1 files changed, 12 insertions, 9 deletions
diff --git a/src/ts/utils/assert.ts b/src/ts/utils/assert.ts
index 2f52c6a3b..15d3031ff 100644
--- a/src/ts/utils/assert.ts
+++ b/src/ts/utils/assert.ts
@@ -1,30 +1,33 @@
 import * as _ from 'lodash';
 import * as BigNumber from 'bignumber.js';
-import Web3 = require('web3');
+import Web3 from 'web3';
 import {SchemaValidator} from './schema_validator';
 
 const HEX_REGEX = /^0x[0-9A-F]*$/i;
 
 export const assert = {
-    isBigNumber(variableName: string, value: BigNumber.BigNumber) {
+    isBigNumber(variableName: string, value: BigNumber.BigNumber): void {
         const isBigNumber = _.isObject(value) && value.isBigNumber;
         this.assert(isBigNumber, this.typeAssertionMessage(variableName, 'BigNumber', value));
     },
-    isString(variableName: string, value: string) {
+    isUndefined(value: any, variableName?: string): void {
+        this.assert(_.isUndefined(value), this.typeAssertionMessage(variableName, 'undefined', value));
+    },
+    isString(variableName: string, value: string): void {
         this.assert(_.isString(value), this.typeAssertionMessage(variableName, 'string', value));
     },
-    isHexString(variableName: string, value: string) {
+    isHexString(variableName: string, value: string): void {
         this.assert(_.isString(value) && HEX_REGEX.test(value),
             this.typeAssertionMessage(variableName, 'HexString', value));
     },
-    isETHAddressHex(variableName: string, value: string) {
+    isETHAddressHex(variableName: string, value: string): void {
         const web3 = new Web3();
         this.assert(web3.isAddress(value), this.typeAssertionMessage(variableName, 'ETHAddressHex', value));
     },
-    isNumber(variableName: string, value: number) {
+    isNumber(variableName: string, value: number): void {
         this.assert(_.isFinite(value), this.typeAssertionMessage(variableName, 'number', value));
     },
-    doesConformToSchema(variableName: string, value: object, schema: Schema) {
+    doesConformToSchema(variableName: string, value: object, schema: Schema): void {
         const schemaValidator = new SchemaValidator();
         const validationResult = schemaValidator.validate(value, schema);
         const hasValidationErrors = validationResult.errors.length > 0;
@@ -33,12 +36,12 @@ Encountered: ${JSON.stringify(value, null, '\t')}
 Validation errors: ${validationResult.errors.join(', ')}`;
         this.assert(!hasValidationErrors, msg);
     },
-    assert(condition: boolean, message: string) {
+    assert(condition: boolean, message: string): void {
         if (!condition) {
             throw new Error(message);
         }
     },
-    typeAssertionMessage(variableName: string, type: string, value: any) {
+    typeAssertionMessage(variableName: string, type: string, value: any): string {
         return `Expected ${variableName} to be of type ${type}, encountered: ${value}`;
     },
 };