diff --git a/drawfence_test.go b/drawfence_test.go
index 113a316..85bddbf 100644
--- a/drawfence_test.go
+++ b/drawfence_test.go
@@ -57,10 +57,7 @@ func fenceRoots(t *testing.T, f *Generator) []fenceRoot {
 func TestPairsFindWhatAWholeReplayFinds(t *testing.T) {
 	corpus := fenceCorpus(t)
 	roots := fenceRoots(t, corpus)
-	shipped, err := New()
-	if err != nil {
-		t.Fatalf("New() = %v", err)
-	}
+	shipped := newShippedWhole(t)
 	_ = walkNodes(shipped.root.children, func(path string, n node) error {
 		if tm, ok := n.(*template); ok {
 			roots = append(roots, fenceRoot{path, tm})
diff --git a/shape_test.go b/shape_test.go
index 50d48f2..a912b67 100644
--- a/shape_test.go
+++ b/shape_test.go
@@ -12,11 +12,7 @@ const shapePin = "testdata/shipped_shape.txt"
 
 // REPIN=1 rewrites the pin.
 func TestShippedShapeIsPinned(t *testing.T) {
-	f, err := New(WithSeed(1))
-	if err != nil {
-		t.Fatal(err)
-	}
-	got := shippedShape(f)
+	got := shippedShape(newShippedWhole(t, WithSeed(1)))
 	if os.Getenv("REPIN") == "1" {
 		if err := os.WriteFile(shapePin, []byte(got), 0o644); err != nil {
 			t.Fatal(err)
diff --git a/shipped_test.go b/shipped_test.go
new file mode 100644
index 0000000..13145dc
--- /dev/null
+++ b/shipped_test.go
@@ -0,0 +1,209 @@
+package fejkdata
+
+import (
+	"bytes"
+	"fmt"
+	"go/format"
+	"io/fs"
+	"os"
+	"reflect"
+	"slices"
+	"sort"
+	"sync"
+	"testing"
+)
+
+const shippedIndexFile = "shippedindex.go"
+
+// newShippedWhole loads every shipped category in New, as a --data-path load does, so a test
+// reads the whole shipped tree.
+func newShippedWhole(t testing.TB, opts ...Option) *Generator {
+	t.Helper()
+	data, err := fs.Sub(shippedFS, "data")
+	if err != nil {
+		t.Fatal(err)
+	}
+	f, err := New(append([]Option{WithoutShippedData(), WithDataFS(data)}, opts...)...)
+	if err != nil {
+		t.Fatalf("New() = %v", err)
+	}
+	return f
+}
+
+// loadedCategories is the dot path of every category f has parsed and linked.
+func loadedCategories(f *Generator) []string {
+	var out []string
+	var walk func(prefix string, g *folder)
+	walk = func(prefix string, g *folder) {
+		for _, name := range sortedNames(g.children) {
+			if sub, isFolder := g.children[name].(*folder); isFolder {
+				walk(join(prefix, name), sub)
+				continue
+			}
+			out = append(out, join(prefix, name))
+		}
+	}
+	walk("", &f.root)
+	return out
+}
+
+// REPIN=1 rewrites the index.
+func TestShippedIndexIsCurrent(t *testing.T) {
+	got, err := shippedIndexSource(newShippedWhole(t))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if os.Getenv("REPIN") == "1" {
+		if err := os.WriteFile(shippedIndexFile, got, 0o644); err != nil {
+			t.Fatal(err)
+		}
+		return
+	}
+	want, err := os.ReadFile(shippedIndexFile)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(got) != string(want) {
+		t.Fatalf("%s is stale for data/; rewrite it with REPIN=1", shippedIndexFile)
+	}
+}
+
+func shippedIndexSource(whole *Generator) ([]byte, error) {
+	var b bytes.Buffer
+	b.WriteString("// Code generated by TestShippedIndexIsCurrent with REPIN=1. DO NOT EDIT.\n\npackage fejkdata\n\nvar shippedIndex = map[string]shippedCategory{\n")
+	for _, s := range categorySites(&whole.root) {
+		fmt.Fprintf(&b, "%q: {", s.path)
+		if t, isTable := s.n.(*table); isTable && t.parentIndex >= 0 {
+			fmt.Fprintf(&b, "parent: %q, ", t.header[t.parentIndex])
+		}
+		ps := paths(s.n)
+		sort.Strings(ps)
+		fmt.Fprintf(&b, "paths: %#v},\n", ps)
+	}
+	b.WriteString("}\n")
