Adding some tests for the matrix_helpers.hpp file.

matrix.xcodeproj/project.pbxproj

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matrix_dummy.cpp

@@ -6,8 +6,13 @@
 //
 
 #include "matrix.hpp"
+#include "matrix_helpers.hpp"
 
 namespace math { namespace matrix {
   template class matrix<int, 2, 2>;
   template class row_reference<int, 2>;
+  template matrix<double, 4, 4> identity();
+  template matrix<double, 4, 4> diagonal(vector::vector<double, 4> const &);
+  template matrix<double, 4, 4> translation(vector::vector<double, 3> const &);
+  template matrix<double, 4, 4> scalar(vector::vector<double, 3> const &);
 } }

matrix_helper_test.cpp

@@ -0,0 +1,33 @@
+//
+//  matrix_helper_test.cpp
+//  matrix
+//
+//  Created by Sam Jaffe on 6/3/18.
+//
+
+#include <gmock/gmock.h>
+
+#include "matrix_helpers.hpp"
+
+template <std::size_t N> using vec = math::vector::vector<double, N>;
+
+TEST(MatrixHelper, IdentityFunctionProducesOnes) {
+  auto iden = math::matrix::identity<double, 4>();
+  VECTOR_FOR_EACH_RANGE(i, 4) {
+    EXPECT_THAT(iden.at(i, i), 1.0);
+  }
+  MATRIX_FOR_EACH_RANGE(i, 4, j, 4) {
+    EXPECT_TRUE(i == j || iden.at(i, j) == 0);
+  }
+}
+
+TEST(MatrixHelper, DiagonalWillFillWithAllZeros) {
+  vec<4> const vector({1.5, 0.5, -1.0, 2.2});
+  auto diag = math::matrix::diagonal(vector);
+  VECTOR_FOR_EACH_RANGE(i, 4) {
+    EXPECT_THAT(diag.at(i, i), vector.at(i));
+  }
+  MATRIX_FOR_EACH_RANGE(i, 4, j, 4) {
+    EXPECT_TRUE(i == j || diag.at(i, j) == 0);
+  }
+}