1 files changed, 118 insertions, 0 deletions
diff --git a/tests/audio/test_audio.cpp b/tests/audio/test_audio.cpp
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--- /dev/null
+++ b/tests/audio/test_audio.cpp
@@ -0,0 +1,118 @@
+// Copyright 2023 Google LLC
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 2 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#include <cmath>
+#include <random>
+
+#include "gtest/gtest.h"
+#include "keyboard_report_util.hpp"
+#include "test_common.hpp"
+
+namespace {
+
+class AudioTest : public TestFixture {
+   public:
+    uint16_t infer_tempo() {
+        return audio_ms_to_duration(1875) / 2;
+    }
+};
+
+TEST_F(AudioTest, OnOffToggle) {
+    audio_on();
+    EXPECT_TRUE(audio_is_on());
+
+    audio_off();
+    EXPECT_FALSE(audio_is_on());
+
+    audio_toggle();
+    EXPECT_TRUE(audio_is_on());
+
+    audio_toggle();
+    EXPECT_FALSE(audio_is_on());
+}
+
+TEST_F(AudioTest, ChangeTempo) {
+    for (int tempo = 50; tempo <= 250; tempo += 50) {
+        audio_set_tempo(tempo);
+        EXPECT_EQ(infer_tempo(), tempo);
+    }
+
+    audio_set_tempo(10);
+    audio_increase_tempo(25);
+    EXPECT_EQ(infer_tempo(), 35);
+
+    audio_decrease_tempo(4);
+    EXPECT_EQ(infer_tempo(), 31);
+
+    audio_increase_tempo(250);
+    EXPECT_EQ(infer_tempo(), 255);
+
+    audio_set_tempo(9);
+    EXPECT_EQ(infer_tempo(), 10);
+
+    audio_decrease_tempo(100);
+    EXPECT_EQ(infer_tempo(), 10);
+}
+
+TEST_F(AudioTest, BpmConversion) {
+    const int tol = 1;
+
+    audio_set_tempo(120);
+    // At 120 bpm, there are 2 beats per second, and a whole note is 500 ms.
+    EXPECT_NEAR(audio_duration_to_ms(64 /* whole note */), 500, tol);
+    EXPECT_NEAR(audio_ms_to_duration(500), 64, tol);
+    EXPECT_EQ(audio_duration_to_ms(0), 0);
+    EXPECT_EQ(audio_ms_to_duration(0), 0);
+
+    audio_set_tempo(10);
+    // At 10 bpm, UINT16_MAX ms corresponds to 699/64 beats and is the longest
+    // duration that can be converted without overflow.
+    EXPECT_NEAR(audio_ms_to_duration(UINT16_MAX), 699, tol);
+    EXPECT_NEAR(audio_duration_to_ms(699), 65531, tol);
+
+    audio_set_tempo(255);
+    // At 255 bpm, UINT16_MAX ms corresponds to 17825/64 beats and is the longest
+    // duration that can be converted without overflow.
+    EXPECT_NEAR(audio_ms_to_duration(UINT16_MAX), 17825, tol);
+    EXPECT_NEAR(audio_duration_to_ms(17825), 65533, tol);
+
+    std::mt19937                       rng(0 /*seed*/);
+    std::uniform_int_distribution<int> dist_tempo(10, 255);
+    std::uniform_int_distribution<int> dist_ms(0, UINT16_MAX);
+
+    // Test bpm <-> ms conversions for random tempos and durations.
+    for (int trial = 0; trial < 50; ++trial) {
+        const int tempo       = dist_tempo(rng);
+        const int duration_ms = dist_ms(rng);
+        SCOPED_TRACE("tempo " + testing::PrintToString(tempo) + ", duration " + testing::PrintToString(duration_ms) + " ms");
+
+        audio_set_tempo(tempo);
+        int duration_bpm = std::round((64.0f / (60.0f * 1000.0f)) * duration_ms * tempo);
+        ASSERT_NEAR(audio_ms_to_duration(duration_ms), duration_bpm, tol);
+
+        int roundtrip_ms = std::round((60.0f * 1000.0f / 64.0f) * duration_bpm / tempo);
+        // Because of round-off error, duration_ms and roundtrip_ms may differ by
+        // about (60 * 1000 / 64) / tempo.
+        int roundtrip_tol = tol * (60.0f * 1000.0f / 64.0f) / tempo;
+        ASSERT_NEAR(roundtrip_ms, duration_ms, roundtrip_tol);
+
+        // Only test converting back to ms if the result would be in uint16_t range.
+        if (roundtrip_ms <= UINT16_MAX) {
+            ASSERT_NEAR(audio_duration_to_ms(duration_bpm), roundtrip_ms, tol);
+        }
+    }
+}
+
+} // namespace