Thinking of enabling #Communities for your customer? Then be aware of the current #Gotcha that the default Apex Classes that are created when you enable your first Community do not ALL have code coverage >75%.

What this means:
You can enable Communities in Production, however as soon as you attempt to migrate anything from a sandbox into Production that triggers all tests to be run (doesn't have to be just code), your migration will fail as three of the classes only have 33%, 20% and 21%.

Let me repeat that, you might only be migrating a bunch of new custom fields and page layouts and the Change Set (or Eclipse/ANT) will fail.

I hit this problem this week in a go-live deployment so had to update Apex Classes to achieve average total code coverage >75% in order to proceed with our deployment.

The PM of Communities knows about the problem and advises he is looking at a fix, but in the meantime here are the four Apex Classes that need to be updated.

CommunitiesLandingControllerTest.cls

Just a one liner for this test class

/**
 * An apex page controller that takes the user to the right start page based on credentials or lack thereof
 */
@IsTest public with sharing class CommunitiesLandingControllerTest {
  @IsTest(SeeAllData=true) public static void testCommunitiesLandingController() {
    // Instantiate a new controller with all parameters in the page
    CommunitiesLandingController controller = new CommunitiesLandingController();

    // 25-Jun-2013 Manu Erwin - Fixing insufficient code coverage for default Communities Apex Tests
    PageReference pageRef = controller.forwardToStartPage();
  }
}

CommunitiesLoginControllerTest.cls

Just a one liner for this test class

/**
 * An apex page controller that exposes the site login functionality
 */
@IsTest global with sharing class CommunitiesLoginControllerTest {
  @IsTest(SeeAllData=true) 
  global static void testCommunitiesLoginController () {
    CommunitiesLoginController controller = new CommunitiesLoginController ();

    // 25-Jun-2013 Manu Erwin - Fixing insufficient code coverage for default Communities Apex Tests
    PageReference pageRef = controller.forwardToAuthPage();
  }  
}

CommunitiesSelfRegControllerTest.cls

A few controller variables to set prior to calling the controller method for the original test method, followed by a couple of additional test methods for further coverage.

/**
 * An apex page controller that supports self registration of users in communities that allow self registration
 */
@IsTest public with sharing class CommunitiesSelfRegControllerTest {
  @IsTest(SeeAllData=true) 
  public static void testCommunitiesSelfRegController() {
    CommunitiesSelfRegController controller = new CommunitiesSelfRegController();

    // 25-Jun-2013 Manu Erwin - Fixing insufficient code coverage for default Communities Apex Tests
    controller.firstName = 'Bob';
    controller.lastName = 'Jones';
    controller.email = 'bob@jones.com';
    controller.password = '8yhMsHDN&ituQgO$WO';
    controller.confirmPassword = '8yhMsHDN&ituQgO$WO';
    controller.communityNickname = 'bob-jones-testing';

    PageReference pageRef = controller.registerUser();
  }
  // 25-Jun-2013 Manu Erwin - Fixing insufficient code coverage for default Communities Apex Tests
  @IsTest(SeeAllData=true) 
  public static void testInvalidPassword() {
    CommunitiesSelfRegController controller = new CommunitiesSelfRegController();
    controller.firstName = 'Bob';
    controller.lastName = 'Jones';
    controller.email = 'bob@jones.com';
    controller.password = '8yhMsHDN&ituQgO$WO';
    controller.confirmPassword = 'not the same';
    controller.communityNickname = 'bob-jones-testing';

    PageReference pageRef = controller.registerUser();
    System.assert(pageRef == null, 'The returned page reference should be null');
  }
  // 25-Jun-2013 Manu Erwin - Fixing insufficient code coverage for default Communities Apex Tests
  @IsTest(SeeAllData=true) 
  public static void testNullPassword() {
    CommunitiesSelfRegController controller = new CommunitiesSelfRegController();
    controller.firstName = 'Bob';
    controller.lastName = 'Jones';
    controller.email = 'bob@jones.com';
    controller.communityNickname = 'bob-jones-testing';

    PageReference pageRef = controller.registerUser();
    System.assert(pageRef == null, 'The returned page reference should be null');
  }
}

CommunitiesSelfRegController.cls

A few additions to this class to set the Profile and Account Ids for portal user creation. Update the ProfileId value based on the "portal" license(s) (e.g., Customer Portal, Customer Community, etc) and set the AccountId to that of the Account you wish to use for self-registration. Note: this needs to be set even if you're not using self-registration so the class can be tested.

Plus some debug statements so I could see what was happening and needed to be tested.

/**
 * An apex page controller that supports self registration of users in communities that allow self registration
 */
public with sharing class CommunitiesSelfRegController {

  public String firstName {get; set;}
  public String lastName {get; set;}
  public String email {get; set;}
  public String password {get; set {password = value == null ? value : value.trim(); } }
  public String confirmPassword {get; set { confirmPassword = value == null ? value : value.trim(); } }
  public String communityNickname {get; set { communityNickname = value == null ? value : value.trim(); } }
  
  public CommunitiesSelfRegController() {}
  
  private boolean isValidPassword() {
    return password == confirmPassword;
  }

  public PageReference registerUser() {
  
    // it's okay if password is null - we'll send the user a random password in that case
    if (!isValidPassword()) {
      System.debug(System.LoggingLevel.DEBUG, '## DEBUG: Password is invalid - returning null');
      ApexPages.Message msg = new ApexPages.Message(ApexPages.Severity.ERROR, Label.site.passwords_dont_match);
      ApexPages.addMessage(msg);
      return null;
    }  

    // 25-Jun-2013 Manu Erwin - Fixing insufficient code coverage for default Communities Apex Tests
    //String profileId = ''; // To be filled in by customer.
    //String roleEnum = ''; // To be filled in by customer.
    //String accountId = ''; // To be filled in by customer.

    // Set this to your main Communities Profile API Name
    String profileApiName = 'PowerCustomerSuccess';
    String profileId = [SELECT Id FROM Profile WHERE UserType = :profileApiName LIMIT 1].Id;
    List<Account> accounts = [SELECT Id FROM Account LIMIT 1];
    System.assert(!accounts.isEmpty(), 'There must be at least one account in this environment!');
    String accountId = accounts[0].Id;
    
    String userName = email;

    User u = new User();
    u.Username = userName;
    u.Email = email;
    u.FirstName = firstName;
    u.LastName = lastName;
    u.CommunityNickname = communityNickname;
    u.ProfileId = profileId;
    
    String userId = Site.createPortalUser(u, accountId, password);
   
    if (userId != null) { 
      if (password != null && password.length() > 1) {
        System.debug(System.LoggingLevel.DEBUG, '## DEBUG: User creation successful and password ok - returning site.login');
        return Site.login(userName, password, null);
      }
      else {
        System.debug(System.LoggingLevel.DEBUG, '## DEBUG: User creation successful but password not ok - redirecting to self reg confirmation');
        PageReference page = System.Page.CommunitiesSelfRegConfirm;
        page.setRedirect(true);
        return page;
      }
    }
    System.debug(System.LoggingLevel.DEBUG, '## DEBUG: User creation not successful - returning null');
    return null;
  }
}