DEV-1479 ensure snake elimination turn is set (#93)

* ensure snake elimination turn is set

- centralise elimination update logic to a single place to ensure consistency

* doc the method

* testing

board.go

@@ -57,6 +57,7 @@ func (prevState *BoardState) Clone() *BoardState {
 		nextState.Snakes[i].Health = prevState.Snakes[i].Health
 		nextState.Snakes[i].Body = append([]Point{}, prevState.Snakes[i].Body...)
 		nextState.Snakes[i].EliminatedCause = prevState.Snakes[i].EliminatedCause
+		nextState.Snakes[i].EliminatedOnTurn = prevState.Snakes[i].EliminatedOnTurn
 		nextState.Snakes[i].EliminatedBy = prevState.Snakes[i].EliminatedBy
 	}
 	return nextState
@@ -551,3 +552,13 @@ func getDistanceBetweenPoints(a, b Point) int {
 func isSquareBoard(b *BoardState) bool {
 	return b.Width == b.Height
 }
+
+// EliminateSnake updates a snake's state to reflect that it was eliminated.
+// - "cause" identifies what type of event caused the snake to be eliminated
+// - "by" identifies which snake (if any, use empty string "" if none) eliminated the snake.
+// - "turn" is the turn number that this snake was eliminated on.
+func EliminateSnake(s *Snake, cause, by string, turn int) {
+	s.EliminatedCause = cause
+	s.EliminatedBy = by
+	s.EliminatedOnTurn = turn
+}

board_test.go

@@ -881,3 +881,11 @@ func TestPlaceFoodRandomly(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, len(b.Food), 0)
 }
+
+func TestEliminateSnake(t *testing.T) {
+	s := &Snake{}
+	EliminateSnake(s, "test-cause", "", 2)
+	require.Equal(t, "test-cause", s.EliminatedCause)
+	require.Equal(t, "", s.EliminatedBy)
+	require.Equal(t, 2, s.EliminatedOnTurn)
+}

constrictor_test.go

@@ -15,6 +15,7 @@ func TestConstrictorRulesetInterface(t *testing.T) {
 var constrictorMoveAndCollideMAD = gameTestCase{
 	"Constrictor Case Move and Collide",
 	&BoardState{
+		Turn:   41,
 		Width:  10,
 		Height: 10,
 		Snakes: []Snake{
@@ -47,6 +48,7 @@ var constrictorMoveAndCollideMAD = gameTestCase{
 				Health:           100,
 				EliminatedCause:  EliminatedByCollision,
 				EliminatedBy:     "two",
+				EliminatedOnTurn: 42,
 			},
 			{
 				ID:               "two",
@@ -54,6 +56,7 @@ var constrictorMoveAndCollideMAD = gameTestCase{
 				Health:           100,
 				EliminatedCause:  EliminatedByCollision,
 				EliminatedBy:     "one",
+				EliminatedOnTurn: 42,
 			},
 		},
 		Food:    []Point{},

solo_test.go

@@ -116,3 +116,34 @@ func TestSoloCreateNextBoardState(t *testing.T) {
 		gc.requireValidNextState(t, NewRulesetBuilder().PipelineRuleset(GameTypeSolo, NewPipeline(soloRulesetStages...)))
 	}
 }
+
+// Test a snake running right into the wall is properly eliminated
+func TestSoloEliminationOutOfBounds(t *testing.T) {
+	r := SoloRuleset{}
+
+	// Using MaxRand is important because it ensures that the snakes are consistently placed in a way this test will work.
+	// Actually random placement could result in the assumptions made by this test being incorrect.
+	initialState, err := CreateDefaultBoardState(MaxRand, 2, 2, []string{"one"})
+	require.NoError(t, err)
+
+	_, next, err := r.Execute(
+		initialState,
+		r.Settings(),
+		[]SnakeMove{{ID: "one", Move: "right"}},
+	)
+	require.NoError(t, err)
+	require.NotNil(t, initialState)
+
+	ended, next, err := r.Execute(
+		next,
+		r.Settings(),
+		[]SnakeMove{{ID: "one", Move: "right"}},
+	)
+	require.NoError(t, err)
+	require.NotNil(t, initialState)
+
+	require.True(t, ended)
+	require.Equal(t, EliminatedByOutOfBounds, next.Snakes[0].EliminatedCause)
+	require.Equal(t, "", next.Snakes[0].EliminatedBy)
+	require.Equal(t, 1, next.Snakes[0].EliminatedOnTurn)
+}

