fix: allow lower bcrypt values and add tests

.schema/config.schema.json

@@ -787,7 +787,7 @@
                   "type": "integer",
                   "description": "Sets the BCrypt cost. The higher the value, the more CPU time is being used to generate hashes.",
                   "default": 10,
-                  "minimum": 8,
+                  "minimum": 4,
                   "maximum": 31
                 }
               }

x/hasher_test.go

@@ -0,0 +1,37 @@
+package x
+
+import (
+	"context"
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+type hasherConfig struct {
+	cost int
+}
+
+func (c hasherConfig) BCryptCost() int {
+	return c.cost
+}
+
+func TestHasher(t *testing.T) {
+	for _, cost := range []int{1, 8, 10, 16} {
+		result, err := NewBCrypt(&hasherConfig{cost: cost}).Hash(context.Background(), []byte("foobar"))
+		require.NoError(t, err)
+		require.NotEmpty(t, result)
+	}
+}
+
+func BenchmarkHasher(b *testing.B) {
+	for cost := 1; cost <= 16; cost++ {
+		b.Run(fmt.Sprintf("cost=%d", cost), func(b *testing.B) {
+			for n := 0; n < b.N; n++ {
+				result, err := NewBCrypt(&hasherConfig{cost: cost}).Hash(context.Background(), []byte("foobar"))
+				require.NoError(b, err)
+				require.NotEmpty(b, result)
+			}
+		})
+	}
+}