2 files changed, 69 insertions, 0 deletions
diff --git a/packages/dev-utils/src/callback_error_reporter.ts b/packages/dev-utils/src/callback_error_reporter.ts
new file mode 100644
index 000000000..c8e693673
--- /dev/null
+++ b/packages/dev-utils/src/callback_error_reporter.ts
@@ -0,0 +1,68 @@
+import * as chai from 'chai';
+import * as _ from 'lodash';
+
+import { DoneCallback } from '@0xproject/types';
+
+const expect = chai.expect;
+
+export const callbackErrorReporter = {
+    reportNoErrorCallbackErrors(done: DoneCallback, expectToBeCalledOnce = true) {
+        const callback = <T>(f?: (value: T) => void) => {
+            const wrapped = (value: T) => {
+                if (_.isUndefined(f)) {
+                    done();
+                    return;
+                }
+                try {
+                    f(value);
+                    if (expectToBeCalledOnce) {
+                        done();
+                    }
+                } catch (err) {
+                    done(err);
+                }
+            };
+            return wrapped;
+        };
+        return callback;
+    },
+    reportNodeCallbackErrors(done: DoneCallback, expectToBeCalledOnce = true) {
+        const callback = <T>(f?: (value: T) => void) => {
+            const wrapped = (error: Error | null, value: T | undefined) => {
+                if (!_.isNull(error)) {
+                    done(error);
+                } else {
+                    if (_.isUndefined(f)) {
+                        done();
+                        return;
+                    }
+                    try {
+                        f(value as T);
+                        if (expectToBeCalledOnce) {
+                            done();
+                        }
+                    } catch (err) {
+                        done(err);
+                    }
+                }
+            };
+            return wrapped;
+        };
+        return callback;
+    },
+    assertNodeCallbackError(done: DoneCallback, errMsg: string) {
+        const wrapped = <T>(error: Error | null, value: T | undefined) => {
+            if (_.isNull(error)) {
+                done(new Error('Expected callback to receive an error'));
+            } else {
+                try {
+                    expect(error.message).to.be.equal(errMsg);
+                    done();
+                } catch (err) {
+                    done(err);
+                }
+            }
+        };
+        return wrapped;
+    },
+};
diff --git a/packages/dev-utils/src/index.ts b/packages/dev-utils/src/index.ts
index 2ff2a2238..9124f3e28 100644
--- a/packages/dev-utils/src/index.ts
+++ b/packages/dev-utils/src/index.ts
@@ -3,3 +3,4 @@ export { web3Factory } from './web3_factory';
 export { constants as devConstants } from './constants';
 export { coverage } from './coverage';
 export { env, EnvVars } from './env';
+export { callbackErrorReporter } from './callback_error_reporter';