feat: wider fuzz tests, stronger options. (#9)

- Added all `Option`-s to the fuzz tests.
  - Minimum load is always <=20%.
- Tested all options, and force a panic on all invalid options.
  - Capacity must now be non-negative.
  - Minimum load should be <=20%, but just put it as a recommendation.

Reviewed-on: #9
Co-authored-by: M.V. Hutz <git@maximhutz.me>
Co-committed-by: M.V. Hutz <git@maximhutz.me>

cuckoo_fuzz_test.go

@@ -1,7 +1,10 @@
 package cuckoo_test
 
 import (
+	"fmt"
 	"maps"
+	"math"
+	"os"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -26,6 +29,8 @@ type fuzzStep struct {
 
 type fuzzScenario struct {
 	seedA, seedB           uint32
+	capacity, growthFactor uint8
+	load                   float64
 	steps                  []fuzzStep
 }
 
@@ -40,14 +45,33 @@ func FuzzInsertLookup(f *testing.F) {
 			return
 		}
 
-		if scenario.seedA == scenario.seedB {
+		seedA, seedB := scenario.seedA, scenario.seedB
-			return
+		growthFactor := max(2, int(scenario.growthFactor))
+		capacity := int(scenario.capacity)
+		minimumLoad := math.Abs(math.Mod(scenario.load, 1.0))
+
+		// If they are the same number, the hashes will clash, always causing an
+		// error.
+		if seedA == seedB {
+			t.Skip()
 		}
 
+		// If the load is too high, the hashs will not be able to allocate
+		// properly.
+		if minimumLoad > 0.20 {
+			t.Skip()
+		}
+
+		fmt.Fprintf(os.Stderr, "seedA=%d seedB=%d capacity=%d growthFactor=%d minimumLoad=%f\n",
+			seedA, seedB, capacity, growthFactor, minimumLoad)
+
 		actual := cuckoo.NewCustomTable[uint32, uint32](
-			offsetHash(scenario.seedA),
+			offsetHash(seedA),
-			offsetHash(scenario.seedB),
+			offsetHash(seedB),
 			func(a, b uint32) bool { return a == b },
+			cuckoo.Capacity(capacity),
+			cuckoo.GrowthFactor(growthFactor),
+			cuckoo.MinimumLoad(minimumLoad),
 		)
 
 		expected := map[uint32]uint32{}

settings.go

@@ -1,5 +1,7 @@
 package cuckoo
 
+import "fmt"
+
 // DefaultCapacity is the initial capacity of a [Table]. It is inspired from
 // Java's [HashMap] implementation, which also uses 16.
 //
@@ -27,19 +29,34 @@ type settings struct {
 type Option func(*settings)
 
 // Capacity modifies the starting capacity of each bucket of the [Table]. The
-// value must be greater than 0.
+// value must be non-negative.
 func Capacity(value int) Option {
+	if value < 0 {
+		panic(fmt.Sprintf("go-cuckoo: Capacity must be non-negative, got %d", value))
+	}
+
 	return func(s *settings) { s.bucketSize = uint64(value) }
 }
 
 // MinimumLoad modifies the [DefaultMinimumLoad] of the [Table]. The value must
 // be between 0.00 and 1.00.
+//
+// The higher the minimum load, the more likely that a [Table.Put] will not
+// succeed. Minimum loads above 20% are not tested.
 func MinimumLoad(value float64) Option {
+	if value < 0.00 || value > 1.00 {
+		panic(fmt.Sprintf("go-cuckoo: MinimumLoad must be between 0.00 and 1.00, got %f", value))
+	}
+
 	return func(s *settings) { s.minLoadFactor = value }
 }
 
 // GrowthFactor controls how much the capacity of the [Table] multiplies when
 // it must resize. The value must be greater than 1.
 func GrowthFactor(value int) Option {
+	if value < 2 {
+		panic(fmt.Sprintf("go-cuckoo: GrowthFactor must be greater than 1, got %d", value))
+	}
+
 	return func(s *settings) { s.growthFactor = uint64(value) }
 }