Merge pull request #291 from bjz/cleanup-matrix-tests

Clean up matrix tests

tests/matrix.rs

@@ -16,390 +16,542 @@
 #[macro_use]
 extern crate cgmath;
 
-use cgmath::*;
-use std::f64;
-
 pub mod matrix2 {
+    use std::f64;
+
     use cgmath::*;
 
-    pub static A: Matrix2<f64> = Matrix2 { x: Vector2 { x: 1.0f64, y: 3.0f64 },
-                                           y: Vector2 { x: 2.0f64, y: 4.0f64 } };
-    pub static B: Matrix2<f64> = Matrix2 { x: Vector2 { x: 2.0f64, y: 4.0f64 },
-                                           y: Vector2 { x: 3.0f64, y: 5.0f64 } };
-    pub static C: Matrix2<f64> = Matrix2 { x: Vector2 { x: 2.0f64, y: 1.0f64 },
-                                           y: Vector2 { x: 1.0f64, y: 2.0f64 } };
+    const A: Matrix2<f64> = Matrix2 { x: Vector2 { x: 1.0f64, y: 3.0f64 },
+                                      y: Vector2 { x: 2.0f64, y: 4.0f64 } };
+    const B: Matrix2<f64> = Matrix2 { x: Vector2 { x: 2.0f64, y: 4.0f64 },
+                                      y: Vector2 { x: 3.0f64, y: 5.0f64 } };
+    const C: Matrix2<f64> = Matrix2 { x: Vector2 { x: 2.0f64, y: 1.0f64 },
+                                      y: Vector2 { x: 1.0f64, y: 2.0f64 } };
 
-    pub static V: Vector2<f64> = Vector2 { x: 1.0f64, y: 2.0f64 };
-    pub static F: f64 = 0.5;
+    const V: Vector2<f64> = Vector2 { x: 1.0f64, y: 2.0f64 };
+    const F: f64 = 0.5;
+
+    #[test]
+    fn test_neg() {
+        assert_eq!(-A,
+                   Matrix2::new(-1.0f64, -3.0f64,
+                                -2.0f64, -4.0f64));
+    }
+
+    #[test]
+    fn test_mul_scalar() {
+        assert_eq!(A * F,
+                   Matrix2::new(0.5f64, 1.5f64,
+                                1.0f64, 2.0f64));
+    }
+
+    #[test]
+    fn test_add_matrix() {
+        assert_eq!(A + B,
+                   Matrix2::new(3.0f64, 7.0f64,
+                                5.0f64, 9.0f64));
+    }
+
+    #[test]
+    fn test_sub_matrix() {
+        assert_eq!(A - B,
+                   Matrix2::new(-1.0f64, -1.0f64,
+                                -1.0f64, -1.0f64));
+    }
+
+    #[test]
+    fn test_mul_vector() {
+        assert_eq!(A * V, Vector2::new(5.0f64, 11.0f64));
+    }
+
+    #[test]
+    fn test_mul_matrix() {
+        assert_eq!(A * B,
+                   Matrix2::new(10.0f64, 22.0f64,
+                                13.0f64, 29.0f64));
+
+        assert_eq!(A * B, &A * &B);
+    }
+
+    #[test]
+    fn test_determinant() {
+        assert_eq!(A.determinant(), -2.0f64)
+    }
+
+    #[test]
+    fn test_trace() {
+        assert_eq!(A.trace(), 5.0f64);
+    }
+
+    #[test]
+    fn test_transpose() {
+        assert_eq!(A.transpose(),
+                   Matrix2::<f64>::new(1.0f64, 2.0f64,
+                                       3.0f64, 4.0f64));
+    }
+
+    #[test]
+    fn test_transpose_self() {
+        let mut mut_a = A;
+        mut_a.transpose_self();
+        assert_eq!(mut_a, A.transpose());
+    }
+
+    #[test]
+    fn test_invert() {
+        assert!(Matrix2::<f64>::identity().invert().unwrap().is_identity());
+
+        assert_eq!(A.invert().unwrap(),
+                   Matrix2::new(-2.0f64,  1.5f64,
+                                 1.0f64, -0.5f64));
+        assert!(Matrix2::new(0.0f64, 2.0f64,
+                             0.0f64, 5.0f64).invert().is_none());
+    }
+
+    #[test]
+    fn test_invert_self() {
+        let mut mut_a = A;
+        mut_a.invert_self();
+        assert_eq!(mut_a, A.invert().unwrap());
+    }
+
+    #[test]
+    fn test_predicates() {
+        assert!(Matrix2::<f64>::identity().is_identity());
+        assert!(Matrix2::<f64>::identity().is_symmetric());
+        assert!(Matrix2::<f64>::identity().is_diagonal());
+        assert!(Matrix2::<f64>::identity().is_invertible());
+
+        assert!(!A.is_identity());
+        assert!(!A.is_symmetric());
+        assert!(!A.is_diagonal());
+        assert!(A.is_invertible());
+
+        assert!(!C.is_identity());
+        assert!(C.is_symmetric());
+        assert!(!C.is_diagonal());
+        assert!(C.is_invertible());
+
+        assert!(Matrix2::from_value(6.0f64).is_diagonal());
+    }
+
+    #[test]
+    fn test_from_angle() {
+        // Rotate the vector (1, 0) by π/2 radians to the vector (0, 1)
+        let rot1 = Matrix2::from_angle(rad(0.5f64 * f64::consts::PI));
+        assert_approx_eq!(rot1 * Vector2::unit_x(), &Vector2::unit_y());
+
+        // Rotate the vector (-1, 0) by -π/2 radians to the vector (0, 1)
+        let rot2 = -rot1;
+        assert_approx_eq!(rot2 * -Vector2::unit_x(), &Vector2::unit_y());
+
+        // Rotate the vector (1, 1) by π radians to the vector (-1, -1)
+        let rot3: Matrix2<f64> = Matrix2::from_angle(rad(f64::consts::PI));
+        assert_approx_eq!(rot3 * Vector2::new(1.0, 1.0), &Vector2::new(-1.0, -1.0));
+    }
 }
 
 pub mod matrix3 {
     use cgmath::*;
 
