Add assert.isWeb3Provider

2 files changed, 5 insertions, 0 deletions

diff --git a/src/0x.ts b/src/0x.ts
index 9613df1be..a395d6dd7 100644
--- a/src/0x.ts
+++ b/src/0x.ts
@@ -163,6 +163,7 @@ export class ZeroEx {
      * @return  An instance of the 0x.js ZeroEx class.
      */
     constructor(provider: Web3Provider, config?: ZeroExConfig) {
+        assert.isWeb3Provider('provider', provider);
         if (_.isUndefined((provider as any).sendAsync)) {
             // Web3@1.0 provider doesn't support synchronous http requests,
             // so it only has `send` method, instead of `send and `sendAsync` in web3@0.x.x
diff --git a/src/utils/assert.ts b/src/utils/assert.ts
index a26b19311..eb084129c 100644
--- a/src/utils/assert.ts
+++ b/src/utils/assert.ts
@@ -61,6 +61,10 @@ export const assert = {
     isBoolean(variableName: string, value: boolean): void {
         this.assert(_.isBoolean(value), this.typeAssertionMessage(variableName, 'boolean', value));
     },
+    isWeb3Provider(variableName: string, value: Web3.Provider): void {
+        const isWeb3Provider = _.isFunction((value as any).send) || _.isFunction((value as any).sendAsync);
+        this.assert(isWeb3Provider, this.typeAssertionMessage(variableName, 'Web3.Provider', value));
+    },
     doesConformToSchema(variableName: string, value: any, schema: Schema): void {
         const schemaValidator = new SchemaValidator();
         const validationResult = schemaValidator.validate(value, schema);