Add unit tests for Quaternion::createForX/Y/Z

Confirm that the generated Quaternion contains the values derived from the
half-angle, and is equal to that returned from createForMatrix() with the
equivalent rotation matrix.

libs/math/Quaternion.h

@@ -42,7 +42,7 @@ class Quaternion :
 	 */
 	static Quaternion createForUnitVectors(const Vector3& from, const Vector3& to);
 
-	/** 
+	/**
 	 * Constructs a rotation quaternion for the given euler angles.
 	 * Each component of the given vector refers to an angle (in degrees)
 	 * of one of the x-/y-/z-axis.
@@ -54,7 +54,7 @@ class Quaternion :
 	 */
 	static Quaternion createForAxisAngle(const Vector3& axis, double angle);
 
-	/** 
+	/**
 	 * Constructs a rotation quaternion about a given axis.
 	 */
 	static Quaternion createForX(double angle);
@@ -227,3 +227,10 @@ inline Vector3 Quaternion::transformPoint(const Vector3& point) const
 
 const double c_half_sqrt2 = 0.70710678118654752440084436210485;
 const float c_half_sqrt2f = static_cast<float>(c_half_sqrt2);
+
+/// Stream insertion for Quaternion
+inline std::ostream& operator<< (std::ostream& s, const Quaternion& q)
+{
+    return s << "Quaternion(x=" << q.x() << ", y=" << q.y() << ", z=" << q.z()
+             << ", w=" << q.w() << ")";
+}

test/math/Quaternion.cpp

@@ -1,10 +1,53 @@
 #include "gtest/gtest.h"
 
 #include "math/Quaternion.h"
+#include "math/Matrix4.h"
 
 namespace test
 {
 
+// Fuzzy equality assertion for Quaternions
+void expectNear(const Quaternion& q1, const Quaternion& q2)
+{
+    EXPECT_DOUBLE_EQ(q1.x(), q2.x());
+    EXPECT_DOUBLE_EQ(q1.y(), q2.y());
+    EXPECT_DOUBLE_EQ(q1.z(), q2.z());
+    EXPECT_DOUBLE_EQ(q1.w(), q2.w());
+}
+
+TEST(MathTest, QuaternionForXRotation)
+{
+    math::Degrees angle(45);
+    Quaternion xRot = Quaternion::createForX(angle.asRadians());
+
+    expectNear(xRot, Quaternion(sin(angle.asRadians() / 2), 0, 0,
+                                cos(angle.asRadians() / 2)));
+    expectNear(xRot,
+               Quaternion::createForMatrix(Matrix4::getRotationAboutX(angle)));
+}
+
+TEST(MathTest, QuaternionForYRotation)
+{
+    math::Degrees angle(60);
+    Quaternion yRot = Quaternion::createForY(angle.asRadians());
+
+    expectNear(yRot, Quaternion(0, sin(angle.asRadians() / 2), 0,
+                                cos(angle.asRadians() / 2)));
+    expectNear(yRot,
+               Quaternion::createForMatrix(Matrix4::getRotationAboutY(angle)));
+}
+
+TEST(MathTest, QuaternionForZRotation)
+{
+    math::Degrees angle(75);
+    Quaternion zRot = Quaternion::createForZ(angle.asRadians());
+
+    expectNear(zRot, Quaternion(0, 0, sin(angle.asRadians() / 2),
+                                cos(angle.asRadians() / 2)));
+    expectNear(zRot,
+               Quaternion::createForMatrix(Matrix4::getRotationAboutZ(angle)));
+}
+
 TEST(MathTest, QuaternionMultiplication)
 {
     Quaternion q1(3, 5, 7, 11);