feature: make it possible to pass a vlient to the init function

* add a test
* make pickChainUrl method availabale to the consumer
* move some code around a bit to simplify adding a client

Author: sebs

Readme.md

@@ -24,6 +24,26 @@ balance.then(function(balanceData){
 
 * [Polymer3 based example](https://github.com/hiherto-elements/test-app)
 
+
+## use a own instance of axios
+
+```js
+const axios = require('axios');
+const {
+  init,
+  pickChainUrl
+} = require('..');
+
+
+const chain = pickChainUrl(null);
+const client = axios.create({
+  baseURL: chain,
+  timeout: 10000
+});
+
+var api = init('apikey', null, 10000, client);
+```
+
 ## For testnet and L2s usage
 
 Supported:
@@ -41,7 +61,6 @@ Latest
 var api = require('etherscan-api').init('YourApiKey','rinkeby'. '3000');
 ```
 
-
 ## Install
 
  ```bash

index.js

@@ -1,6 +1,9 @@
 'use strict';
 const init = require('./lib/init');
+const pickChainUrl = require('./lib/pick-chain-url');
+
 
 module.exports = {
-  init
+  init,
+  pickChainUrl
 };

lib/get-request.js

@@ -1,33 +1,13 @@
 
-const axios = require('axios');
 /**
  * @param {string} chain
+ * @param {number} timeout
+ * @param {object} client
  * @returns {string}
  */
-function pickChainUrl(chain) {
-  if (!chain || !OTHER_API_URL_MAP[chain]) {
-    return MAIN_API_URL;
-  }
-  
-  return OTHER_API_URL_MAP[chain];
-}
-
 
-const MAIN_API_URL = 'https://api.etherscan.io';
-const OTHER_API_URL_MAP = {
-  ropsten: 'https://api-ropsten.etherscan.io',
-  kovan: 'https://api-kovan.etherscan.io',
-  rinkeby: 'https://api-rinkeby.etherscan.io',
-  homestead: 'https://api.etherscan.io',
-  arbitrum: 'https://api.arbiscan.io',
-  arbitrum_rinkeby: 'https://api-testnet.arbiscan.io'
-};
+module.exports = function(chain, timeout, client) {
 
-module.exports = function(chain, timeout) {
-  var client = axios.create({
-    baseURL: pickChainUrl(chain),
-    timeout: timeout
-  });
 
   /**
    * @param query

lib/init.js

@@ -1,32 +1,42 @@
 "use strict";
+const axios = require('axios');
 const log = require('./log');
 const proxy = require('./proxy');
 const stats = require('./stats');
 const block = require('./block');
 const transaction = require('./transaction');
 const contract = require('./contract');
 const account = require('./account');
+const pickChainUrl = require('./pick-chain-url');
 /**
  * @module etherscan/api
  */
 
+
 /**
  * @param {string} apiKey - (optional) Your Etherscan APIkey
  * @param {string} chain - (optional) Other chain keys [ropsten, rinkeby, kovan]
  * @param {number} timeout - (optional) Timeout in milliseconds for requests, default 10000
+ * @param {object} client - optional axios client instance
  */
-module.exports = function(apiKey, chain, timeout) {
+module.exports = function(apiKey, chain, timeout, client = null) {
 
   if (!apiKey) {
     apiKey = 'YourApiKeyToken';
   }
 
-
   if (!timeout) {
     timeout = 10000;
   }
 
-  var getRequest = require('./get-request')(chain, timeout);
+  if (!client) {
+    client = axios.create({
+      baseURL: pickChainUrl(chain),
+      timeout: timeout
+    });  
+  } 
+  
+  var getRequest = require('./get-request')(chain, timeout, client);
 
   /** @lends module:etherscan/api */
   return {

lib/pick-chain-url.js

@@ -0,0 +1,24 @@
+const MAIN_API_URL = 'https://api.etherscan.io';
+const OTHER_API_URL_MAP = {
+  ropsten: 'https://api-ropsten.etherscan.io',
+  kovan: 'https://api-kovan.etherscan.io',
+  rinkeby: 'https://api-rinkeby.etherscan.io',
+  homestead: 'https://api.etherscan.io',
+  arbitrum: 'https://api.arbiscan.io',
+  arbitrum_rinkeby: 'https://api-testnet.arbiscan.io'
+};
+
+/**
+ * gets  the correct urls of the backend 
+ * @param {string} chain 
+ * @returns Url of backend
+ */
+function pickChainUrl(chain) {
+    if (!chain || !OTHER_API_URL_MAP[chain]) {
+      return MAIN_API_URL;
+    }
+    return OTHER_API_URL_MAP[chain];
+}
+
+
+  module.exports = pickChainUrl;

test/pass-client-test.js

@@ -0,0 +1,28 @@
+'use strict';
+const assert = require('chai').assert;
+const axios = require('axios');
+const {
+  init,
+  pickChainUrl
+} = require('..');
+
+
+describe('pass client', function() {
+
+  it('executes successfully', function(done){
+
+    const chain = pickChainUrl(null);
+    const client = axios.create({
+      baseURL: chain,
+      timeout: 10000
+    });  
+
+
+    var api = init(process.env.API_KEY, null, 10000, client);
+    var txlist = api.account.getminedblocks('0x9dd134d14d1e65f84b706d6f205cd5b1cd03a46b');
+    txlist.then(function(res){
+      assert.ok(res);
+      done();
+    });
+  });
+});