Add sine integration test

examples/sine.rs

@@ -44,7 +44,7 @@ fn main() -> Result<(), coreaudio::Error> {
     // Read the input format. This is counterintuitive, but it's the format used when sending
     // audio data to the AudioUnit representing the output device. This is separate from the
     // format the AudioUnit later uses to send the data to the hardware device.
-    let stream_format = audio_unit.input_stream_format()?;
+    let stream_format = audio_unit.output_stream_format()?;
     println!("{:#?}", &stream_format);
 
     // For this example, our sine wave expects `f32` data.

tests/sine.rs

@@ -0,0 +1,75 @@
+
+//! A basic output stream example, using an Output AudioUnit to generate a sine wave.
+
+extern crate coreaudio;
+
+use coreaudio::audio_unit::render_callback::{self, data};
+use coreaudio::audio_unit::{AudioUnit, IOType, SampleFormat};
+use std::f64::consts::PI;
+
+struct SineWaveGenerator {
+    time: f64,
+    /// generated frequency in Hz
+    freq: f64,
+    /// magnitude of generated signal
+    volume: f64,
+}
+
+impl SineWaveGenerator {
+    fn new(freq: f64, volume: f64) -> Self {
+        SineWaveGenerator {
+            time: 0.,
+            freq,
+            volume,
+        }
+    }
+}
+
+impl Iterator for SineWaveGenerator {
+    type Item = f32;
+    fn next(&mut self) -> Option<f32> {
+        self.time += 1. / 44_100.;
+        let output = ((self.freq * self.time * PI * 2.).sin() * self.volume) as f32;
+        Some(output)
+    }
+}
+
+#[test]
+fn sine() -> Result<(), coreaudio::Error> {
+    let frequency_hz = 440.;
+    let volume = 0.15;
+    let mut samples = SineWaveGenerator::new(frequency_hz, volume);
+
+    // Construct an Output audio unit that delivers audio to the default output device.
+    let mut audio_unit = AudioUnit::new(IOType::DefaultOutput)?;
+
+    // Read the input format. This is counterintuitive, but it's the format used when sending
+    // audio data to the AudioUnit representing the output device. This is separate from the
+    // format the AudioUnit later uses to send the data to the hardware device.
+    let stream_format = audio_unit.output_stream_format()?;
+    println!("{:#?}", &stream_format);
+
+    // For this example, our sine wave expects `f32` data.
+    assert!(SampleFormat::F32 == stream_format.sample_format);
+
+    type Args = render_callback::Args<data::NonInterleaved<f32>>;
+    audio_unit.set_render_callback(move |args| {
+        let Args {
+            num_frames,
+            mut data,
+            ..
+        } = args;
+        for i in 0..num_frames {
+            let sample = samples.next().unwrap();
+            for channel in data.channels_mut() {
+                channel[i] = sample;
+            }
+        }
+        Ok(())
+    })?;
+    audio_unit.start()?;
+
+    std::thread::sleep(std::time::Duration::from_millis(50));
+
+    Ok(())
+}