Fix function name and interface tests.

ruleset.go

@@ -35,5 +35,5 @@ type SnakeMove struct {
 type Ruleset interface {
 	CreateInitialBoardState(width int32, height int32, snakeIDs []string) (*BoardState, error)
 	CreateNextBoardState(prevState *BoardState, moves []SnakeMove) (*BoardState, error)
-	IsGameFinished(state *BoardState) (bool, error)
+	IsGameOver(state *BoardState) (bool, error)
 }

solo_test.go

@@ -6,6 +6,10 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
+func TestSoloRulesetInterface(t *testing.T) {
+	var _ Ruleset = (*SoloRuleset)(nil)
+}
+
 func TestSoloCreateNextBoardStateSanity(t *testing.T) {
 	boardState := &BoardState{}
 	r := SoloRuleset{}

standard_test.go

@@ -9,6 +9,10 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
+func TestStandardRulesetInterface(t *testing.T) {
+	var _ Ruleset = (*StandardRuleset)(nil)
+}
+
 func TestSanity(t *testing.T) {
 	r := StandardRuleset{}
 

team_test.go

@@ -6,6 +6,10 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
+func TestTeamRulesetInterface(t *testing.T) {
+	var _ Ruleset = (*TeamRuleset)(nil)
+}
+
 func TestCreateNextBoardStateSanity(t *testing.T) {
 	boardState := &BoardState{}
 	r := TeamRuleset{}