diff --git a/src/render.rs b/src/render.rs
index 6e7ae9b..b6b35b1 100644
--- a/src/render.rs
+++ b/src/render.rs
@@ -3,6 +3,9 @@ use crate::sampler::{Sample, Sampler};
 use crate::surface::Surface;
 use crate::Vector;
 
+use mockall::automock;
+
+#[automock]
 pub trait Renderer {
     fn render(&mut self, step: f32);
     fn present(&mut self) -> Result<(), Error>;
diff --git a/src/runner.rs b/src/runner.rs
index 6ff01be..217a7cc 100644
--- a/src/runner.rs
+++ b/src/runner.rs
@@ -19,7 +19,7 @@ impl<T1: Timer, T2: Renderer> Runner<T1, T2> {
     }
 
     pub fn run(mut self) -> Result<(), Error> {
-        for i in 0..self.ticks {
+        for i in 0..=self.ticks {
             let step = i as f32 / self.ticks as f32;
 
             self.renderer.render(step);
@@ -28,4 +28,41 @@ impl<T1: Timer, T2: Renderer> Runner<T1, T2> {
         }
         self.renderer.finish()
     }
+}
+
+#[cfg(test)]
+mod test {
+    use std::time::Duration;
+    use mockall::predicate::*;
+    use mockall::Sequence;
+    use crate::timer::MockTimer;
+    use crate::render::MockRenderer;
+    use super::*;
+
+    #[test]
+    fn run() {
+        let mut timer = MockTimer::new();
+        let mut renderer = MockRenderer::new();
+        let seq = &mut Sequence::new();
+
+        timer.expect_delay().return_const(Duration::from_secs(2));
+
+        renderer.expect_render().once().with(eq(0.0)).in_sequence(seq).return_const(());
+        renderer.expect_present().once().in_sequence(seq).returning(|| Ok(()));
+        timer.expect_sleep().once().in_sequence(seq).return_const(());
+
+        renderer.expect_render().once().with(eq(0.5)).in_sequence(seq).return_const(());
+        renderer.expect_present().once().in_sequence(seq).returning(|| Ok(()));
+        timer.expect_sleep().once().in_sequence(seq).return_const(());
+
+        renderer.expect_render().once().with(eq(1.0)).in_sequence(seq).return_const(());
+        renderer.expect_present().once().in_sequence(seq).returning(|| Ok(()));
+        timer.expect_sleep().once().in_sequence(seq).return_const(());
+
+        renderer.expect_finish().once().in_sequence(seq).returning(|| Ok(()));
+
+        let runner = Runner::new(Duration::from_secs(4), timer, renderer);
+
+        runner.run().unwrap();
+    }
 }
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