test: call exported function in imported function callback

test/wasmex_test.exs

@@ -427,4 +427,40 @@ defmodule WasmexTest do
       assert Wasmex.Memory.read_string(store, memory, string_ptr, length) == "Hello World!"
     end
   end
+
+  describe "call exported function in imported function callback" do
+    test "using instance in callback" do
+      wat = """
+      (module
+        (func $add_import (import "env" "add_import") (param i32 i32) (result i32))
+
+        (func $call_import (export "call_import") (param i32 i32) (result i32)
+          (call $add_import (local.get 0) (local.get 1))
+        )
+
+        (func $call_add (export "call_add") (param i32 i32) (result i32)
+          local.get 0
+          local.get 1
+          i32.add
+        )
+      )
+      """
+
+      imports = %{
+        env: %{add_import: {:fn, [:i32, :i32], [:i32], fn %{instance: instance, caller: caller}, a, b -> 
+          Wasmex.Instance.call_exported_function(caller, instance, "call_add", [a,b], :from) 
+          receive do {
+            :returned_function_call, {:ok, [result]}, :from} -> :ok 
+            result 
+          after 1000 ->  
+            raise "timeout on exported function call" end
+        end}}
+      }
+
+      {:ok, store} = Wasmex.Store.new()
+      {:ok, module} = Wasmex.Module.compile(store, wat)
+      pid = start_supervised!({Wasmex, %{store: store, module: module, imports: imports}})
+      assert Wasmex.call_function(pid, :call_import, [1, 2]) == {:ok, [3]}
+    end
+  end
 end