standard.go

@@ -184,7 +184,7 @@ func DamageHazardsStandard(b *BoardState, settings Settings, moves []SnakeMove)
 					snake.Health = SnakeMaxHealth
 				}
 				if snakeIsOutOfHealth(snake) {
-					snake.EliminatedCause = EliminatedByOutOfHealth
+					EliminateSnake(snake, EliminatedByOutOfHealth, "", b.Turn+1)
 				}
 			}
 		}
@@ -221,12 +221,12 @@ func EliminateSnakesStandard(b *BoardState, settings Settings, moves []SnakeMove
 		}
 
 		if snakeIsOutOfHealth(snake) {
-			snake.EliminatedCause = EliminatedByOutOfHealth
+			EliminateSnake(snake, EliminatedByOutOfHealth, "", b.Turn+1)
 			continue
 		}
 
 		if snakeIsOutOfBounds(snake, b.Width, b.Height) {
-			snake.EliminatedCause = EliminatedByOutOfBounds
+			EliminateSnake(snake, EliminatedByOutOfBounds, "", b.Turn+1)
 			continue
 		}
 	}
@@ -306,8 +306,7 @@ func EliminateSnakesStandard(b *BoardState, settings Settings, moves []SnakeMove
 		for i := 0; i < len(b.Snakes); i++ {
 			snake := &b.Snakes[i]
 			if snake.ID == elimination.ID {
-				snake.EliminatedCause = elimination.Cause
+				EliminateSnake(snake, elimination.Cause, elimination.By, b.Turn+1)
-				snake.EliminatedBy = elimination.By
 				break
 			}
 		}

