Add CLI reports, snapshot format and duplicate detection

internal/duplicate/duplicate_test.go

@@ -0,0 +1,61 @@
+package duplicate
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/andydixon/mapsize/internal/scan"
+)
+
+func TestFind(t *testing.T) {
+	root := t.TempDir()
+	big := make([]byte, 200_000)
+	for i := range big {
+		big[i] = byte(i * 7)
+	}
+	w := func(name string, b []byte) {
+		if err := os.WriteFile(filepath.Join(root, name), b, 0o644); err != nil {
+			t.Fatal(err)
+		}
+	}
+	w("a.bin", big)
+	w("b.bin", big)
+	// Same size, same samples, different middle-of-nowhere byte: must not match.
+	c := append([]byte(nil), big...)
+	c[20_000] ^= 1
+	w("c.bin", c)
+	w("small1", []byte("hello"))
+	w("small2", []byte("hello"))
+	w("small3", []byte("world")) // same size, different content
+
+	s, err := scan.Start(context.Background(), root, scan.Options{Workers: 2})
+	if err != nil {
+		t.Fatal(err)
+	}
+	<-s.Done()
+	var f Finder
+	groups, err := f.Find(context.Background(), s.Tree, Options{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(groups) != 2 {
+		t.Fatalf("groups=%d want 2", len(groups))
+	}
+	names := func(g Group) (out []string) {
+		for _, id := range g.Files {
+			out = append(out, s.Tree.Node(id).Name)
+		}
+		return
+	}
+	if g := names(groups[0]); len(g) != 2 || groups[0].Size != 200_000 {
+		t.Fatalf("big group %v", g)
+	}
+	if g := names(groups[1]); len(g) != 2 {
+		t.Fatalf("small group %v", g)
+	}
+	if p := f.Progress(); p.Candidates != 6 || p.VerifiedGroups != 2 {
+		t.Fatalf("progress %+v", p)
+	}
+}