2 files changed, 30 insertions, 0 deletions
diff --git a/test/utils/constants.ts b/test/utils/constants.ts
index 9b150b5c1..2e9a84e64 100644
--- a/test/utils/constants.ts
+++ b/test/utils/constants.ts
@@ -2,5 +2,6 @@ export const constants = {
     NULL_ADDRESS: '0x0000000000000000000000000000000000000000',
     RPC_HOST: 'localhost',
     RPC_PORT: 8545,
+    RPC_NETWORK_ID: 50,
     KOVAN_RPC_URL: 'https://kovan.0xproject.com',
 };
diff --git a/test/web3_trapper_test.ts b/test/web3_trapper_test.ts
new file mode 100644
index 000000000..d417c9af5
--- /dev/null
+++ b/test/web3_trapper_test.ts
@@ -0,0 +1,29 @@
+import * as chai from 'chai';
+import {web3Factory} from './utils/web3_factory';
+import {ZeroEx} from '../src/';
+import {Web3Wrapper} from '../src/web3_wrapper';
+import {constants} from './utils/constants';
+
+chai.config.includeStack = true;
+const expect = chai.expect;
+
+describe.only('Web3Wrapper', () => {
+    const web3Provider = web3Factory.create().currentProvider;
+    describe('#getNetworkIdIfExistsAsync', () => {
+        it('caches network id requests', async () => {
+            const web3Wrapper = (new ZeroEx(web3Provider) as any)._web3Wrapper as Web3Wrapper;
+            expect((web3Wrapper as any).networkIdIfExists).to.be.undefined();
+            const networkId = await web3Wrapper.getNetworkIdIfExistsAsync();
+            expect((web3Wrapper as any).networkIdIfExists).to.be.equal(constants.RPC_NETWORK_ID);
+        });
+        it('invalidates network id cache on setProvider call', async () => {
+            const web3Wrapper = (new ZeroEx(web3Provider) as any)._web3Wrapper as Web3Wrapper;
+            expect((web3Wrapper as any).networkIdIfExists).to.be.undefined();
+            const networkId = await web3Wrapper.getNetworkIdIfExistsAsync();
+            expect((web3Wrapper as any).networkIdIfExists).to.be.equal(constants.RPC_NETWORK_ID);
+            const newProvider = web3Factory.create().currentProvider;
+            web3Wrapper.setProvider(newProvider);
+            expect((web3Wrapper as any).networkIdIfExists).to.be.undefined();
+        });
+    });
+});