diff --git a/dynamic/spec_test.go b/dynamic/spec_test.go
new file mode 100644
index 0000000..95e76d3
--- /dev/null
+++ b/dynamic/spec_test.go
@@ -0,0 +1,103 @@
+package dynamic
+
+import (
+	"errors"
+	"reflect"
+	"testing"
+)
+
+func TestInputCheck(t *testing.T) {
+	tcases := []struct {
+		Input map[string]reflect.Type
+		Fn    interface{}
+		Err   error
+	}{
+		// no input
+		{
+			Input: map[string]reflect.Type{},
+			Fn:    func() {},
+			Err:   nil,
+		},
+		// func can have any arguments if not specified
+		{
+			Input: map[string]reflect.Type{},
+			Fn:    func(int, string) {},
+			Err:   nil,
+		},
+		// missing input struct in func
+		{
+			Input: map[string]reflect.Type{
+				"Test1": reflect.TypeOf(int(0)),
+			},
+			Fn:  func() {},
+			Err: ErrMissingHandlerArgumentParam,
+		},
+		// input not a struct
+		{
+			Input: map[string]reflect.Type{
+				"Test1": reflect.TypeOf(int(0)),
+			},
+			Fn:  func(int) {},
+			Err: ErrMissingParamArgument,
+		},
+		// unexported param name
+		{
+			Input: map[string]reflect.Type{
+				"test1": reflect.TypeOf(int(0)),
+			},
+			Fn:  func(struct{}) {},
+			Err: ErrUnexportedName,
+		},
+		// input field missing
+		{
+			Input: map[string]reflect.Type{
+				"Test1": reflect.TypeOf(int(0)),
+			},
+			Fn:  func(struct{}) {},
+			Err: ErrMissingParamFromConfig,
+		},
+		// input field invalid type
+		{
+			Input: map[string]reflect.Type{
+				"Test1": reflect.TypeOf(int(0)),
+			},
+			Fn:  func(struct{ Test1 string }) {},
+			Err: ErrWrongParamTypeFromConfig,
+		},
+		// input field valid type
+		{
+			Input: map[string]reflect.Type{
+				"Test1": reflect.TypeOf(int(0)),
+			},
+			Fn:  func(struct{ Test1 int }) {},
+			Err: nil,
+		},
+	}
+
+	for i, tcase := range tcases {
+		t.Run("case."+string(i), func(t *testing.T) {
+			// mock spec
+			s := spec{
+				Input:  tcase.Input,
+				Output: nil,
+			}
+
+			err := s.checkInput(reflect.ValueOf(tcase.Fn))
+			if err == nil && tcase.Err != nil {
+				t.Errorf("expected an error: '%s'", tcase.Err.Error())
+				t.FailNow()
+			}
+			if err != nil && tcase.Err == nil {
+				t.Errorf("unexpected error: '%s'", err.Error())
+				t.FailNow()
+			}
+
+			if err != nil && tcase.Err != nil {
+				if !errors.Is(err, tcase.Err) {
+					t.Errorf("expected the error <%s> got <%s>", tcase.Err, err)
+					t.FailNow()
+				}
+			}
+		})
+	}
+}