-    pub static A: Matrix3<f64> = Matrix3 { x: Vector3 { x: 1.0f64, y: 4.0f64, z:  7.0f64 },
-                                           y: Vector3 { x: 2.0f64, y: 5.0f64, z:  8.0f64 },
-                                           z: Vector3 { x: 3.0f64, y: 6.0f64, z:  9.0f64 } };
-    pub static B: Matrix3<f64> = Matrix3 { x: Vector3 { x: 2.0f64, y: 5.0f64, z:  8.0f64 },
-                                           y: Vector3 { x: 3.0f64, y: 6.0f64, z:  9.0f64 },
-                                           z: Vector3 { x: 4.0f64, y: 7.0f64, z: 10.0f64 } };
-    pub static C: Matrix3<f64> = Matrix3 { x: Vector3 { x: 2.0f64, y: 4.0f64, z:  6.0f64 },
-                                           y: Vector3 { x: 0.0f64, y: 2.0f64, z:  4.0f64 },
-                                           z: Vector3 { x: 0.0f64, y: 0.0f64, z:  1.0f64 } };
-    pub static D: Matrix3<f64> = Matrix3 { x: Vector3 { x: 3.0f64, y: 2.0f64, z:  1.0f64 },
-                                           y: Vector3 { x: 2.0f64, y: 3.0f64, z:  2.0f64 },
-                                           z: Vector3 { x: 1.0f64, y: 2.0f64, z:  3.0f64 } };
+    const A: Matrix3<f64> = Matrix3 { x: Vector3 { x: 1.0f64, y: 4.0f64, z:  7.0f64 },
+                                      y: Vector3 { x: 2.0f64, y: 5.0f64, z:  8.0f64 },
+                                      z: Vector3 { x: 3.0f64, y: 6.0f64, z:  9.0f64 } };
+    const B: Matrix3<f64> = Matrix3 { x: Vector3 { x: 2.0f64, y: 5.0f64, z:  8.0f64 },
+                                      y: Vector3 { x: 3.0f64, y: 6.0f64, z:  9.0f64 },
+                                      z: Vector3 { x: 4.0f64, y: 7.0f64, z: 10.0f64 } };
+    const C: Matrix3<f64> = Matrix3 { x: Vector3 { x: 2.0f64, y: 4.0f64, z:  6.0f64 },
+                                      y: Vector3 { x: 0.0f64, y: 2.0f64, z:  4.0f64 },
+                                      z: Vector3 { x: 0.0f64, y: 0.0f64, z:  1.0f64 } };
+    const D: Matrix3<f64> = Matrix3 { x: Vector3 { x: 3.0f64, y: 2.0f64, z:  1.0f64 },
+                                      y: Vector3 { x: 2.0f64, y: 3.0f64, z:  2.0f64 },
+                                      z: Vector3 { x: 1.0f64, y: 2.0f64, z:  3.0f64 } };
 
-    pub static V: Vector3<f64> = Vector3 { x: 1.0f64, y: 2.0f64, z:  3.0f64 };
-    pub static F: f64 = 0.5;
+    const V: Vector3<f64> = Vector3 { x: 1.0f64, y: 2.0f64, z:  3.0f64 };
+    const F: f64 = 0.5;
+
+    #[test]
+    fn test_neg() {
+        assert_eq!(-A,
+                   Matrix3::new(-1.0f64, -4.0f64, -7.0f64,
+                                -2.0f64, -5.0f64, -8.0f64,
+                                -3.0f64, -6.0f64, -9.0f64));
+    }
+
+    #[test]
+    fn test_mul_scalar() {
+        assert_eq!(A * F,
+                   Matrix3::new(0.5f64, 2.0f64, 3.5f64,
+                                1.0f64, 2.5f64, 4.0f64,
+                                1.5f64, 3.0f64, 4.5f64));
+    }
+
+    #[test]
+    fn test_add_matrix() {
+        assert_eq!(A + B,
+                   Matrix3::new(3.0f64,  9.0f64, 15.0f64,
+                                5.0f64, 11.0f64, 17.0f64,
+                                7.0f64, 13.0f64, 19.0f64));
+    }
+
+    #[test]
+    fn test_sub_matrix() {
+        assert_eq!(A - B,
+                   Matrix3::new(-1.0f64, -1.0f64, -1.0f64,
+                                -1.0f64, -1.0f64, -1.0f64,
+                                -1.0f64, -1.0f64, -1.0f64));
+    }
+
+    #[test]
+    fn test_mul_vector() {
+        assert_eq!(A * V, Vector3::new(14.0f64, 32.0f64, 50.0f64));
+    }
+
+    #[test]
+    fn test_mul_matrix() {
+        assert_eq!(A * B,
+                   Matrix3::new(36.0f64,  81.0f64, 126.0f64,
+                                42.0f64,  96.0f64, 150.0f64,
+                                48.0f64, 111.0f64, 174.0f64));
+
+        assert_eq!(A * B, &A * &B);
+    }
+
+    #[test]
+    fn test_determinant() {;
+        assert_eq!(A.determinant(), 0.0f64);
+    }
+
+    #[test]
+    fn test_trace() {
+        assert_eq!(A.trace(), 15.0f64);
+    }
+
+    #[test]
+    fn test_transpose() {
+        assert_eq!(A.transpose(),
+                   Matrix3::<f64>::new(1.0f64, 2.0f64, 3.0f64,
+                                       4.0f64, 5.0f64, 6.0f64,
+                                       7.0f64, 8.0f64, 9.0f64));
+    }
+
+    #[test]
+    fn test_transpose_self() {
+        let mut mut_a = A;
+        mut_a.transpose_self();
+        assert_eq!(mut_a, A.transpose());
+    }
+
+    #[test]
+    fn test_invert() {
+        assert!(Matrix3::<f64>::identity().invert().unwrap().is_identity());
