chore: test anonymous system

test/BUILD.bazel

@@ -57,3 +57,19 @@ cc_test(
         "@com_google_googletest//:gtest_main",
     ],
 )
+
+cc_test(
+    name = "anonymous_system",
+    srcs = ["anonymous_system.cc"],
+    copts = copts,
+    data = [
+        "anonymous_system.ecsact",
+    ],
+    deps = [
+        ":test_lib",
+        "//:ecsact_interpret",
+        "@bazel_sundry//bazel_sundry:runfiles",
+        "@com_google_googletest//:gtest",
+        "@com_google_googletest//:gtest_main",
+    ],
+)

test/anonymous_system.cc

@@ -0,0 +1,32 @@
+#include "gtest/gtest.h"
+#include "ecsact/interpret/eval.h"
+#include "ecsact/runtime/meta.hh"
+
+#include "test/test_lib.hh"
+
+TEST(EcsactInterpret, AllowAnonymousSystem) {
+	auto errs = ecsact_interpret_test_files({"anonymous_system.ecsact"});
+	ASSERT_EQ(errs.size(), 0) //
+		<< "Expected no errors. Instead got: " << errs[0].error_message << "\n";
+
+	auto package_ids = ecsact::meta::get_package_ids();
+	ASSERT_EQ(package_ids.size(), 1);
+
+	auto sys_ids = ecsact::meta::get_system_ids(package_ids[0]);
+	ASSERT_EQ(sys_ids.size(), 1);
+
+	auto sys_name = ecsact::meta::system_name(sys_ids[0]);
+	ASSERT_TRUE(sys_name.empty());
+
+	auto sys_caps = ecsact::meta::system_capabilities(sys_ids[0]);
+	ASSERT_EQ(sys_caps.size(), 1);
+
+	auto comp_ids = ecsact::meta::get_component_ids(package_ids[0]);
+	ASSERT_EQ(comp_ids.size(), 1);
+
+	ASSERT_EQ(sys_caps.begin()->second, ECSACT_SYS_CAP_REMOVES);
+	ASSERT_EQ(
+		sys_caps.begin()->first,
+		ecsact_id_cast<ecsact_component_like_id>(comp_ids[0])
+	);
+}

test/anonymous_system.ecsact

@@ -0,0 +1,7 @@
+package example.anonymous_sys;
+
+component MyComponent;
+
+// Trival anonymous system that always removes MyComponent
+system { removes MyComponent; }
+