fuzz: add custom function to fuzzer

Author: antonmedv

repl/repl.go

@@ -9,6 +9,7 @@ import (
 	"github.com/expr-lang/expr/test/fuzz"
 
 	"github.com/bettercap/readline"
+
 	"github.com/expr-lang/expr"
 	"github.com/expr-lang/expr/builtin"
 	"github.com/expr-lang/expr/debug"
@@ -29,6 +30,8 @@ func main() {
 	for name := range env {
 		keywords = append(keywords, name)
 	}
+	fn := fuzz.Func()
+	keywords = append(keywords, "fn")
 	home, err := os.UserHomeDir()
 	if err != nil {
 		panic(err)
@@ -81,7 +84,7 @@ func main() {
 			continue
 		}
 
-		program, err = expr.Compile(line, expr.Env(env))
+		program, err = expr.Compile(line, expr.Env(env), fn)
 		if err != nil {
 			fmt.Printf("compile error: %s\n", err)
 			continue

test/fuzz/fuzz_env.go

@@ -1,5 +1,11 @@
 package fuzz
 
+import (
+	"fmt"
+
+	"github.com/expr-lang/expr"
+)
+
 func NewEnv() map[string]any {
 	return map[string]any{
 		"ok":    true,
@@ -25,6 +31,12 @@ func NewEnv() map[string]any {
 	}
 }
 
+func Func() expr.Option {
+	return expr.Function("fn", func(params ...any) (any, error) {
+		return fmt.Sprintf("fn(%v)", params), nil
+	})
+}
+
 type Foo struct {
 	Bar string
 }

test/fuzz/fuzz_test.go

@@ -54,13 +54,14 @@ func FuzzExpr(f *testing.F) {
 	}
 
 	env := NewEnv()
+	fn := Func()
 
 	f.Fuzz(func(t *testing.T, code string) {
 		if len(code) > 1000 {
 			t.Skip("too long code")
 		}
 
-		program, err := expr.Compile(code, expr.Env(env))
+		program, err := expr.Compile(code, expr.Env(env), fn)
 		if err != nil {
 			t.Skipf("compile error: %s", err)
 		}