Fix Windows Wrappers and Extensions

internal/erf/erf_test.go

@@ -28,3 +28,31 @@ func TestArchiveRoundTrip(t *testing.T) {
 		t.Fatalf("unexpected first resource: %#v", decoded.Resources[0])
 	}
 }
+
+func TestExtensionMappingsKeep2DAAndTLKDistinct(t *testing.T) {
+	resourceType, ok := ResourceTypeForExtension("2da")
+	if !ok {
+		t.Fatal("expected 2da resource type")
+	}
+	if resourceType != 0x07E2 {
+		t.Fatalf("expected 2da type 0x07E2, got 0x%04X", resourceType)
+	}
+	extension, ok := ExtensionForResourceType(resourceType)
+	if !ok {
+		t.Fatal("expected canonical extension for 2da type")
+	}
+	if extension != "2da" {
+		t.Fatalf("expected 2da extension, got %q", extension)
+	}
+
+	tlkType, ok := ResourceTypeForExtension("tlk")
+	if !ok {
+		t.Fatal("expected tlk resource type")
+	}
+	if tlkType != 0x07E3 {
+		t.Fatalf("expected tlk type 0x07E3, got 0x%04X", tlkType)
+	}
+	if tlkType == resourceType {
+		t.Fatal("expected 2da and tlk resource types to stay distinct")
+	}
+}