1 files changed, 12 insertions, 3 deletions
diff --git a/packages/dev-utils/src/callback_error_reporter.ts b/packages/dev-utils/src/callback_error_reporter.ts
index c8e693673..8432bb5d4 100644
--- a/packages/dev-utils/src/callback_error_reporter.ts
+++ b/packages/dev-utils/src/callback_error_reporter.ts
@@ -6,7 +6,10 @@ import { DoneCallback } from '@0xproject/types';
 const expect = chai.expect;
 
 export const callbackErrorReporter = {
-    reportNoErrorCallbackErrors(done: DoneCallback, expectToBeCalledOnce = true) {
+    reportNoErrorCallbackErrors(
+        done: DoneCallback,
+        expectToBeCalledOnce: boolean = true,
+    ): <T>(f?: ((value: T) => void) | undefined) => (value: T) => void {
         const callback = <T>(f?: (value: T) => void) => {
             const wrapped = (value: T) => {
                 if (_.isUndefined(f)) {
@@ -26,7 +29,10 @@ export const callbackErrorReporter = {
         };
         return callback;
     },
-    reportNodeCallbackErrors(done: DoneCallback, expectToBeCalledOnce = true) {
+    reportNodeCallbackErrors(
+        done: DoneCallback,
+        expectToBeCalledOnce: boolean = true,
+    ): <T>(f?: ((value: T) => void) | undefined) => (error: Error | null, value: T | undefined) => void {
         const callback = <T>(f?: (value: T) => void) => {
             const wrapped = (error: Error | null, value: T | undefined) => {
                 if (!_.isNull(error)) {
@@ -50,7 +56,10 @@ export const callbackErrorReporter = {
         };
         return callback;
     },
-    assertNodeCallbackError(done: DoneCallback, errMsg: string) {
+    assertNodeCallbackError(
+        done: DoneCallback,
+        errMsg: string,
+    ): <T>(error: Error | null, value: T | undefined) => void {
         const wrapped = <T>(error: Error | null, value: T | undefined) => {
             if (_.isNull(error)) {
                 done(new Error('Expected callback to receive an error'));