feat: implement output formatting and display (HAN-383)

Add text and JSON formatters with real-time progress via traverser hooks,
summary statistics, and CLI integration for --show-* and --json flags.

Co-authored-by: multica-agent <github@multica.ai>

internal/output/formatter_test.go

@@ -0,0 +1,188 @@
+package output
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"net"
+	"strings"
+	"testing"
+
+	"github.com/hits/ExploreDNS/internal/dns"
+	"github.com/hits/ExploreDNS/internal/traverse"
+	miekgdns "github.com/miekg/dns"
+)
+
+func TestDefaultConfig(t *testing.T) {
+	cfg := DefaultConfig()
+	if !cfg.ShowProgress {
+		t.Fatal("expected ShowProgress default true")
+	}
+	if cfg.Format != FormatText {
+		t.Fatalf("Format = %v, want text", cfg.Format)
+	}
+}
+
+func TestNewFormatterSelectsImplementation(t *testing.T) {
+	text := NewFormatter(DefaultConfig(), &bytes.Buffer{})
+	if _, ok := text.(*textFormatter); !ok {
+		t.Fatalf("expected text formatter, got %T", text)
+	}
+
+	jsonCfg := DefaultConfig()
+	jsonCfg.Format = FormatJSON
+	jsonFmt := NewFormatter(jsonCfg, &bytes.Buffer{})
+	if _, ok := jsonFmt.(*jsonFormatter); !ok {
+		t.Fatalf("expected json formatter, got %T", jsonFmt)
+	}
+}
+
+func TestComputeSummaryAggregatesAnswers(t *testing.T) {
+	ref := traverse.NewReferral("example.com.", dns.TypeA, ".", 0, 1.0, nil)
+	resp := &traverse.Response{
+		Referral: ref,
+		Type:     traverse.RespAnswer,
+		Decoded: &dns.DecodedResponse{
+			Answers: []miekgdns.RR{
+				&miekgdns.A{
+					Hdr: miekgdns.RR_Header{Name: "example.com.", Rrtype: dns.TypeA, Class: miekgdns.ClassINET},
+					A:   net.ParseIP("93.184.216.34"),
+				},
+			},
+		},
+	}
+
+	stats := ComputeSummary([]traverse.TraversalResult{{Referral: ref, Response: resp}})
+	if len(stats.Answers) != 1 {
+		t.Fatalf("answers = %d, want 1", len(stats.Answers))
+	}
+	if stats.Answers[0].Prob != 1.0 {
+		t.Fatalf("prob = %v, want 1.0", stats.Answers[0].Prob)
+	}
+}
+
+func TestTextFormatterSummaryOutput(t *testing.T) {
+	ref := traverse.NewReferral("example.com.", dns.TypeA, ".", 0, 1.0, nil)
+	resp := &traverse.Response{
+		Referral: ref,
+		Type:     traverse.RespAnswer,
+		Decoded: &dns.DecodedResponse{
+			Answers: []miekgdns.RR{
+				&miekgdns.A{
+					Hdr: miekgdns.RR_Header{Name: "example.com.", Rrtype: dns.TypeA, Class: miekgdns.ClassINET},
+					A:   net.ParseIP("93.184.216.34"),
+				},
+			},
+		},
+	}
+
+	var buf bytes.Buffer
+	cfg := DefaultConfig()
+	cfg.Color = false
+	cfg.ShowServers = false
+	cfg.ShowResults = false
+	formatter := NewFormatter(cfg, &buf)
+
+	if err := formatter.WriteSummary([]traverse.TraversalResult{{Referral: ref, Response: resp}}); err != nil {
+		t.Fatalf("WriteSummary: %v", err)
+	}
+
+	out := buf.String()
+	if !strings.Contains(out, "Summary:") {
+		t.Fatalf("expected summary header, got %q", out)
+	}