+
+        assert_eq!(A.invert(), None);
+
+        assert_eq!(C.invert().unwrap(),
+                   Matrix3::new(0.5f64, -1.0f64,  1.0f64,
+                                0.0f64,  0.5f64, -2.0f64,
+                                0.0f64,  0.0f64,  1.0f64));
+    }
+
+    #[test]
+    fn test_invert_self() {
+        let mut mut_c = C;
+        mut_c.invert_self();
+        assert_eq!(mut_c, C.invert().unwrap());
+    }
+
+    #[test]
+    fn test_predicates() {
+        assert!(Matrix3::<f64>::identity().is_identity());
+        assert!(Matrix3::<f64>::identity().is_symmetric());
+        assert!(Matrix3::<f64>::identity().is_diagonal());
+        assert!(Matrix3::<f64>::identity().is_invertible());
+
+        assert!(!A.is_identity());
+        assert!(!A.is_symmetric());
+        assert!(!A.is_diagonal());
+        assert!(!A.is_invertible());
+
+        assert!(!D.is_identity());
+        assert!(D.is_symmetric());
+        assert!(!D.is_diagonal());
+        assert!(D.is_invertible());
+
+        assert!(Matrix3::from_value(6.0f64).is_diagonal());
+    }
+
+    mod from_axis_x {
+        use cgmath::*;
+
+        fn check_from_axis_angle_x(pitch: Rad<f32>) {
+            let found = Matrix3::from_angle_x(pitch);
+            let expected = Matrix3::from_euler(pitch, rad(0.0), rad(0.0));
+            assert_approx_eq_eps!(found, expected, 0.001);
+        }
+
+        #[test] fn test_zero()      { check_from_axis_angle_x(rad(0.0)); }
+        #[test] fn test_pos_1()     { check_from_axis_angle_x(rad(1.0)); }
+        #[test] fn test_neg_1()     { check_from_axis_angle_x(rad(-1.0)); }
+    }
+
+    mod from_axis_y {
+        use cgmath::*;
+
+        fn check_from_axis_angle_y(yaw: Rad<f32>) {
+            let found = Matrix3::from_angle_y(yaw);
+            let expected = Matrix3::from_euler(rad(0.0), yaw, rad(0.0));
+            assert_approx_eq_eps!(found, expected, 0.001);
+        }
+
+        #[test] fn test_zero()      { check_from_axis_angle_y(rad(0.0)); }
+        #[test] fn test_pos_1()     { check_from_axis_angle_y(rad(1.0)); }
+        #[test] fn test_neg_1()     { check_from_axis_angle_y(rad(-1.0)); }
+    }
+
+    mod from_axis_z {
+        use cgmath::*;
+
+        fn check_from_axis_angle_z(roll: Rad<f32>) {
+            let found = Matrix3::from_angle_z(roll);
+            let expected = Matrix3::from_euler(rad(0.0), rad(0.0), roll);
+            assert_approx_eq_eps!(found, expected, 0.001);
+        }
+
+        #[test] fn test_zero()      { check_from_axis_angle_z(rad(0.0)); }
+        #[test] fn test_pos_1()     { check_from_axis_angle_z(rad(1.0)); }
+        #[test] fn test_neg_1()     { check_from_axis_angle_z(rad(-1.0)); }
+    }
+
+    mod from_axis_angle {
+        mod axis_x {
+            use cgmath::*;
+
+            fn check_from_axis_angle_x(pitch: Rad<f32>) {
+                let found = Matrix3::from_axis_angle(Vector3::unit_x(), pitch);
+                let expected = Matrix3::from_euler(pitch, rad(0.0), rad(0.0));
+                assert_approx_eq_eps!(found, expected, 0.001);
+            }
+
+            #[test] fn test_zero()      { check_from_axis_angle_x(rad(0.0)); }
+            #[test] fn test_pos_1()     { check_from_axis_angle_x(rad(1.0)); }
+            #[test] fn test_neg_1()     { check_from_axis_angle_x(rad(-1.0)); }
+        }
+
+        mod axis_y {
+            use cgmath::*;
+
+            fn check_from_axis_angle_y(yaw: Rad<f32>) {
+                let found = Matrix3::from_axis_angle(Vector3::unit_y(), yaw);
+                let expected = Matrix3::from_euler(rad(0.0), yaw, rad(0.0));
+                assert_approx_eq_eps!(found, expected, 0.001);
+            }
+
+            #[test] fn test_zero()      { check_from_axis_angle_y(rad(0.0)); }
+            #[test] fn test_pos_1()     { check_from_axis_angle_y(rad(1.0)); }
+            #[test] fn test_neg_1()     { check_from_axis_angle_y(rad(-1.0)); }
+        }
+
+        mod axis_z {
+            use cgmath::*;
+
+            fn check_from_axis_angle_z(roll: Rad<f32>) {
+                let found = Matrix3::from_axis_angle(Vector3::unit_z(), roll);
+                let expected = Matrix3::from_euler(rad(0.0), rad(0.0), roll);
+                assert_approx_eq_eps!(found, expected, 0.001);
+            }
+
+            #[test] fn test_zero()      { check_from_axis_angle_z(rad(0.0)); }
+            #[test] fn test_pos_1()     { check_from_axis_angle_z(rad(1.0)); }
+            #[test] fn test_neg_1()     { check_from_axis_angle_z(rad(-1.0)); }
+        }
+    }
 }
 
