✅ Add test for RotateBlockedMissile (#5069)

Source/missiles.cpp

@@ -666,6 +666,13 @@ void SpawnLightning(Missile &missile, int dam)
 
 } // namespace
 
+#ifdef BUILD_TESTING
+void TestRotateBlockedMissile(Missile &missile)
+{
+	RotateBlockedMissile(missile);
+}
+#endif
+
 bool IsMissileBlockedByTile(Point tile)
 {
 	if (!InDungeonBounds(tile)) {

Source/missiles.h

@@ -431,4 +431,8 @@ void ProcessMissiles();
 void missiles_process_charge();
 void RedoMissileFlags();
 
+#ifdef BUILD_TESTING
+void TestRotateBlockedMissile(Missile &missile);
+#endif
+
 } // namespace devilution

test/missiles_test.cpp

@@ -1,9 +1,31 @@
 #include <gtest/gtest.h>
 
+#include "engine/random.hpp"
 #include "missiles.h"
 
 using namespace devilution;
 
+TEST(Missiles, RotateBlockedMissileArrow)
+{
+	Player &player = Players[0];
+	// missile can be a copy or a reference, there's no nullptr check and the functions that use it don't expect the instance to be part of a global structure so it doesn't really matter for this use.
+	Missile missile = *AddMissile({ 0, 0 }, { 0, 0 }, Direction::South, MIS_ARROW, TARGET_MONSTERS, player.getId(), 0, 0);
+	EXPECT_EQ(missile._miAnimFrame, 1);
+
+	SetRndSeed(0);
+	TestRotateBlockedMissile(missile);
+	EXPECT_EQ(missile._miAnimFrame, 16);
+
+	SetRndSeed(3210);
+	TestRotateBlockedMissile(missile);
+	EXPECT_EQ(missile._miAnimFrame, 1);
+
+	missile._miAnimFrame = 5;
+	SetRndSeed(1234);
+	TestRotateBlockedMissile(missile);
+	EXPECT_EQ(missile._miAnimFrame, 6);
+}
+
 TEST(Missiles, GetDirection8)
 {
 	EXPECT_EQ(Direction::South, GetDirection({ 0, 0 }, { 15, 15 }));