add sponge mutator

pkg/mutators/simple/simpleSponge.go

@@ -0,0 +1,21 @@
+package mutators
+
+import (
+	"bytes"
+	"io"
+
+	"github.com/batmac/ccat/pkg/log"
+)
+
+func init() {
+	simpleRegister("sponge", sponge, withDescription("soak all input before outputting it."))
+}
+
+func sponge(w io.WriteCloser, r io.ReadCloser) (int64, error) {
+	d, err := io.ReadAll(r) // NOT streamable (that the point :p)
+	if err != nil {
+		return 0, err
+	}
+	log.Debugf("soaked %d bytes\n", len(d))
+	return io.Copy(w, bytes.NewReader(d))
+}

pkg/mutators/simple/simpleSponge_test.go

@@ -0,0 +1,28 @@
+package mutators_test
+
+import (
+	"testing"
+
+	"github.com/batmac/ccat/pkg/mutators"
+)
+
+func Test_sponge(t *testing.T) {
+	tests := []struct {
+		name, decoded, encoded string
+	}{
+		{"empty", "", ""},
+		{"simple", "{}", "{}"},
+		{"abc", "abc", "abc"},
+		{"nl", "\n", "\n"},
+		{"3x nl", "\n\n\n", "\n\n\n"},
+	}
+
+	f := "sponge"
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := mutators.Run(f, tt.decoded); got != tt.encoded {
+				t.Errorf("%s = %v, want %v", f, got, tt.encoded)
+			}
+		})
+	}
+}