 pub mod matrix4 {
     use cgmath::*;
 
-    pub static A: Matrix4<f64> = Matrix4 { x: Vector4 { x: 1.0f64, y: 5.0f64, z:  9.0f64, w: 13.0f64 },
-                                           y: Vector4 { x: 2.0f64, y: 6.0f64, z: 10.0f64, w: 14.0f64 },
-                                           z: Vector4 { x: 3.0f64, y: 7.0f64, z: 11.0f64, w: 15.0f64 },
-                                           w: Vector4 { x: 4.0f64, y: 8.0f64, z: 12.0f64, w: 16.0f64 } };
-    pub static B: Matrix4<f64> = Matrix4 { x: Vector4 { x: 2.0f64, y: 6.0f64, z: 10.0f64, w: 14.0f64 },
-                                           y: Vector4 { x: 3.0f64, y: 7.0f64, z: 11.0f64, w: 15.0f64 },
-                                           z: Vector4 { x: 4.0f64, y: 8.0f64, z: 12.0f64, w: 16.0f64 },
-                                           w: Vector4 { x: 5.0f64, y: 9.0f64, z: 13.0f64, w: 17.0f64 } };
-    pub static C: Matrix4<f64> = Matrix4 { x: Vector4 { x: 3.0f64, y: 2.0f64, z:  1.0f64, w:  1.0f64 },
-                                           y: Vector4 { x: 2.0f64, y: 3.0f64, z:  2.0f64, w:  2.0f64 },
-                                           z: Vector4 { x: 1.0f64, y: 2.0f64, z:  3.0f64, w:  3.0f64 },
-                                           w: Vector4 { x: 0.0f64, y: 1.0f64, z:  1.0f64, w:  0.0f64 } };
-    pub static D: Matrix4<f64> = Matrix4 { x: Vector4 { x: 4.0f64, y: 3.0f64, z:  2.0f64, w:  1.0f64 },
-                                           y: Vector4 { x: 3.0f64, y: 4.0f64, z:  3.0f64, w:  2.0f64 },
-                                           z: Vector4 { x: 2.0f64, y: 3.0f64, z:  4.0f64, w:  3.0f64 },
-                                           w: Vector4 { x: 1.0f64, y: 2.0f64, z:  3.0f64, w:  4.0f64 } };
+    const A: Matrix4<f64> = Matrix4 { x: Vector4 { x: 1.0f64, y: 5.0f64, z:  9.0f64, w: 13.0f64 },
+                                      y: Vector4 { x: 2.0f64, y: 6.0f64, z: 10.0f64, w: 14.0f64 },
+                                      z: Vector4 { x: 3.0f64, y: 7.0f64, z: 11.0f64, w: 15.0f64 },
+                                      w: Vector4 { x: 4.0f64, y: 8.0f64, z: 12.0f64, w: 16.0f64 } };
+    const B: Matrix4<f64> = Matrix4 { x: Vector4 { x: 2.0f64, y: 6.0f64, z: 10.0f64, w: 14.0f64 },
+                                      y: Vector4 { x: 3.0f64, y: 7.0f64, z: 11.0f64, w: 15.0f64 },
+                                      z: Vector4 { x: 4.0f64, y: 8.0f64, z: 12.0f64, w: 16.0f64 },
+                                      w: Vector4 { x: 5.0f64, y: 9.0f64, z: 13.0f64, w: 17.0f64 } };
+    const C: Matrix4<f64> = Matrix4 { x: Vector4 { x: 3.0f64, y: 2.0f64, z:  1.0f64, w:  1.0f64 },
+                                      y: Vector4 { x: 2.0f64, y: 3.0f64, z:  2.0f64, w:  2.0f64 },
+                                      z: Vector4 { x: 1.0f64, y: 2.0f64, z:  3.0f64, w:  3.0f64 },
+                                      w: Vector4 { x: 0.0f64, y: 1.0f64, z:  1.0f64, w:  0.0f64 } };
+    const D: Matrix4<f64> = Matrix4 { x: Vector4 { x: 4.0f64, y: 3.0f64, z:  2.0f64, w:  1.0f64 },
+                                      y: Vector4 { x: 3.0f64, y: 4.0f64, z:  3.0f64, w:  2.0f64 },
+                                      z: Vector4 { x: 2.0f64, y: 3.0f64, z:  4.0f64, w:  3.0f64 },
+                                      w: Vector4 { x: 1.0f64, y: 2.0f64, z:  3.0f64, w:  4.0f64 } };
 
