feat(capability): 转码能力包（vendor 纯 Go AMR-NB 解码器 + 黄金向量逐样本对照 + 8 哨兵 + 注册面）

internal/capability/transcode/registry_test.go

@@ -0,0 +1,80 @@
+package transcode
+
+import (
+	"errors"
+	"testing"
+)
+
+// TestRegistryRegisterAndLookup 断言注册 / 查找 / 发现三件事。
+func TestRegistryRegisterAndLookup(t *testing.T) {
+	reg := NewRegistry()
+	codec := newStubCodec()
+	if err := reg.Register(codec); err != nil {
+		t.Fatalf("register: %v", err)
+	}
+	got, ok := reg.Lookup(FormatAMR, FormatWAV)
+	if !ok || got != Codec(codec) {
+		t.Fatalf("lookup = (%v, %v), want the registered codec", got, ok)
+	}
+	if _, ok := reg.Lookup(FormatWAV, FormatAMR); ok {
+		t.Fatalf("reverse route must not exist")
+	}
+	if n := reg.Len(); n != 1 {
+		t.Fatalf("Len = %d, want 1", n)
+	}
+	if formats := reg.Formats(); len(formats) != 2 || formats[0] != FormatAMR || formats[1] != FormatWAV {
+		t.Fatalf("Formats = %v, want [amr wav]（去重且有序）", formats)
+	}
+}
+
+// TestRegistryRejectsBadCodecs 断言不合法注册项被拒（nil / 空格式 / 自我转换），
+// 且 repeated 注册返回 ErrDuplicate。
+func TestRegistryRejectsBadCodecs(t *testing.T) {
+	reg := NewRegistry()
+	cases := []struct {
+		name  string
+		codec Codec
+	}{
+		{"nil", nil},
+		{"empty from", &stubCodec{from: "", to: FormatWAV}},
+		{"empty to", &stubCodec{from: FormatAMR, to: ""}},
+		{"identity", &stubCodec{from: FormatWAV, to: FormatWAV}},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			if err := reg.Register(tc.codec); !errors.Is(err, ErrInvalidCodec) {
+				t.Fatalf("err = %v, want ErrInvalidCodec", err)
+			}
+		})
+	}
+	if err := reg.Register(newStubCodec()); err != nil {
+		t.Fatalf("register: %v", err)
+	}
+	if err := reg.Register(newStubCodec()); !errors.Is(err, ErrDuplicate) {
+		t.Fatalf("duplicate err = %v, want ErrDuplicate", err)
+	}
+	if n := reg.Len(); n != 1 {
+		t.Fatalf("Len = %d after a rejected duplicate, want 1", n)
+	}
+}
+
+// TestRegistryFormatsDedupe 断言多路共享格式时 Formats 去重。
+func TestRegistryFormatsDedupe(t *testing.T) {
+	reg := NewRegistry()
+	if err := reg.Register(&stubCodec{from: FormatAMR, to: FormatWAV}); err != nil {
+		t.Fatalf("register: %v", err)
+	}
+	if err := reg.Register(&stubCodec{from: FormatWAV, to: FormatAMRWB}); err != nil {
+		t.Fatalf("register: %v", err)
+	}
+	want := []Format{FormatAMR, FormatAMRWB, FormatWAV}
+	got := reg.Formats()
+	if len(got) != len(want) {
+		t.Fatalf("Formats = %v, want %v", got, want)
+	}
+	for i := range want {
+		if got[i] != want[i] {
+			t.Fatalf("Formats = %v, want %v（有序）", got, want)
+		}
+	}
+}