+	if !strings.Contains(out, "100%") {
+		t.Fatalf("expected probability in summary, got %q", out)
+	}
+	if !strings.Contains(out, "93.184.216.34") {
+		t.Fatalf("expected answer IP in summary, got %q", out)
+	}
+}
+
+func TestJSONFormatterProducesValidOutput(t *testing.T) {
+	ref := traverse.NewReferral("example.com.", dns.TypeA, ".", 0, 1.0, nil)
+	resp := &traverse.Response{
+		Referral: ref,
+		Server:   net.ParseIP("198.41.0.4"),
+		Type:     traverse.RespAnswer,
+		Decoded: &dns.DecodedResponse{
+			Answers: []miekgdns.RR{
+				&miekgdns.A{
+					Hdr: miekgdns.RR_Header{Name: "example.com.", Rrtype: dns.TypeA, Class: miekgdns.ClassINET},
+					A:   net.ParseIP("93.184.216.34"),
+				},
+			},
+		},
+	}
+
+	var buf bytes.Buffer
+	cfg := DefaultConfig()
+	cfg.Format = FormatJSON
+	cfg.Domain = "example.com"
+	cfg.QueryType = "A"
+	cfg.ShowServers = false
+	cfg.ShowResults = true
+	cfg.ShowSummaryResults = true
+	formatter := NewFormatter(cfg, &buf)
+
+	if err := formatter.WriteProgress(traverse.TraversalEvent{
+		Stage:  traverse.EventStart,
+		Result: traverse.TraversalResult{Referral: ref},
+	}); err != nil {
+		t.Fatalf("WriteProgress: %v", err)
+	}
+	if err := formatter.WriteSummary([]traverse.TraversalResult{{Referral: ref, Response: resp}}); err != nil {
+		t.Fatalf("WriteSummary: %v", err)
+	}
+	if err := formatter.Flush(); err != nil {
+		t.Fatalf("Flush: %v", err)
+	}
+
+	var payload map[string]any
+	if err := json.Unmarshal(buf.Bytes(), &payload); err != nil {
+		t.Fatalf("invalid json: %v\n%s", err, buf.String())
+	}
+	if payload["domain"] != "example.com" {
+		t.Fatalf("domain = %v", payload["domain"])
+	}
+	if _, ok := payload["summary"]; !ok {
+		t.Fatalf("expected summary in json output")
+	}
+}
+
+func TestRunTraversalUsesHooks(t *testing.T) {
+	answerResp := func() *miekgdns.Msg {
+		m := new(miekgdns.Msg)
+		m.SetReply(new(miekgdns.Msg))
+		m.Answer = append(m.Answer, &miekgdns.A{
+			Hdr: miekgdns.RR_Header{Name: "example.com.", Rrtype: dns.TypeA, Class: miekgdns.ClassINET, Ttl: 300},
+			A:   net.ParseIP("93.184.216.34"),
+		})
+		return m
+	}()
+
+	tr := traverse.NewTraverser(&traverse.TraverserConfig{
+		MaxDepth:  5,
+		QueryType: dns.TypeA,
+		RootAddrs: []net.IP{net.ParseIP("198.41.0.4")},
+	})
+	tr.SetExchange(func(ctx context.Context, server string, msg *miekgdns.Msg, useTCP bool) (*miekgdns.Msg, error) {
+		return answerResp.Copy(), nil
+	})
+
+	var buf bytes.Buffer
+	cfg := DefaultConfig()
+	cfg.Color = false
+	cfg.ShowServers = false
+	cfg.ShowResults = false
+	cfg.ShowSummaryResults = true
+	formatter := NewFormatter(cfg, &buf)
+
+	_, err := RunTraversal(context.Background(), tr, cfg, formatter, "example.com")
+	if err != nil {
+		t.Fatalf("RunTraversal: %v", err)
+	}
+	if !strings.Contains(buf.String(), "Summary:") {
+		t.Fatalf("expected formatted summary output, got %q", buf.String())
+	}
+}