-    pub static V: Vector4<f64> = Vector4 { x: 1.0f64, y: 2.0f64, z: 3.0f64, w: 4.0f64 };
-    pub static F: f64 = 0.5;
-}
-
-#[test]
-fn test_neg() {
-    assert_eq!(-matrix2::A,
-               Matrix2::new(-1.0f64, -3.0f64,
-                            -2.0f64, -4.0f64));
-
-    assert_eq!(-matrix3::A,
-               Matrix3::new(-1.0f64, -4.0f64, -7.0f64,
-                            -2.0f64, -5.0f64, -8.0f64,
-                            -3.0f64, -6.0f64, -9.0f64));
-
-    assert_eq!(-matrix4::A,
-               Matrix4::new(-1.0f64, -5.0f64,  -9.0f64, -13.0f64,
-                            -2.0f64, -6.0f64, -10.0f64, -14.0f64,
-                            -3.0f64, -7.0f64, -11.0f64, -15.0f64,
-                            -4.0f64, -8.0f64, -12.0f64, -16.0f64));
-}
-
-#[test]
-fn test_mul_scalar() {
-    assert_eq!(matrix2::A * matrix2::F,
-               Matrix2::new(0.5f64, 1.5f64,
-                            1.0f64, 2.0f64));
-
-    assert_eq!(matrix3::A * matrix3::F,
-               Matrix3::new(0.5f64, 2.0f64, 3.5f64,
-                            1.0f64, 2.5f64, 4.0f64,
-                            1.5f64, 3.0f64, 4.5f64));
-
-    assert_eq!(matrix4::A * matrix4::F,
-               Matrix4::new(0.5f64, 2.5f64, 4.5f64, 6.5f64,
-                            1.0f64, 3.0f64, 5.0f64, 7.0f64,
-                            1.5f64, 3.5f64, 5.5f64, 7.5f64,
-                            2.0f64, 4.0f64, 6.0f64, 8.0f64));
-}
-
-#[test]
-fn test_add_matrix() {
-    assert_eq!(matrix2::A + matrix2::B,
-               Matrix2::new(3.0f64, 7.0f64,
-                            5.0f64, 9.0f64));
-
-    assert_eq!(matrix3::A + matrix3::B,
-               Matrix3::new(3.0f64,  9.0f64, 15.0f64,
-                            5.0f64, 11.0f64, 17.0f64,
-                            7.0f64, 13.0f64, 19.0f64));
-
-    assert_eq!(matrix4::A + matrix4::B,
-               Matrix4::new(3.0f64, 11.0f64, 19.0f64, 27.0f64,
-                            5.0f64, 13.0f64, 21.0f64, 29.0f64,
-                            7.0f64, 15.0f64, 23.0f64, 31.0f64,
-                            9.0f64, 17.0f64, 25.0f64, 33.0f64));
-}
-
-#[test]
-fn test_sub_matrix() {
-    assert_eq!(matrix2::A - matrix2::B,
-               Matrix2::new(-1.0f64, -1.0f64,
-                            -1.0f64, -1.0f64));
-
-    assert_eq!(matrix3::A - matrix3::B,
-               Matrix3::new(-1.0f64, -1.0f64, -1.0f64,
-                            -1.0f64, -1.0f64, -1.0f64,
-                            -1.0f64, -1.0f64, -1.0f64));
-
-    assert_eq!(matrix4::A - matrix4::B,
-               Matrix4::new(-1.0f64, -1.0f64, -1.0f64, -1.0f64,
-                            -1.0f64, -1.0f64, -1.0f64, -1.0f64,
-                            -1.0f64, -1.0f64, -1.0f64, -1.0f64,
-                            -1.0f64, -1.0f64, -1.0f64, -1.0f64));
-}
-
-#[test]
-fn test_mul_vector() {
-    assert_eq!(matrix2::A * matrix2::V, Vector2::new(5.0f64, 11.0f64));
-    assert_eq!(matrix3::A * matrix3::V, Vector3::new(14.0f64, 32.0f64, 50.0f64));
-    assert_eq!(matrix4::A * matrix4::V, Vector4::new(30.0f64, 70.0f64, 110.0f64, 150.0f64));
-}
-
-#[test]
-fn test_mul_matrix() {
-    assert_eq!(matrix2::A * matrix2::B,
-               Matrix2::new(10.0f64, 22.0f64,
-                            13.0f64, 29.0f64));
-    assert_eq!(matrix3::A * matrix3::B,
-               Matrix3::new(36.0f64,  81.0f64, 126.0f64,
-                            42.0f64,  96.0f64, 150.0f64,
-                            48.0f64, 111.0f64, 174.0f64));
-    assert_eq!(matrix4::A * matrix4::B,
-               Matrix4::new(100.0f64, 228.0f64, 356.0f64, 484.0f64,
-                            110.0f64, 254.0f64, 398.0f64, 542.0f64,
-                            120.0f64, 280.0f64, 440.0f64, 600.0f64,
-                            130.0f64, 306.0f64, 482.0f64, 658.0f64));
-
-    assert_eq!(matrix2::A * matrix2::B, &matrix2::A * &matrix2::B);
-    assert_eq!(matrix3::A * matrix3::B, &matrix3::A * &matrix3::B);
-    assert_eq!(matrix4::A * matrix4::B, &matrix4::A * &matrix4::B);
-}
-
-#[test]
-fn test_determinant() {
-    assert_eq!(matrix2::A.determinant(), -2.0f64);
-    assert_eq!(matrix3::A.determinant(), 0.0f64);
-    assert_eq!(matrix4::A.determinant(), 0.0f64);
-}
-
-#[test]
-fn test_trace() {
-    assert_eq!(matrix2::A.trace(), 5.0f64);
-    assert_eq!(matrix3::A.trace(), 15.0f64);
-    assert_eq!(matrix4::A.trace(), 34.0f64);
-}
-
-#[test]
-fn test_transpose() {
-    // Matrix2
-    assert_eq!(matrix2::A.transpose(),
-               Matrix2::<f64>::new(1.0f64, 2.0f64,
-                                   3.0f64, 4.0f64));
-    let mut mut_a = matrix2::A;
-    mut_a.transpose_self();
-    assert_eq!(mut_a, matrix2::A.transpose());
-
-    // Matrix3
-    assert_eq!(matrix3::A.transpose(),
-               Matrix3::<f64>::new(1.0f64, 2.0f64, 3.0f64,
-                                   4.0f64, 5.0f64, 6.0f64,
-                                   7.0f64, 8.0f64, 9.0f64));
-    let mut mut_a = matrix3::A;
-    mut_a.transpose_self();
-    assert_eq!(mut_a, matrix3::A.transpose());
-
-    // Matrix4
-    assert_eq!(matrix4::A.transpose(),
-               Matrix4::<f64>::new( 1.0f64,  2.0f64,  3.0f64,  4.0f64,
-                                    5.0f64,  6.0f64,  7.0f64,  8.0f64,
-                                    9.0f64, 10.0f64, 11.0f64, 12.0f64,
-                                   13.0f64, 14.0f64, 15.0f64, 16.0f64));
-    let mut mut_a = matrix4::A;
-    mut_a.transpose_self();
-    assert_eq!(mut_a, matrix4::A.transpose());
-}
-
-#[test]
-fn test_invert() {
-    // Matrix2
-    assert!(Matrix2::<f64>::identity().invert().unwrap().is_identity());
-
-    assert_eq!(matrix2::A.invert().unwrap(),
-               Matrix2::new(-2.0f64,  1.5f64,
-                             1.0f64, -0.5f64));
-    assert!(Matrix2::new(0.0f64, 2.0f64,
-                         0.0f64, 5.0f64).invert().is_none());
-    let mut mut_a = matrix2::A;
-    mut_a.invert_self();
-    assert_eq!(mut_a, matrix2::A.invert().unwrap());
-
-    // Matrix3
-    assert!(Matrix3::<f64>::identity().invert().unwrap().is_identity());
-
-    assert_eq!(matrix3::A.invert(), None);
-
-    assert_eq!(matrix3::C.invert().unwrap(),
-               Matrix3::new(0.5f64, -1.0f64,  1.0f64,
-                            0.0f64,  0.5f64, -2.0f64,
-                            0.0f64,  0.0f64,  1.0f64));