+	return format.Source(b.Bytes())
+}
+
+func TestNewLoadsNoShippedCategory(t *testing.T) {
+	f, err := New()
+	if err != nil {
+		t.Fatalf("New() = %v", err)
+	}
+	if got := loadedCategories(f); len(got) > 0 {
+		t.Fatalf("New() loaded %v", got)
+	}
+}
+
+func TestReachingACategoryLoadsWhatItReads(t *testing.T) {
+	for _, tc := range []struct {
+		reach        func(f *Generator) error
+		want, absent []string
+	}{
+		{
+			reach: func(f *Generator) error { _, err := f.Fake("sv_SE.person.first"); return err },
+			want:  []string{"sv_SE.first-name", "sv_SE.last-name", "sv_SE.person", "sv_SE.sex", "sv_SE.title"},
+		},
+		{
+			reach:  func(f *Generator) error { _, err := f.Fake("geo.SE.region"); return err },
+			want:   []string{"geo.SE.locality", "geo.SE.municipality", "geo.SE.postal-code", "geo.SE.region", "geo.SE.street"},
+			absent: []string{"geo.SE.address", "geo.US.region"},
+		},
+		{
+			reach:  func(f *Generator) error { _, err := f.FakeTemplate("{/misc.territory[SE].name}"); return err },
+			want:   []string{"misc.territory", "misc.timezone"},
+			absent: []string{"misc.tld"},
+		},
+		{
+			reach:  func(f *Generator) error { _, err := f.FakeRecord("misc.uuid"); return err },
+			want:   []string{"misc.uuid"},
+			absent: []string{"misc.objectid"},
+		},
+		{
+			reach: func(f *Generator) error {
+				var v struct {
+					Name string `fake:"sv_SE.first-name"`
+				}
+				return f.FakeStruct(&v)
+			},
+			want:   []string{"sv_SE.first-name"},
+			absent: []string{"sv_SE.person"},
+		},
+	} {
+		f, err := New()
+		if err != nil {
+			t.Fatalf("New() = %v", err)
+		}
+		if err := tc.reach(f); err != nil {
+			t.Fatal(err)
+		}
+		got := loadedCategories(f)
+		for _, w := range tc.want {
+			if !slices.Contains(got, w) {
+				t.Errorf("loaded %v, want %s among them", got, w)
+			}
+		}
+		for _, a := range tc.absent {
+			if slices.Contains(got, a) {
+				t.Errorf("loaded %v, want %s left unloaded", got, a)
+			}
+		}
+	}
+}
+
+func TestADataPathLoadsTheShippedSetWhole(t *testing.T) {
+	f, err := New(WithDataPath(writeData(t, map[string]string{"x": `"y"`})))
+	if err != nil {
+		t.Fatalf("New() = %v", err)
+	}
+	if got, want := loadedCategories(f), loadedCategories(newShippedWhole(t, WithDataPath(writeData(t, map[string]string{"x": `"y"`})))); !reflect.DeepEqual(got, want) {
+		t.Fatalf("loaded %v, want %v", got, want)
+	}
+}
+
+func TestOnDemandRendersAsTheWholeLoad(t *testing.T) {
+	whole := newShippedWhole(t)
+	paths := whole.List()
+	lazy, err := New()
+	if err != nil {
+		t.Fatalf("New() = %v", err)
+	}
+	if got := lazy.List(); !reflect.DeepEqual(got, paths) {
+		t.Fatalf("List() on demand = %v, want %v", got, paths)
+	}
+	a, err := New(WithSeed(7))
+	if err != nil {
+		t.Fatal(err)
+	}
+	b := newShippedWhole(t, WithSeed(7))
+	for _, p := range paths {
+		for range 3 {
+			got, gotErr := a.Fake(p)
+			want, wantErr := b.Fake(p)
+			if got != want || (gotErr == nil) != (wantErr == nil) {
+				t.Fatalf("Fake(%q) on demand = %q, %v; whole = %q, %v", p, got, gotErr, want, wantErr)
+			}
+		}
+	}
+}
+
+func TestListRunsBesideAnOnDemandLoad(t *testing.T) {
+	f, err := New()
+	if err != nil {
+		t.Fatalf("New() = %v", err)
+	}
+	var wg sync.WaitGroup
+	for _, p := range []string{"sv_SE.person", "geo.US.address", "misc.territory"} {
+		wg.Add(2)
+		go func() {
+			defer wg.Done()
+			if _, err := f.Fake(p); err != nil {
+				t.Error(err)
+			}
+		}()
+		go func() {
+			defer wg.Done()
+			f.List()
+		}()
+	}
+	wg.Wait()
+}