diff --git a/Cargo.toml b/Cargo.toml
index 9b3eff2..baa0d46 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -10,4 +10,5 @@ repository = "https://github.com/ricoriedel/wipe"
 anyhow = "1.0"
 clap = { version = "3.1", features = ["derive"]}
 crossterm = "0.23"
-rand = "0.8"
\ No newline at end of file
+rand = "0.8"
+mockall = "0.11"
\ No newline at end of file
diff --git a/src/main.rs b/src/main.rs
index f6b4bcf..d59762d 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -10,6 +10,7 @@ use crate::color::{ColorSampler, SimpleColorSampler};
 use crate::fill::circle::CircleFillMode;
 use crate::fill::FillMode;
 use crate::fill::level::LevelFillMode;
+use crate::render::{Renderer, SamplerRenderer};
 use crate::sampler::ComposedSampler;
 use crate::surface::WriteSurface;
 use crate::vec::Vector;
@@ -22,6 +23,7 @@ mod array;
 mod surface;
 mod animation;
 mod sampler;
+mod render;
 
 #[derive(Copy, Clone, ArgEnum)]
 enum AnimationType {
@@ -76,8 +78,13 @@ fn main() -> Result<(), Error> {
     let color = create_color(args.color[0]);
     let char = Box::new(SimpleCharSampler::new(args.chars));
 
-    let _ = Box::new(ComposedSampler::new(animation, fill, color, char));
-    let _ = Box::new(WriteSurface::new(stdout(), width, height));
+    let sampler = Box::new(ComposedSampler::new(animation, fill, color, char));
+    let surface = Box::new(WriteSurface::new(stdout(), width, height));
+
+    let mut renderer = Box::new(SamplerRenderer::new(surface, sampler));
+
+    renderer.render(0.5);
+    renderer.present()?;
 
     Ok(())
 }
diff --git a/src/render.rs b/src/render.rs
new file mode 100644
index 0000000..8268cd0
--- /dev/null
+++ b/src/render.rs
@@ -0,0 +1,87 @@
+use anyhow::Error;
+use crate::sampler::{Sample, Sampler};
+use crate::surface::Surface;
+use crate::Vector;
+
+pub trait Renderer {
+    fn render(&mut self, step: f32);
+    fn present(&mut self) -> Result<(), Error>;
+}
+
+pub struct SamplerRenderer {
+    surface: Box<dyn Surface>,
+    sampler: Box<dyn Sampler>,
+}
+
+impl SamplerRenderer {
+    pub fn new(surface: Box<dyn Surface>,
+               sampler: Box<dyn Sampler>) -> Self {
+        Self { surface, sampler }
+    }
+}
+
+impl Renderer for SamplerRenderer {
+    fn render(&mut self, step: f32) {
+        for x in 0..self.surface.width() {
+            for y in 0..self.surface.height() {
+                let pos = Vector::from_terminal(x, y);
+                let sample = self.sampler.sample(step, pos);
+
+                match sample {
+                    Sample::Keep => (),
+                    Sample::Draw { char, color } => self.surface.draw(x, y, char, color),
+                    Sample::Clear => self.surface.clear(x, y),
+                }
+            }
+        }
+    }
+
+    fn present(&mut self) -> Result<(), Error> {
+        self.surface.present()
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use crossterm::style::*;
+    use mockall::predicate::*;
+    use super::*;
+    use crate::surface::MockSurface;
+    use crate::sampler::MockSampler;
+
+    #[test]
+    fn render() {
+        let mut surface = Box::new(MockSurface::new());
+        let mut sampler = Box::new(MockSampler::new());
+
+        sampler.expect_sample().withf(|_, pos| pos.x == 0.0 && pos.y == 0.0).returning(|_,_| Sample::Clear);
+        sampler.expect_sample().withf(|_, pos| pos.x == 1.0 && pos.y == 0.0).returning(|_,_| Sample::Keep);
+        sampler.expect_sample().withf(|_, pos| pos.x == 0.0 && pos.y == 2.0).returning(|_,_| Sample::Draw { char: 'a', color: Color::Red });
+        sampler.expect_sample().withf(|_, pos| pos.x == 1.0 && pos.y == 2.0).returning(|_,_| Sample::Keep);
+        sampler.expect_sample().withf(|_, pos| pos.x == 0.0 && pos.y == 4.0).returning(|_,_| Sample::Draw { char: 'x', color: Color::Yellow });
+        sampler.expect_sample().withf(|_, pos| pos.x == 1.0 && pos.y == 4.0).returning(|_,_| Sample::Clear);
+
+        surface.expect_width().return_const(2 as usize);
+        surface.expect_height().return_const(3 as usize);
+        surface.expect_clear().once().with(eq(0), eq(0)).return_const(());
+        surface.expect_draw().once().with(eq(0), eq(1), eq('a'), eq(Color::Red)).return_const(());
+        surface.expect_draw().once().with(eq(0), eq(2), eq('x'), eq(Color::Yellow)).return_const(());
+        surface.expect_clear().once().with(eq(1), eq(2)).return_const(());
+
+        let mut renderer = SamplerRenderer::new(surface, sampler);
+
+        renderer.render(0.5);
+    }
+
+    #[test]
+    fn present() {
+        let mut surface = Box::new(MockSurface::new());
+        let sampler = Box::new(MockSampler::new());
+
+        surface.expect_present().once().returning(|| Ok(()));
+
+        let mut renderer = SamplerRenderer::new(surface, sampler);
+
+        renderer.present().unwrap();
+    }
+}
\ No newline at end of file
diff --git a/src/sampler.rs b/src/sampler.rs
index 3643fff..bb6a7f7 100644
--- a/src/sampler.rs
+++ b/src/sampler.rs
@@ -1,4 +1,5 @@
 use crossterm::style::Color;
+use mockall::automock;
 use crate::animation::Animation;
 use crate::char::CharSampler;
 use crate::color::ColorSampler;
@@ -11,6 +12,7 @@ pub enum Sample {
     Clear,
 }
 
+#[automock]
 pub trait Sampler {
     fn sample(&self, step: f32, pos: Vector) -> Sample;
 }
diff --git a/src/surface.rs b/src/surface.rs
index b0b1093..3096f5f 100644
--- a/src/surface.rs
+++ b/src/surface.rs
@@ -3,9 +3,11 @@ use crossterm::cursor::MoveTo;
 use crossterm::{ExecutableCommand, QueueableCommand};
 use crossterm::style::{Color, Print, SetForegroundColor};
 use crossterm::terminal::{Clear, ClearType};
+use mockall::automock;
 use std::io::Write;
 use crate::array::Array2D;
 
+#[automock]
 pub trait Surface {
     fn width(&self) -> usize;
     fn height(&self) -> usize;