diff --git a/src/pattern/mod.rs b/src/pattern/mod.rs
index 764a047..96b1b77 100644
--- a/src/pattern/mod.rs
+++ b/src/pattern/mod.rs
@@ -10,12 +10,13 @@ pub use wheel::*;
 
 use crate::Vector;
 
-#[derive(Copy, Clone, PartialEq, Debug)]
+#[derive(Copy, Clone, Default, PartialEq, Debug)]
 pub struct Config {
     pub size: Vector,
     pub step: f32,
 }
 
+#[cfg_attr(test, mockall::automock)]
 pub trait PatternFactory {
     fn create(&self, config: &Config) -> Box<dyn Pattern>;
 }
diff --git a/src/transform/invert.rs b/src/transform/invert.rs
index 4f092f0..7744d4e 100644
--- a/src/transform/invert.rs
+++ b/src/transform/invert.rs
@@ -25,3 +25,61 @@ impl Pattern for Invert {
         1.0 - self.child.sample(pos)
     }
 }
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use crate::MockPatternFactory;
+    use mockall::predicate::eq;
+
+    #[test]
+    fn create_config_correct() {
+        let input = Config {
+            size: Vector::new(4.0, 2.0),
+            step: 0.4,
+        };
+        let mut output = input.clone();
+        output.step = 0.6;
+
+        let mut child = MockPatternFactory::new();
+        child
+            .expect_create()
+            .with(eq(output))
+            .once()
+            .returning(|_| Box::new(MockPattern::new()));
+
+        InvertFactory::new(Box::new(child)).create(&input);
+    }
+
+    #[test]
+    fn sample_inverted() {
+        let mut child = MockPatternFactory::new();
+        child.expect_create().returning(|_| {
+            let mut sampler = MockPattern::new();
+            sampler.expect_sample().return_const(0.7);
+            Box::new(sampler)
+        });
+
+        let sampler = InvertFactory::new(Box::new(child)).create(&Config::default());
+
+        assert_eq!(0.3, sampler.sample(Vector::default()));
+    }
+
+    #[test]
+    fn sample_pos_correct() {
+        let mut child = MockPatternFactory::new();
+        child.expect_create().once().returning(|_| {
+            let mut sampler = MockPattern::new();
+            sampler
+                .expect_sample()
+                .with(eq(Vector::new(4.0, 2.0)))
+                .once()
+                .return_const(0.0);
+            Box::new(sampler)
+        });
+
+        let sampler = InvertFactory::new(Box::new(child)).create(&Config::default());
+
+        sampler.sample(Vector::new(4.0, 2.0));
+    }
+}