standard_test.go

@@ -164,6 +164,7 @@ var standardCaseMoveEatAndGrow = gameTestCase{
 var standardMoveAndCollideMAD = gameTestCase{
 	"Standard Case Move and Collide",
 	&BoardState{
+		Turn:   0,
 		Width:  10,
 		Height: 10,
 		Snakes: []Snake{
@@ -196,6 +197,7 @@ var standardMoveAndCollideMAD = gameTestCase{
 				Health:           98,
 				EliminatedCause:  EliminatedByCollision,
 				EliminatedBy:     "two",
+				EliminatedOnTurn: 1,
 			},
 			{
 				ID:               "two",
@@ -203,6 +205,7 @@ var standardMoveAndCollideMAD = gameTestCase{
 				Health:           98,
 				EliminatedCause:  EliminatedByCollision,
 				EliminatedBy:     "one",
+				EliminatedOnTurn: 1,
 			},
 		},
 		Food:    []Point{},
@@ -279,6 +282,7 @@ func TestEatingOnLastMove(t *testing.T) {
 						Body:             []Point{{3, 1}, {3, 2}, {3, 3}},
 						Health:           0,
 						EliminatedCause:  EliminatedByOutOfHealth,
+						EliminatedOnTurn: 1,
 					},
 				},
 				Food: []Point{{9, 9}},
@@ -315,6 +319,7 @@ func TestHeadToHeadOnFood(t *testing.T) {
 	}{
 		{
 			&BoardState{
+				Turn:   41,
 				Width:  10,
 				Height: 10,
 				Snakes: []Snake{
@@ -346,6 +351,7 @@ func TestHeadToHeadOnFood(t *testing.T) {
 						Health:           100,
 						EliminatedCause:  EliminatedByHeadToHeadCollision,
 						EliminatedBy:     "two",
+						EliminatedOnTurn: 42,
 					},
 					{
 						ID:               "two",
@@ -353,6 +359,7 @@ func TestHeadToHeadOnFood(t *testing.T) {
 						Health:           100,
 						EliminatedCause:  EliminatedByHeadToHeadCollision,
 						EliminatedBy:     "one",
+						EliminatedOnTurn: 42,
 					},
 				},
 				Food: []Point{{9, 9}},
@@ -360,6 +367,7 @@ func TestHeadToHeadOnFood(t *testing.T) {
 		},
 		{
 			&BoardState{
+				Turn:   41,
 				Width:  10,
 				Height: 10,
 				Snakes: []Snake{
@@ -391,6 +399,7 @@ func TestHeadToHeadOnFood(t *testing.T) {
 						Health:           100,
 						EliminatedCause:  EliminatedByHeadToHeadCollision,
 						EliminatedBy:     "two",
+						EliminatedOnTurn: 42,
 					},
 					{
 						ID:     "two",
@@ -1277,6 +1286,7 @@ func TestMaybeDamageHazards(t *testing.T) {
 		Food                      []Point
 		ExpectedEliminatedCauses  []string
 		ExpectedEliminatedByIDs   []string
+		ExpectedEliminatedOnTurns []int
 	}{
 		{},
 		{
@@ -1284,12 +1294,14 @@ func TestMaybeDamageHazards(t *testing.T) {
 			Hazards:                   []Point{},
 			ExpectedEliminatedCauses:  []string{NotEliminated},
 			ExpectedEliminatedByIDs:   []string{""},
+			ExpectedEliminatedOnTurns: []int{0},
 		},
 		{
 			Snakes:                    []Snake{{Body: []Point{{0, 0}}}},
 			Hazards:                   []Point{{0, 0}},
 			ExpectedEliminatedCauses:  []string{EliminatedByOutOfHealth},
 			ExpectedEliminatedByIDs:   []string{""},
+			ExpectedEliminatedOnTurns: []int{42},
 		},
 		{
 			Snakes:                    []Snake{{Body: []Point{{0, 0}}}},
@@ -1297,12 +1309,14 @@ func TestMaybeDamageHazards(t *testing.T) {
 			Food:                      []Point{{0, 0}},
 			ExpectedEliminatedCauses:  []string{NotEliminated},
 			ExpectedEliminatedByIDs:   []string{""},
+			ExpectedEliminatedOnTurns: []int{0},
 		},
 		{
 			Snakes:                    []Snake{{Body: []Point{{0, 0}, {1, 0}, {2, 0}}}},
 			Hazards:                   []Point{{1, 0}, {2, 0}},
 			ExpectedEliminatedCauses:  []string{NotEliminated},
 			ExpectedEliminatedByIDs:   []string{""},
+			ExpectedEliminatedOnTurns: []int{0},
 		},
 		{
 			Snakes: []Snake{
@@ -1312,6 +1326,7 @@ func TestMaybeDamageHazards(t *testing.T) {
 			Hazards:                   []Point{{1, 0}, {2, 0}, {3, 4}, {3, 5}, {3, 6}},
 			ExpectedEliminatedCauses:  []string{NotEliminated, NotEliminated},
 			ExpectedEliminatedByIDs:   []string{"", ""},
+			ExpectedEliminatedOnTurns: []int{0, 0},
 		},
 		{
 			Snakes: []Snake{
@@ -1321,17 +1336,20 @@ func TestMaybeDamageHazards(t *testing.T) {
 			Hazards:                   []Point{{3, 3}},
 			ExpectedEliminatedCauses:  []string{NotEliminated, EliminatedByOutOfHealth},
 			ExpectedEliminatedByIDs:   []string{"", ""},
+			ExpectedEliminatedOnTurns: []int{0, 42},
 		},
 	}
 
 	for _, test := range tests {
-		b := &BoardState{Snakes: test.Snakes, Hazards: test.Hazards, Food: test.Food}
+		b := &BoardState{Turn: 41, Snakes: test.Snakes, Hazards: test.Hazards, Food: test.Food}
 		r := StandardRuleset{HazardDamagePerTurn: 100}
 		_, err := DamageHazardsStandard(b, r.Settings(), mockSnakeMoves())
 		require.NoError(t, err)
 
 		for i, snake := range b.Snakes {
 			require.Equal(t, test.ExpectedEliminatedCauses[i], snake.EliminatedCause)
+			require.Equal(t, test.ExpectedEliminatedByIDs[i], snake.EliminatedBy)
+			require.Equal(t, test.ExpectedEliminatedOnTurns[i], snake.EliminatedOnTurn)
 		}
 
 	}