-    let mut mut_c = matrix3::C;
-    mut_c.invert_self();
-    assert_eq!(mut_c, matrix3::C.invert().unwrap());
-
-    // Matrix4
-    assert!(Matrix4::<f64>::identity().invert().unwrap().is_identity());
-
-    assert!(matrix4::C.invert().unwrap().approx_eq(&(
-            Matrix4::new( 5.0f64, -4.0f64,  1.0f64,  0.0f64,
-                         -4.0f64,  8.0f64, -4.0f64,  0.0f64,
-                          4.0f64, -8.0f64,  4.0f64,  8.0f64,
-                         -3.0f64,  4.0f64,  1.0f64, -8.0f64) * 0.125f64)));
-    let mut mut_c = matrix4::C;
-    mut_c.invert_self();
-    assert_eq!(mut_c, matrix4::C.invert().unwrap());
-
-    let mat_c = Matrix4::new(-0.131917f64, -0.76871f64,   0.625846f64, 0.0f64,
-                             -0.,        0.631364f64,  0.775487f64, 0.0f64,
-                             -0.991261f64,  0.1023f64,   -0.083287f64, 0.0f64,
-                              0.,       -1.262728f64, -1.550973f64, 1.0f64);
-    assert!((mat_c.invert().unwrap() * mat_c).is_identity());
-
-    let mat_d = Matrix4::new( 0.065455f64, -0.720002f64,  0.690879f64, 0.0f64,
-                             -0.,        0.692364f64,  0.721549f64, 0.0f64,
-                             -0.997856f64, -0.047229f64,  0.045318f64, 0.0f64,
-                              0.,       -1.384727f64, -1.443098f64, 1.0f64);
-    assert!((mat_d.invert().unwrap() * mat_d).is_identity());
-
-    let mat_e = Matrix4::new( 0.409936f64,  0.683812f64, -0.603617f64, 0.0f64,
-                              0.,        0.661778f64,  0.7497f64,   0.0f64,
-                              0.912114f64, -0.307329f64,  0.271286f64, 0.0f64,
-                             -0.,       -1.323555f64, -1.499401f64, 1.0f64);
-    assert!((mat_e.invert().unwrap() * mat_e).is_identity());
-
-    let mat_f = Matrix4::new(-0.160691f64, -0.772608f64,  0.614211f64, 0.0f64,
-                             -0.,        0.622298f64,  0.78278f64,  0.0f64,
-                             -0.987005f64,  0.125786f64, -0.099998f64, 0.0f64,
-                              0.,       -1.244597f64, -1.565561f64, 1.0f64);
-    assert!((mat_f.invert().unwrap() * mat_f).is_identity());
-}
-
-#[test]
-fn test_from_translation() {
-    let mat = Matrix4::from_translation(Vector3::new(1.0f64, 2.0f64, 3.0f64));
-    let vertex = Vector4::new(0.0f64, 0.0f64, 0.0f64, 1.0f64);
-    let res = mat * vertex;
-    assert_eq!(res, Vector4::new(1., 2., 3., 1.));
-}
-
-#[test]
-fn test_predicates() {
-    // Matrix2
-
-    assert!(Matrix2::<f64>::identity().is_identity());
-    assert!(Matrix2::<f64>::identity().is_symmetric());
-    assert!(Matrix2::<f64>::identity().is_diagonal());
-    assert!(Matrix2::<f64>::identity().is_invertible());
-
-    assert!(!matrix2::A.is_identity());
-    assert!(!matrix2::A.is_symmetric());
-    assert!(!matrix2::A.is_diagonal());
-    assert!(matrix2::A.is_invertible());
-
-    assert!(!matrix2::C.is_identity());
-    assert!(matrix2::C.is_symmetric());
-    assert!(!matrix2::C.is_diagonal());
-    assert!(matrix2::C.is_invertible());
-
-    assert!(Matrix2::from_value(6.0f64).is_diagonal());
-
-    // Matrix3
-
-    assert!(Matrix3::<f64>::identity().is_identity());
-    assert!(Matrix3::<f64>::identity().is_symmetric());
-    assert!(Matrix3::<f64>::identity().is_diagonal());
-    assert!(Matrix3::<f64>::identity().is_invertible());
-
-    assert!(!matrix3::A.is_identity());
-    assert!(!matrix3::A.is_symmetric());
-    assert!(!matrix3::A.is_diagonal());
-    assert!(!matrix3::A.is_invertible());
-
-    assert!(!matrix3::D.is_identity());
-    assert!(matrix3::D.is_symmetric());
-    assert!(!matrix3::D.is_diagonal());
-    assert!(matrix3::D.is_invertible());
-
-    assert!(Matrix3::from_value(6.0f64).is_diagonal());
-
-    // Matrix4
-
-    assert!(Matrix4::<f64>::identity().is_identity());
-    assert!(Matrix4::<f64>::identity().is_symmetric());
-    assert!(Matrix4::<f64>::identity().is_diagonal());
-    assert!(Matrix4::<f64>::identity().is_invertible());
-
-    assert!(!matrix4::A.is_identity());
-    assert!(!matrix4::A.is_symmetric());
-    assert!(!matrix4::A.is_diagonal());
-    assert!(!matrix4::A.is_invertible());
-
-    assert!(!matrix4::D.is_identity());
-    assert!(matrix4::D.is_symmetric());
-    assert!(!matrix4::D.is_diagonal());
-    assert!(matrix4::D.is_invertible());
-
-    assert!(Matrix4::from_value(6.0f64).is_diagonal());
-}
-
-#[test]
-fn test_from_angle() {
-    // Rotate the vector (1, 0) by π/2 radians to the vector (0, 1)
-    let rot1 = Matrix2::from_angle(rad(0.5f64 * f64::consts::PI));
-    assert!((rot1 * Vector2::unit_x()).approx_eq(&Vector2::unit_y()));
-
-    // Rotate the vector (-1, 0) by -π/2 radians to the vector (0, 1)
-    let rot2 = -rot1;
-    assert!((rot2 * -Vector2::unit_x()).approx_eq(&Vector2::unit_y()));
-
-    // Rotate the vector (1, 1) by π radians to the vector (-1, -1)
-    let rot3: Matrix2<f64> = Matrix2::from_angle(rad(f64::consts::PI));
-    assert!((rot3 * Vector2::new(1.0, 1.0)).approx_eq(&Vector2::new(-1.0, -1.0)));
-}
-
-fn test_matrix3_into_quaternion_for_angles(x: Rad<f32>, y: Rad<f32>, z: Rad<f32>) {
-    let matrix3: Matrix3<f32> = Matrix3::from_euler(x, y, z);
-    let quaternion: Quaternion<f32> = matrix3.into();
-    let quaternion_matrix3: Matrix3<f32> = quaternion.into();
-    assert_approx_eq!(matrix3, quaternion_matrix3);
-}
-
-// The next 4 tests trigger each of the cases in the impl for
-// conversion from Matrix3 to Quaternion
-#[test]
-fn test_matrix3_into_quaternion_positive_trace()
-{
-    // trigger the case: trace >= S::zero()
-    test_matrix3_into_quaternion_for_angles(rad(0.0f32), rad(0.0), rad(0.0f32));
-}
-
-#[test]
-fn test_matrix3_into_quaternion_xx_maximum()
-{
-    // trigger the case: (mat[0][0] > mat[1][1]) && (mat[0][0] > mat[2][2])
-    test_matrix3_into_quaternion_for_angles(rad(2.0f32), rad(1.0), rad(-1.2f32));
-}
-
-#[test]
-fn test_matrix3_into_quaternion_yy_maximum()
-{
-    // trigger the case: mat[1][1] > mat[2][2]
-    test_matrix3_into_quaternion_for_angles(rad(2.0f32), rad(1.0), rad(3.0f32));
-}
-
-#[test]
-fn test_matrix3_into_quaternion_zz_maximum()
-{
-    // trigger the else case
-    test_matrix3_into_quaternion_for_angles(rad(1.0f32), rad(1.0), rad(3.0f32));
+    const V: Vector4<f64> = Vector4 { x: 1.0f64, y: 2.0f64, z: 3.0f64, w: 4.0f64 };
