add tests for Authentication.sol, helper contract for error testing

contracts/Authentication.sol

@@ -9,8 +9,6 @@ contract Authentication is Killable {
 
   mapping (address => User) private users;
 
-  uint private id; // Stores user id temporarily
-
   modifier onlyExistingUser {
     // Check if user exists or terminate
 

test/TestAuthentication.sol

@@ -3,6 +3,7 @@ pragma solidity ^0.4.2;
 import "truffle/Assert.sol";
 import "truffle/DeployedAddresses.sol";
 import "../contracts/Authentication.sol";
+import "./helpers/ErrorProxy.sol";
 
 contract TestAuthentication {
 
@@ -13,7 +14,59 @@ contract TestAuthentication {
 
     bytes32 expected = 'testuser';
 
-    Assert.equal(authentication.login(), expected, "It should sign up and log in a user.");
+    Assert.equal(authentication.login(), expected, "It signs up and logs in a user.");
+  }
+
+  function testUserCanUpdateName() {
+    Authentication authentication = Authentication(DeployedAddresses.Authentication());
+
+    bytes32 expected = 'new_name';
+
+    Assert.equal(authentication.update('new_name'), expected, "It updates a user.");
+  }
+
+  function testLoginFailure() {
+    Authentication authentication = new Authentication();
+    ErrorProxy errorProxy = new ErrorProxy(address(authentication));
+
+    Authentication(address(errorProxy)).login();
+
+    bool r = errorProxy.execute.gas(200000)();
+
+    Assert.isFalse(r, "Only existings users can log in.");
+  }
+
+  function testSignUpFailure() {
+    Authentication authentication = new Authentication();
+    ErrorProxy errorProxy = new ErrorProxy(address(authentication));
+
+    Authentication(address(errorProxy)).signup('');
+
+    bool r = errorProxy.execute.gas(200000)();
+
+    Assert.isFalse(r, "Cannot sign up with invalid name.");
+  }
+
+  function testUpdateWithInvalidName() {
+    Authentication authentication = new Authentication();
+    ErrorProxy errorProxy = new ErrorProxy(address(authentication));
+
+    Authentication(address(errorProxy)).update('');
+
+    bool r = errorProxy.execute.gas(200000)();
+
+    Assert.isFalse(r, "Cannot update user with invalid name.");
+  }
+
+  function testUpdateWithInvalidUser() {
+    Authentication authentication = new Authentication();
+    ErrorProxy errorProxy = new ErrorProxy(address(authentication));
+
+    Authentication(address(errorProxy)).update('new_name');
+
+    bool r = errorProxy.execute.gas(200000)();
+
+    Assert.isFalse(r, "Cannot update non-existent user.");
   }
 
 }

test/authentication.js

@@ -2,7 +2,7 @@ var Authentication = artifacts.require("./Authentication.sol");
 
 contract('Authentication', function(accounts) {
 
-  it("...should sign up and log in a user.", function() {
+  it("...signs up and logs in a user.", function() {
     return Authentication.deployed().then(function(instance) {
       authenticationInstance = instance;
 

test/helpers/ErrorProxy.sol

@@ -0,0 +1,20 @@
+// Proxy contract for testing errors
+// http://truffleframework.com/tutorials/testing-for-throws-in-solidity-tests
+
+contract ErrorProxy {
+  address public target;
+  bytes data;
+
+  function ErrorProxy(address _target) {
+    target = _target;
+  }
+
+  //prime the data using the fallback function.
+  function() {
+    data = msg.data;
+  }
+
+  function execute() returns (bool) {
+    return target.call(data);
+  }
+}