Add tests from vibe-d:core.

tests/vibe.core.core.refcount.d

@@ -0,0 +1,51 @@
+/+ dub.sdl:
+	name "tests"
+	description "Invalid ref count after runTask"
+	dependency "vibe-core" path="../"
++/
+module test;
+import vibe.core.core;
+import std.stdio;
+
+struct RC {
+	int* rc;
+	this(int* rc) { this.rc = rc; }
+	this(this) {
+		if (rc) {
+			(*rc)++;
+			writefln("addref %s", *rc);
+		}
+	}
+	~this() {
+		if (rc) {
+			(*rc)--;
+			writefln("release %s", *rc);
+		}
+	}
+}
+
+void main()
+{
+	int rc = 1;
+	bool done = false;
+
+	{
+		auto s = RC(&rc);
+		assert(rc == 1);
+		runTask((RC st) {
+			assert(rc == 2);
+			st = RC.init;
+			assert(rc == 1);
+			exitEventLoop();
+			done = true;
+		}, s);
+		assert(rc == 2);
+	}
+
+	assert(rc == 1);
+
+	runEventLoop();
+
+	assert(rc == 0);
+	assert(done);
+}