+    const F: f64 = 0.5;
+
+    #[test]
+    fn test_neg() {
+        assert_eq!(-A,
+                   Matrix4::new(-1.0f64, -5.0f64,  -9.0f64, -13.0f64,
+                                -2.0f64, -6.0f64, -10.0f64, -14.0f64,
+                                -3.0f64, -7.0f64, -11.0f64, -15.0f64,
+                                -4.0f64, -8.0f64, -12.0f64, -16.0f64));
+    }
+
+    #[test]
+    fn test_mul_scalar() {
+        assert_eq!(A * F,
+                   Matrix4::new(0.5f64, 2.5f64, 4.5f64, 6.5f64,
+                                1.0f64, 3.0f64, 5.0f64, 7.0f64,
+                                1.5f64, 3.5f64, 5.5f64, 7.5f64,
+                                2.0f64, 4.0f64, 6.0f64, 8.0f64));
+    }
+
+    #[test]
+    fn test_add_matrix() {
+        assert_eq!(A + B,
+                   Matrix4::new(3.0f64, 11.0f64, 19.0f64, 27.0f64,
+                                5.0f64, 13.0f64, 21.0f64, 29.0f64,
+                                7.0f64, 15.0f64, 23.0f64, 31.0f64,
+                                9.0f64, 17.0f64, 25.0f64, 33.0f64));
+    }
+
+    #[test]
+    fn test_sub_matrix() {
+        assert_eq!(A - B,
+                   Matrix4::new(-1.0f64, -1.0f64, -1.0f64, -1.0f64,
+                                -1.0f64, -1.0f64, -1.0f64, -1.0f64,
+                                -1.0f64, -1.0f64, -1.0f64, -1.0f64,
+                                -1.0f64, -1.0f64, -1.0f64, -1.0f64));
+    }
+
+    #[test]
+    fn test_mul_vector() {
+        assert_eq!(A * V, Vector4::new(30.0f64, 70.0f64, 110.0f64, 150.0f64));
+    }
+
+    #[test]
+    fn test_mul_matrix() {
+        assert_eq!(A * B,
+                   Matrix4::new(100.0f64, 228.0f64, 356.0f64, 484.0f64,
+                                110.0f64, 254.0f64, 398.0f64, 542.0f64,
+                                120.0f64, 280.0f64, 440.0f64, 600.0f64,
+                                130.0f64, 306.0f64, 482.0f64, 658.0f64));
+
+        assert_eq!(A * B, &A * &B);
+    }
+
+    #[test]
+    fn test_determinant() {
+        assert_eq!(A.determinant(), 0.0f64);
+    }
+
+    #[test]
+    fn test_trace() {
+        assert_eq!(A.trace(), 34.0f64);
+    }
+
+    #[test]
+    fn test_transpose() {
+        assert_eq!(A.transpose(),
+                   Matrix4::<f64>::new( 1.0f64,  2.0f64,  3.0f64,  4.0f64,
+                                        5.0f64,  6.0f64,  7.0f64,  8.0f64,
+                                        9.0f64, 10.0f64, 11.0f64, 12.0f64,
+                                       13.0f64, 14.0f64, 15.0f64, 16.0f64));
+    }
+
+    #[test]
+    fn test_transpose_self() {
+        let mut mut_a = A;
+        mut_a.transpose_self();
+        assert_eq!(mut_a, A.transpose());
+    }
+
+    #[test]
+    fn test_invert() {
+        assert!(Matrix4::<f64>::identity().invert().unwrap().is_identity());
+
+        assert!(C.invert().unwrap().approx_eq(&(
+                Matrix4::new( 5.0f64, -4.0f64,  1.0f64,  0.0f64,
+                             -4.0f64,  8.0f64, -4.0f64,  0.0f64,
+                              4.0f64, -8.0f64,  4.0f64,  8.0f64,
+                             -3.0f64,  4.0f64,  1.0f64, -8.0f64) * 0.125f64)));
+
+        let mat_c = Matrix4::new(-0.131917f64, -0.76871f64,   0.625846f64, 0.0f64,
+                                 -0.,        0.631364f64,  0.775487f64, 0.0f64,
+                                 -0.991261f64,  0.1023f64,   -0.083287f64, 0.0f64,
+                                  0.,       -1.262728f64, -1.550973f64, 1.0f64);
+        assert!((mat_c.invert().unwrap() * mat_c).is_identity());
+
+        let mat_d = Matrix4::new( 0.065455f64, -0.720002f64,  0.690879f64, 0.0f64,
+                                 -0.,        0.692364f64,  0.721549f64, 0.0f64,
+                                 -0.997856f64, -0.047229f64,  0.045318f64, 0.0f64,
+                                  0.,       -1.384727f64, -1.443098f64, 1.0f64);
+        assert!((mat_d.invert().unwrap() * mat_d).is_identity());
+
+        let mat_e = Matrix4::new( 0.409936f64,  0.683812f64, -0.603617f64, 0.0f64,
+                                  0.,        0.661778f64,  0.7497f64,   0.0f64,
+                                  0.912114f64, -0.307329f64,  0.271286f64, 0.0f64,
+                                 -0.,       -1.323555f64, -1.499401f64, 1.0f64);
+        assert!((mat_e.invert().unwrap() * mat_e).is_identity());
+
+        let mat_f = Matrix4::new(-0.160691f64, -0.772608f64,  0.614211f64, 0.0f64,
+                                 -0.,        0.622298f64,  0.78278f64,  0.0f64,
+                                 -0.987005f64,  0.125786f64, -0.099998f64, 0.0f64,
+                                  0.,       -1.244597f64, -1.565561f64, 1.0f64);
+        assert!((mat_f.invert().unwrap() * mat_f).is_identity());
+    }
+
+    #[test]
+    fn test_invert_self() {
+        let mut mut_c = C;
+        mut_c.invert_self();
+        assert_eq!(mut_c, C.invert().unwrap());
+    }
+
+    #[test]
+    fn test_predicates() {
+        assert!(Matrix4::<f64>::identity().is_identity());
+        assert!(Matrix4::<f64>::identity().is_symmetric());
+        assert!(Matrix4::<f64>::identity().is_diagonal());
+        assert!(Matrix4::<f64>::identity().is_invertible());
+
+        assert!(!A.is_identity());
+        assert!(!A.is_symmetric());
+        assert!(!A.is_diagonal());
+        assert!(!A.is_invertible());
+
+        assert!(!D.is_identity());
+        assert!(D.is_symmetric());
+        assert!(!D.is_diagonal());
+        assert!(D.is_invertible());
+
+        assert!(Matrix4::from_value(6.0f64).is_diagonal());
+    }
+
+    #[test]
+    fn test_from_translation() {
+        let mat = Matrix4::from_translation(Vector3::new(1.0f64, 2.0f64, 3.0f64));
+        let vertex = Vector4::new(0.0f64, 0.0f64, 0.0f64, 1.0f64);
+        let res = mat * vertex;
+        assert_eq!(res, Vector4::new(1., 2., 3., 1.));
+    }
+
+    mod from {
+        use cgmath::*;
+
+        #[test]
+        fn test_quaternion() {
+            let quaternion = Quaternion::new(2f32, 3f32, 4f32, 5f32);
+
+            let matrix_short = Matrix4::from(quaternion);
+
+            let matrix_long = Matrix3::from(quaternion);
+            let matrix_long = Matrix4::from(matrix_long);
+
+            assert_approx_eq!(matrix_short, matrix_long);
+        }
+    }
 }

