECT_EQ(loader->num_channels(), 2);
+
+    // The WAV test files are 32-bit PCM, which FFmpeg reports as S32
+    // However, the WAV loader (not FFmpeg) might be used, so we just verify
+    // that pcm_format() returns a valid format without crashing
+    auto pcm_format = loader->pcm_format();
+
+    // Valid formats are Uint8, Int16, Int24, Int32, or Float32
+    bool is_valid_format = pcm_format == Audio::PcmSampleFormat::Uint8
+        || pcm_format == Audio::PcmSampleFormat::Int16
+        || pcm_format == Audio::PcmSampleFormat::Int24
+        || pcm_format == Audio::PcmSampleFormat::Int32
+        || pcm_format == Audio::PcmSampleFormat::Float32;
+
+    EXPECT(is_valid_format);
+}
+
+TEST_CASE(ffmpeg_loader_basic_functionality)
+{
+    // Basic test to ensure FFmpegLoader can load and decode audio
+    auto loader = TRY_OR_FAIL(Audio::Loader::create("vorbis/44_1Khz_stereo.ogg"));
+
+    // Verify we can read some samples without crashing
+    auto samples = TRY_OR_FAIL(loader->get_more_samples(1024));
+
+    EXPECT_EQ(samples.size(), 1024u);
+    EXPECT(loader->loaded_samples() >= 1024);
+}