Add shift unit tests

src/transform/shift.rs

@@ -23,3 +23,62 @@ impl Pattern for Shift {
         self.child.sample(pos) + 1.0 - 2.0 * self.shift
     }
 }
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use crate::MockPatternFactory;
+    use mockall::predicate::eq;
+
+    #[test]
+    fn create_config_correct() {
+        let config = Config {
+            size: Vector::new(4.0, 2.0),
+            step: 0.4,
+        };
+        let mut child = MockPatternFactory::new();
+        child
+            .expect_create()
+            .with(eq(config))
+            .once()
+            .returning(|_| Box::new(MockPattern::new()));
+
+        ShiftFactory::new(Box::new(child)).create(&config);
+    }
+
+    #[test]
+    fn sample_shifted() {
+        let config = Config {
+            size: Vector::default(),
+            step: 0.4,
+        };
+        let mut child = MockPatternFactory::new();
+        child.expect_create().returning(|_| {
+            let mut sampler = MockPattern::new();
+            sampler.expect_sample().return_const(0.6);
+            Box::new(sampler)
+        });
+
+        let sampler = ShiftFactory::new(Box::new(child)).create(&config);
+
+        assert_eq!(0.8, 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(6.0, 7.0)))
+                .once()
+                .return_const(0.0);
+            Box::new(sampler)
+        });
+
+        let sampler = ShiftFactory::new(Box::new(child)).create(&Config::default());
+
+        sampler.sample(Vector::new(6.0, 7.0));
+    }
+}