From 5bd52c867cfd87f277f21ca87d908e0fafa7d6d8 Mon Sep 17 00:00:00 2001
From: dankelleher <dankelleher@yahoo.com>
Date: Thu, 4 Oct 2018 15:43:15 +0200
Subject: [PATCH] Support importing contract artifacts by url

---
 src/support/errors.js                   |  2 +-
 src/support/tx.js                       | 59 +++++++++++++++--------
 test/assets/contracts/mockContract.json |  3 ++
 test/tx.js                              | 64 ++++++++++++++++++++++++-
 4 files changed, 107 insertions(+), 21 deletions(-)
 create mode 100644 test/assets/contracts/mockContract.json

diff --git a/src/support/errors.js b/src/support/errors.js
index b02f0d6..b03b204 100644
--- a/src/support/errors.js
+++ b/src/support/errors.js
@@ -57,7 +57,7 @@ function mapError(error) {
 
 module.exports = {
   mapError,
-  CvcError: CvcError,
+  CvcError,
   InvalidNonceError,
   FailedTxChainError,
   NotDeployedError,
diff --git a/src/support/tx.js b/src/support/tx.js
index aaea15f..2cb1595 100644
--- a/src/support/tx.js
+++ b/src/support/tx.js
@@ -96,6 +96,27 @@ const fallbackToAutodetectDeployedContract = (contract, contractName) =>
     })
     .then(assertCodeAtAddress);
 
+/**
+ * Returns the contract artifact
+ * @param {string} contractName - The contact name.
+ * @returns {Promise<object>} The contract artifact.
+ */
+// eslint-disable-next-line consistent-return
+const getContractArtifact = contractName => {
+  if (config.contracts.url) {
+    // For frontend apps you can pass the url of the contracts
+    // eslint-disable-next-line no-undef
+    return fetch(`${config.contracts.url}/${contractName}.json`)
+      .then(res => res.json())
+      .then(data => Promise.resolve(data))
+      .catch(err => Promise.reject(err));
+  } else if (config.contracts.dir) {
+    // For backend servers you can pass the path of the contracts
+    // eslint-disable-next-line import/no-dynamic-require, global-require
+    return Promise.resolve(require(`./${path.join(config.contracts.dir, `${contractName}.json`)}`));
+  }
+};
+
 /**
  * Returns the contract instance by name.
  * @type {Function}
@@ -106,26 +127,27 @@ tx.contractInstance = _.memoize(contractName => {
       throw new Error(`Invalid contract name "${contractName}"`);
     }
     // Load contract artifact file.
-    // eslint-disable-next-line import/no-dynamic-require, global-require
-    const contractArtifact = require(`./${path.join(config.contracts.dir, `${contractName}.json`)}`);
-    // Create contract object.
-    const contract = truffleContract(contractArtifact);
-    contract.setProvider(tx.web3.currentProvider);
-
-    if (_.has(config, ['contracts', 'addresses', contractName])) {
-      const contractAddress = config.contracts.addresses[contractName];
-      try {
-        return contract.at(contractAddress).then(assertCodeAtAddress);
-      } catch (e) {
-        logger.debug(
-          `Contract '${contractName}' could not be found at configured '${contractAddress}'. Falling back to autodetect`
-        );
+    return getContractArtifact(contractName).then(contractArtifact => {
+      // Create contract object.
+      const contract = truffleContract(contractArtifact);
+      contract.setProvider(tx.web3.currentProvider);
+
+      if (_.has(config, ['contracts', 'addresses', contractName])) {
+        const contractAddress = config.contracts.addresses[contractName];
+        try {
+          return contract.at(contractAddress).then(assertCodeAtAddress);
+        } catch (e) {
+          logger.debug(
+            `Contract '${contractName}' could not be found at configured '${contractAddress}'. 
+            Falling back to autodetect`
+          );
+          return fallbackToAutodetectDeployedContract(contract, contractName);
+        }
+      } else {
+        logger.debug(`Address not configured for '${contractName}' contract. Using autodetect...`);
         return fallbackToAutodetectDeployedContract(contract, contractName);
       }
-    } else {
-      logger.debug(`Address not configured for '${contractName}' contract. Using autodetect...`);
-      return fallbackToAutodetectDeployedContract(contract, contractName);
-    }
+    });
   } catch (error) {
     logger.error(`Error loading contract ${contractName}`, error);
     return Promise.reject(new CvcError(`Error loading contract: ${contractName}`, error));
@@ -146,7 +168,6 @@ tx.contractInstance = _.memoize(contractName => {
  */
 tx.contractInstances = function(...contractNames) {
   const contractInstancePromises = contractNames.map(tx.contractInstance);
-
   return Promise.all(contractInstancePromises).then(contractInstances => _.zipObject(contractNames, contractInstances));
 };
 
