Add tests for inverted rotations

tests/rotation.rs

@@ -0,0 +1,43 @@
+// Copyright 2015 The CGMath Developers. For a full listing of the authors,
+// refer to the Cargo.toml file at the top-level directory of this distribution.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+extern crate cgmath;
+
+use cgmath::*;
+
+mod rotation {
+    use super::cgmath::*;
+
+    pub fn a2<R: Rotation2<f64>>() -> R {
+        Rotation2::from_angle(deg(30.0).to_rad())
+    }
+
+    pub fn a3<R: Rotation3<f64>>() -> R {
+        let axis = Vector3::new(1.0, 1.0, 0.0).normalize();
+        Rotation3::from_axis_angle(&axis, deg(30.0).to_rad())
+    }
+}
+
+#[test]
+fn test_invert_basis2() {
+    let a: Basis2<_> = rotation::a2();
+    assert!(a.concat(&a.invert()).as_matrix2().is_identity());
+}
+
+#[test]
+fn test_invert_basis3() {
+    let a: Basis3<_> = rotation::a3();
+    assert!(a.concat(&a.invert()).as_matrix3().is_identity());
+}