tests/quaternion.rs

@@ -13,75 +13,71 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+#[macro_use]
 extern crate cgmath;
 
-use cgmath::{Matrix4, Matrix3};
-use cgmath::Quaternion;
+mod to_from_euler {
+    use std::f32;
 
-use cgmath::{Rad, rad, ApproxEq};
-use cgmath::Rotation3;
+    use cgmath::*;
 
-use std::f32;
+    fn check_euler(pitch: Rad<f32>, yaw: Rad<f32>, roll: Rad<f32>) {
+        let quat = Quaternion::from_euler(pitch, yaw, roll);
+        let (found_pitch, found_yaw, found_roll) = quat.to_euler();
 
-#[test]
-fn to_matrix4()
-{
-    let quaternion = Quaternion::new(2f32, 3f32, 4f32, 5f32);
-
-    let matrix_short: Matrix4<_> = quaternion.into();
-
-    let matrix_long: Matrix3<_> = quaternion.into();
-    let matrix_long: Matrix4<_> = matrix_long.into();
-
-    assert!(matrix_short == matrix_long);
-}
-
-#[test]
-fn to_and_from_quaternion()
-{
-    fn eq(a: (Rad<f32>, Rad<f32>, Rad<f32>), b: (Rad<f32>, Rad<f32>, Rad<f32>)) {
-        let (ax, ay, az) = a;
-        let (bx, by, bz) = b;
-        if !(ax.approx_eq_eps(&bx, &0.001) &&
-             ay.approx_eq_eps(&by, &0.001) &&
-             az.approx_eq_eps(&bz, &0.001)) {
-            panic!("{:?} != {:?}", a, b)
-        }
+        assert_approx_eq_eps!(pitch, found_pitch, 0.001);
+        assert_approx_eq_eps!(yaw, found_yaw, 0.001);
+        assert_approx_eq_eps!(roll, found_roll, 0.001);
     }
 
-    let hpi = f32::consts::FRAC_PI_2;
-
-    let zero: Quaternion<f32> = Rotation3::from_euler(rad(0f32), rad(0f32), rad(0f32));
-    eq((rad(0f32), rad(0f32), rad(0f32)), zero.to_euler());
-
-    let x_1: Quaternion<f32> = Rotation3::from_euler(rad(1f32), rad(0f32), rad(0f32));
-    eq((rad(1f32), rad(0f32), rad(0f32)), x_1.to_euler());
-
-    let y_1: Quaternion<f32> = Rotation3::from_euler(rad(0f32), rad(1f32), rad(0f32));
-    eq((rad(0f32), rad(1f32), rad(0f32)), y_1.to_euler());
-
-    let z_1: Quaternion<f32> = Rotation3::from_euler(rad(0f32), rad(0f32), rad(1f32));
-    eq((rad(0f32), rad(0f32), rad(1f32)), z_1.to_euler());
-
-    let x_n1: Quaternion<f32> = Rotation3::from_euler(rad(-1f32), rad(0f32), rad(0f32));
-    eq((rad(-1f32), rad(0f32), rad(0f32)), x_n1.to_euler());
-
-    let y_n1: Quaternion<f32> = Rotation3::from_euler(rad(0f32), rad(-1f32), rad(0f32));
-    eq((rad(0f32), rad(-1f32), rad(0f32)), y_n1.to_euler());
-
-    let z_n1: Quaternion<f32> = Rotation3::from_euler(rad(0f32), rad(0f32), rad(-1f32));
-    eq((rad(0f32), rad(0f32), rad(-1f32)), z_n1.to_euler());
-
-    let xzy_1: Quaternion<f32> = Rotation3::from_euler(rad(1f32), rad(1f32), rad(1f32));
-    eq((rad(1f32), rad(1f32), rad(1f32)), xzy_1.to_euler());
-
-    let xzy_n1: Quaternion<f32> = Rotation3::from_euler(rad(-1f32), rad(-1f32), rad(-1f32));
-    eq((rad(-1f32), rad(-1f32), rad(-1f32)), xzy_n1.to_euler());
-
-    let xzy_hp: Quaternion<f32> = Rotation3::from_euler(rad(0f32), rad(hpi), rad(1f32));
-    eq((rad(0f32), rad(hpi), rad(1f32)), xzy_hp.to_euler());
-
-    let xzy_nhp: Quaternion<f32> = Rotation3::from_euler(rad(0f32), rad(-hpi), rad(1f32));
-    eq((rad(0f32), rad(-hpi), rad(1f32)), xzy_nhp.to_euler());
+    const HPI: f32 = f32::consts::FRAC_PI_2;
 
+    #[test] fn test_zero()                  { check_euler(rad(0f32), rad(0f32), rad(0f32)); }
+    #[test] fn test_yaw_pos_1()             { check_euler(rad(0f32), rad(1f32), rad(0f32)); }
+    #[test] fn test_yaw_neg_1()             { check_euler(rad(0f32), rad(-1f32), rad(0f32)); }
+    #[test] fn test_pitch_pos_1()           { check_euler(rad(1f32), rad(0f32), rad(0f32)); }
+    #[test] fn test_pitch_neg_1()           { check_euler(rad(-1f32), rad(0f32), rad(0f32)); }
+    #[test] fn test_roll_pos_1()            { check_euler(rad(0f32), rad(0f32), rad(1f32)); }
+    #[test] fn test_roll_neg_1()            { check_euler(rad(0f32), rad(0f32), rad(-1f32)); }
+    #[test] fn test_pitch_yaw_roll_pos_1()  { check_euler(rad(1f32), rad(1f32), rad(1f32)); }
+    #[test] fn test_pitch_yaw_roll_neg_1()  { check_euler(rad(-1f32), rad(-1f32), rad(-1f32)); }
+    #[test] fn test_pitch_yaw_roll_pos_hp() { check_euler(rad(0f32), rad(HPI), rad(1f32)); }
+    #[test] fn test_pitch_yaw_roll_neg_hp() { check_euler(rad(0f32), rad(-HPI), rad(1f32)); }
+}
+
+mod from {
+    mod matrix3 {
+        use cgmath::*;
+
+        fn check_with_euler(x: Rad<f32>, y: Rad<f32>, z: Rad<f32>) {
+            let matrix3 = Matrix3::from_euler(x, y, z);
+            let quaternion = Quaternion::from(matrix3);
+            let quaternion_matrix3 = Matrix3::from(quaternion);
+            assert_approx_eq!(matrix3, quaternion_matrix3);
+        }
+
+        // triggers: trace >= S::zero()
+        #[test]
+        fn test_positive_trace() {
+            check_with_euler(rad(0.0f32), rad(0.0), rad(0.0f32));
+        }
+
+        // triggers: (mat[0][0] > mat[1][1]) && (mat[0][0] > mat[2][2])
+        #[test]
+        fn test_xx_maximum() {
+            check_with_euler(rad(2.0f32), rad(1.0), rad(-1.2f32));
+        }
+
+        // triggers: mat[1][1] > mat[2][2]
+        #[test]
+        fn test_yy_maximum() {
+            check_with_euler(rad(2.0f32), rad(1.0), rad(3.0f32));
+        }
+
+        // base case
+        #[test]
+        fn test_zz_maximum() {
+            check_with_euler(rad(1.0f32), rad(1.0), rad(3.0f32));
+        }
+    }
 }