Add item registry domain foundation

internal/modules/dnd/codec/itemregistry/codec_test.go

@@ -0,0 +1,97 @@
+package itemregistry
+
+import (
+	"bytes"
+	"encoding/json"
+	"os"
+	"reflect"
+	"strings"
+	"testing"
+
+	"gitea.maximumdirect.net/eric/notarius/internal/core/source"
+	"gitea.maximumdirect.net/eric/notarius/internal/framework/contracts"
+	"gitea.maximumdirect.net/eric/notarius/internal/modules/dnd"
+	"gitea.maximumdirect.net/eric/notarius/internal/modules/dnd/items/identity"
+)
+
+func validRegistry() dnd.ItemRegistry {
+	return dnd.ItemRegistry{Items: []dnd.Item{{
+		ID:         identity.DeriveID("Silver Key"),
+		Name:       "Silver Key",
+		SourceRefs: []source.SourceRef{{SourceID: "session-alpha", StartUnitID: 1, EndUnitID: 2}},
+	}}}
+}
+
+func TestCodecMatchesMaintainedDurableFixture(t *testing.T) {
+	raw, err := os.ReadFile("testdata/dnd_item_registry.v1.json")
+	if err != nil {
+		t.Fatalf("read durable fixture: %v", err)
+	}
+	codec := New()
+	value, err := codec.Decode(raw)
+	if err != nil {
+		t.Fatalf("Decode() error = %v", err)
+	}
+	if want := validRegistry(); !reflect.DeepEqual(value, want) {
+		t.Fatalf("Decode() = %#v, want %#v", value, want)
+	}
+	encoded, err := codec.Encode(value)
+	if err != nil {
+		t.Fatalf("Encode() error = %v", err)
+	}
+	var compact bytes.Buffer
+	if err := json.Compact(&compact, raw); err != nil {
+		t.Fatal(err)
+	}
+	if !bytes.Equal(encoded, compact.Bytes()) {
+		t.Fatalf("Encode() = %s, want %s", encoded, compact.Bytes())
+	}
+}
+
+func TestCodecOwnsDurableSchemaAndExactType(t *testing.T) {
+	codec := New()
+	schema := codec.Schema()
+	if codec.Kind() != dnd.ItemRegistryKind || codec.MediaType() != MediaType || schema.ID != SchemaID || schema.Name != SchemaName || schema.Version != SchemaVersion || !json.Valid(schema.JSONSchema) {
+		t.Fatalf("codec contract = %#v / %#v", codec, schema)
+	}
+}
+
+func TestCodecCandidateEncodingMetadataAndStrictDecode(t *testing.T) {
+	codec := New()
+	candidate := dnd.ItemRegistry{Items: []dnd.Item{{Name: "Silver Key"}}}
+	if content, err := codec.EncodeCandidate(candidate); err != nil || string(content) != `{"items":[{"id":"","name":"Silver Key","source_refs":null}]}` {
+		t.Fatalf("EncodeCandidate() = %s, %v", content, err)
+	}
+	if _, err := codec.Encode(candidate); err == nil || !strings.Contains(err.Error(), "item ID pattern") {
+		t.Fatalf("Encode() error = %v, want durable validation", err)
+	}
+	metadata := codec.Metadata(validRegistry())
+	if metadata["item_count"] != 1 {
+		t.Fatalf("Metadata() = %#v", metadata)
+	}
+	for _, content := range []string{
+		`{"items":[],"unexpected":true}`,
+		`{"items":[{"id":"` + identity.DeriveID("Silver Key") + `","name":"Silver Key","source_refs":[{"source_id":"s","start_unit_id":1,"end_unit_id":1,"unexpected":true}]}]}`,
+		`{"items":[]} {}`,
+	} {
+		if _, err := codec.Decode([]byte(content)); err == nil {
+			t.Fatalf("Decode(%s) error = nil", content)
+		}
+	}
+}
+
+func TestCodecSchemaAndMetadataAreDefensive(t *testing.T) {
+	codec := New()
+	first := codec.Schema()
+	first.JSONSchema[0] = '['
+	if next := codec.Schema(); !json.Valid(next.JSONSchema) || next.JSONSchema[0] == '[' {
+		t.Fatal("Schema() returned shared bytes")
+	}
+	metadata := codec.Metadata(validRegistry())
+	metadata["other"] = true
+	if next := codec.Metadata(validRegistry()); len(next) != 1 || next["item_count"] != 1 {
+		t.Fatalf("Metadata() = %#v", next)
+	}
+}
+
+var _ contracts.ArtifactCodec[dnd.ItemRegistry] = (*Codec)(nil)