[Impeller] added tests for matrices (#47754)

[C++, Objective-C, Java style guides]: https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style

Author: gaaclarke

ci/licenses_golden/excluded_files

@@ -148,6 +148,7 @@
 ../../../flutter/impeller/fixtures
 ../../../flutter/impeller/geometry/README.md
 ../../../flutter/impeller/geometry/geometry_unittests.cc
+../../../flutter/impeller/geometry/matrix_unittests.cc
 ../../../flutter/impeller/geometry/rect_unittests.cc
 ../../../flutter/impeller/golden_tests/README.md
 ../../../flutter/impeller/golden_tests_harvester/.dart_tool

impeller/geometry/BUILD.gn

@@ -61,6 +61,7 @@ impeller_component("geometry_unittests") {
   testonly = true
   sources = [
     "geometry_unittests.cc",
+    "matrix_unittests.cc",
     "rect_unittests.cc",
   ]
 

impeller/geometry/geometry_asserts.h

@@ -39,7 +39,8 @@ inline ::testing::AssertionResult MatrixNear(impeller::Matrix a,
                && NumberNear(a.m[15], b.m[15]);
 
   return equal ? ::testing::AssertionSuccess()
-               : ::testing::AssertionFailure() << "Matrixes are not equal.";
+               : ::testing::AssertionFailure()
+                     << "Matrixes are not equal " << a << " " << b;
 }
 
 inline ::testing::AssertionResult QuaternionNear(impeller::Quaternion a,

impeller/geometry/matrix_unittests.cc

@@ -0,0 +1,28 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "gtest/gtest.h"
+
+#include "flutter/impeller/geometry/matrix.h"
+
+#include "flutter/impeller/geometry/geometry_asserts.h"
+
+namespace impeller {
+namespace testing {
+
+TEST(MatrixTest, Multiply) {
+  Matrix x(0.0, 0.0, 0.0, 1.0,  //
+           1.0, 0.0, 0.0, 1.0,  //
+           0.0, 1.0, 0.0, 1.0,  //
+           1.0, 1.0, 0.0, 1.0);
+  Matrix translate = Matrix::MakeTranslation({10, 20, 0});
+  Matrix result = translate * x;
+  EXPECT_TRUE(MatrixNear(result, Matrix(10.0, 20.0, 0.0, 1.0,  //
+                                        11.0, 20.0, 0.0, 1.0,  //
+                                        10.0, 21.0, 0.0, 1.0,  //
+                                        11.0, 21.0, 0.0, 1.0)));
+}
+
+}  // namespace testing
+}  // namespace impeller