Handle NaN - fixes #13

sets.go

@@ -46,8 +46,12 @@ func (s Set[T]) Clone() Set[T] {
 }
 
 // Add items to the set.
+// Add and thus its callers will panic() if NaN is passed in.
 func (s Set[T]) Add(item ...T) {
 	for _, i := range item {
+		if i != i { //nolint:gocritic // on purpose to find NaN
+			panic("NaN is not allowed in sets")
+		}
 		s[i] = struct{}{}
 	}
 }

sets_test.go

@@ -5,6 +5,7 @@ package sets_test
 
 import (
 	"encoding/json"
+	"math"
 	"math/rand"
 	"testing"
 
@@ -182,6 +183,26 @@ func TestGenerate(t *testing.T) {
 	}, "should match triplets")
 }
 
+func TestNotNaNFloats(t *testing.T) {
+	// Normal floats:
+	setA := sets.New(math.Pi, math.Pi, math.Pi, math.E)
+	assert.Equal(t, 2, setA.Len())
+	assert.True(t, setA.Has(math.Pi))
+	assert.True(t, setA.Has(math.E))
+	// order
+	assert.Equal(t, []float64{math.E, math.Pi}, sets.Sort(setA))
+}
+
+func TestNaNFloats(t *testing.T) {
+	defer func() {
+		if r := recover(); r == nil {
+			t.Errorf("The code did not panic")
+		}
+	}()
+	_ = sets.New(math.NaN(), math.NaN(), math.NaN(), math.NaN())
+	t.Fatal("Shouldn't be reached, should have paniced")
+}
+
 func TestBadJson(t *testing.T) {
 	jsonStr := `[
 		"a,b",