More test coverage

math/test/common_test.cxx

@@ -100,18 +100,35 @@ TEST_P(LineQuadTest, OriginLineIntersectsUnitSquare) {
   square const unit{{{0, 0}}, 1};
   line const ln{{{0, 0}}, GetParam()};
   EXPECT_TRUE(math::intersects(ln, unit));
+  EXPECT_TRUE(math::intersects(unit, ln));
+}
+
+TEST_P(LineQuadTest, CrossingLineIntersectsUnitSquare) {
+  square const unit{{{0, 0}}, 1};
+  line const ln{{{0.5, 0.5}}, GetParam()};
+  EXPECT_TRUE(math::intersects(ln, unit));
+  EXPECT_TRUE(math::intersects(unit, ln));
+}
+
+TEST_P(LineQuadTest, CrossingLineIntersectsSquare) {
+  square const unit{{{0, 0}}, 0.9};
+  line const ln{{{0.5, 0.5}}, GetParam()};
+  EXPECT_TRUE(math::intersects(ln, unit));
+  EXPECT_TRUE(math::intersects(unit, ln));
 }
 
 TEST_F(LineQuadTest, JustPointIntersection) {
   square const unit{{{0, 0}}, 1};
   line const ln{{{1, 1}}, {{2, 1}}};
   EXPECT_TRUE(math::intersects(ln, unit));
+  EXPECT_TRUE(math::intersects(unit, ln));
 }
 
 TEST_F(LineQuadTest, EntirelyEncasedIntersection) {
   square const unit{{{0, 0}}, 1};
   line const ln{{{0.5, 0.5}}, {{0.75, 0.75}}};
   EXPECT_TRUE(math::intersects(ln, unit));
+  EXPECT_TRUE(math::intersects(unit, ln));
 }
 
 TEST_F(LineQuadTest, OutsideByAnInch) {
@@ -119,6 +136,7 @@ TEST_F(LineQuadTest, OutsideByAnInch) {
   line const ln{{{1.001, 1}}, {{2, 1}}};
   math::intersects(ln, unit);
   EXPECT_FALSE(math::intersects(ln, unit));
+  EXPECT_FALSE(math::intersects(unit, ln));
 }
 
 INSTANTIATE_TEST_CASE_P(Intersects, LineQuadTest, ValuesIn(line_ends));