Implement context IsEmpty check

context.cc

@@ -56,6 +56,16 @@ void ContextFree(ContextPtr ctx) {
   delete ctx;
 }
 
+int ContextIsEmpty(ContextPtr ctx) {
+  // ContextFree deletes ContextPtr, so we have to handle the case
+  // when the context was already closed, gracefully, by go side
+  if (ctx == nullptr) {
+    return 1;
+  }
+
+  return ctx->ptr.IsEmpty();
+}
+
 m_value* tracked_value(m_ctx* ctx, m_value* val) {
   // (rogchap) we track values against a context so that when the context is
   // closed (either manually or GC'd by Go) we can also release all the

context.go

@@ -127,6 +127,10 @@ func (c *Context) Close() {
 	c.ptr = nil
 }
 
+func (c *Context) IsEmpty() bool {
+	return C.ContextIsEmpty(c.ptr) != 0
+}
+
 func (c *Context) register() {
 	ctxMutex.Lock()
 	r := ctxRegistry[c.ref]

context.h

@@ -49,6 +49,7 @@ extern ContextPtr NewContext(IsolatePtr iso_ptr,
 extern int ContextRetainedValueCount(ContextPtr ctx);
 extern ValuePtr ContextGlobal(ContextPtr ctx_ptr);
 extern void ContextFree(ContextPtr ctx);
+extern int ContextIsEmpty(ContextPtr ctx);
 extern RtnValue RunScript(ContextPtr ctx_ptr,
                           const char* source,
                           const char* origin);

context_test.go

@@ -152,6 +152,27 @@ func TestRegistryFromJSON(t *testing.T) {
 	}
 }
 
+func TestContextIsEmpty(t *testing.T) {
+	iso := v8.NewIsolate()
+	defer iso.Dispose()
+
+	t.Run("Closed", func(t *testing.T) {
+		ctx := v8.NewContext(iso)
+		ctx.Close()
+
+		if !ctx.IsEmpty() {
+			t.Error("expected context to be empty. ctx.IsEmpty() == false")
+		}
+	})
+
+	t.Run("Active", func(t *testing.T) {
+		ctx := v8.NewContext(iso)
+		if ctx.IsEmpty() {
+			t.Error("expected context to be active. ctx.IsEmpty() == true")
+		}
+	})
+}
+
 func BenchmarkContext(b *testing.B) {
 	b.ReportAllocs()
 	iso := v8.NewIsolate()