diff --git a/test/assets/contracts/mockContract.json b/test/assets/contracts/mockContract.json
new file mode 100644
index 0000000..e9fec4e
--- /dev/null
+++ b/test/assets/contracts/mockContract.json
@@ -0,0 +1,3 @@
+{
+  "contractName": "CvcValidatorRegistry"
+}
\ No newline at end of file
diff --git a/test/tx.js b/test/tx.js
index 6e0420c..e0bcc17 100644
--- a/test/tx.js
+++ b/test/tx.js
@@ -3,13 +3,16 @@ require('longjohn');
 const chai = require('chai');
 const sandbox = require('sinon').createSandbox();
 const nonce = require('../src/support/nonce');
-const tx = require('../src/support/tx');
+const fetchMock = require('fetch-mock');
+const proxyquire = require('proxyquire');
 
 const { expect } = chai;
 chai.use(require('chai-as-promised'));
 
 describe('tx.js', () => {
   describe('when createTx throws', () => {
+    // eslint-disable-next-line global-require
+    const tx = require('../src/support/tx');
     let releaseNonceSpy;
     beforeEach('stub', () => {
       const getDataApplyStub = sandbox.stub().throws('Error', 'Invalid number of arguments to Solidity function');
@@ -46,6 +49,8 @@ describe('tx.js', () => {
   });
 
   describe('waitForMine', () => {
+    // eslint-disable-next-line global-require
+    const tx = require('../src/support/tx');
     before('Mining never resolves to a tx receipt', () => {
       sandbox.stub(tx, 'getTransactionReceipt').resolves(null);
     });
@@ -59,4 +64,61 @@ describe('tx.js', () => {
         /getTransactionReceiptMined timeout/
       )).timeout(4000);
   });
+
+  describe('When we pass contract.url to contractInstance', () => {
+    const tx = proxyquire('../src/support/tx', {
+      '../../config/index': () => ({
+        contracts: { url: './contracts' }
+      }),
+      'truffle-contract': () => ({
+        setProvider: () => {},
+        deployed: () => ({
+          catch: () => ({
+            then: () => Promise.resolve({ foo: 'bar' })
+          })
+        })
+      })
+    });
+    before('stub', () => {
+      tx.web3 = sandbox.stub().returns({});
+      fetchMock.mock('./contracts/CvcEscrow.json', { contractName: 'CvcEscrow' });
+    });
+
+    after(() => {
+      sandbox.restore();
+    });
+
+    it('should fetch the contract', async () => {
+      const result = await tx.contractInstance('CvcEscrow');
+      expect(result).to.deep.equal({ foo: 'bar' });
+    });
+  });
+
+  describe('When we pass contract.dir to contractInstance', () => {
+    const tx = proxyquire('../src/support/tx', {
+      '../../config/index': () => ({
+        contracts: { dir: '../../test/assets/contracts' }
+      }),
+      'truffle-contract': () => ({
+        setProvider: () => {},
+        deployed: () => ({
+          catch: () => ({
+            then: () => Promise.resolve({ foo: 'bar' })
+          })
+        })
+      })
+    });
+    before('stub', () => {
+      tx.web3 = sandbox.stub().returns({});
+    });
+
+    after(() => {
+      sandbox.restore();
+    });
+
+    it('should fetch the contract', async () => {
+      const result = await tx.contractInstance('mockContract');
+      expect(result).to.deep.equal({ foo: 'bar' });
+    });
+  });
 });