tests(pyargus): add test cases for signals

pyargus/src/signals.rs

@@ -1,5 +1,6 @@
 use std::time::Duration;
 
+use argus_core::signals::interpolation::Linear;
 use argus_core::signals::Signal;
 use pyo3::prelude::*;
 
@@ -83,6 +84,45 @@ macro_rules! impl_signals {
                     self.0.push(Duration::from_secs_f64(time), value)?;
                     Ok(())
                 }
+
+                /// Check if the signal is empty
+                fn is_empty(&self) -> bool {
+                    self.0.is_empty()
+                }
+
+                /// The start time of the signal
+                #[getter]
+                fn start_time(&self) -> Option<f64> {
+                    use core::ops::Bound::*;
+                    match self.0.start_time()? {
+                        Included(t) | Excluded(t) => Some(t.as_secs_f64()),
+                        _ => None,
+                    }
+                }
+
+                /// The end time of the signal
+                #[getter]
+                fn end_time(&self) -> Option<f64> {
+                    use core::ops::Bound::*;
+                    match self.0.end_time()? {
+                        Included(t) | Excluded(t) => Some(t.as_secs_f64()),
+                        _ => None,
+                    }
+                }
+
+                /// Get the value of the signal at the given time point.
+                ///
+                /// If there exists a sample, then the value is returned, otherwise the value is
+                /// interpolated. If the time point lies outside of the domain of the signal, then `None`
+                /// is returned.
+                fn at(self_: PyRef<'_, Self>, time: f64) -> Option<$ty> {
+                    let super_ = self_.as_ref();
+                    let time = core::time::Duration::from_secs_f64(time);
+                    match super_.interpolation {
+                        PyInterp::Linear => self_.0.interpolate_at::<Linear>(time),
+                    }
+                }
+
             }
         }
     };