#12 add unit tests for precedence func

internal/rule/factory.go

@@ -72,7 +72,7 @@ func reversePolishNotationSort(tokens []Token) []Token {
 		if isOperator(token) {
 			if v, ok := operatorStack.Peek(); ok {
 				vt := v.(Token)
-				if isGreaterOperatorOnStack(token, vt) {
+				if isTokenWithGreaterPrecedenceFromThePrecedenceSlice(token, vt) {
 					for !operatorStack.Empty() {
 						v, ok := operatorStack.Pop()
 						if !ok {
@@ -131,7 +131,7 @@ func isOperator(tkn Token) bool {
 	return false
 }
 
-func isGreaterOperatorOnStack(tkn Token, lastTknFromStack Token) bool {
+func isTokenWithGreaterPrecedenceFromThePrecedenceSlice(tkn Token, lastTknFromStack Token) bool {
 	var (
 		tknIdx              int
 		lastTknFromStackIdx int
@@ -148,5 +148,5 @@ func isGreaterOperatorOnStack(tkn Token, lastTknFromStack Token) bool {
 		}
 	}
 
-	return lastTknFromStackIdx > tknIdx
+	return lastTknFromStackIdx < tknIdx
 }

internal/rule/factory_test.go

@@ -38,3 +38,51 @@ func Test_isOperator(t *testing.T) {
 		})
 	}
 }
+
+func Test_isTokenWithGreaterPrecedenceFromThePrecedenceSlices(t *testing.T) {
+	type args struct {
+		tkn              Token
+		lastTknFromStack Token
+	}
+	tests := []struct {
+		name string
+		args args
+		want bool
+	}{
+		{
+			name: "token with greater precedence, true returned",
+			args: args{
+				tkn: Token{
+					Name:  tokenOr,
+					Value: tokenOr,
+				},
+				lastTknFromStack: Token{
+					Name:  tokenLParen,
+					Value: tokenLParen,
+				},
+			},
+			want: true,
+		},
+		{
+			name: "token with less precedence, false returned",
+			args: args{
+				tkn: Token{
+					Name:  tokenLParen,
+					Value: tokenLParen,
+				},
+				lastTknFromStack: Token{
+					Name:  tokenOr,
+					Value: tokenOr,
+				},
+			},
+			want: false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := isTokenWithGreaterPrecedenceFromThePrecedenceSlice(tt.args.tkn, tt.args.lastTknFromStack); got != tt.want {
+				t.Errorf("isTokenWithGreaterPrecedenceFromThePrecedenceSlice() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}