Difficulty creating test class on custom controller for table VF page that lists records from custom object

Question

i've spent nearly 2 days looking up how to write a test class and so I thought i'd now ask (works great in staging)

I have a custom controller that pulls records from a custom object, and then displays them as a table:

Apex class name: ouController

Custom object name: ou__c

---

public class ouController{

public List<ou__c> o_uy{get;set;}

 public ouController() {

    o_uy= [SELECT
         Affected_Receive_Country__c,
         Affected_Send_Country__c,
         Detailed_Description__c,
         End_Date__c,
         Incident_Description_for_CS__c,
         Incident_Status__c,
         Incident_Type__c,
         Service__c,
         Start_Date__c,
         Latest_Update__c,
         Customers_Notified__c,
         API_Enabled_Disabled__c,
         Action__c

             FROM ou__c
                 WHERE Incident_Status__c = 'Open'
                     ORDER BY Incident_Type__c DESC];
     }

  }

---

The VF page is this:

VF page name: o_u

---

 <apex:page Controller="ouController">

 <style>
 .headerclass{
 text-align:center;
 }
 </style>

<apex:pageBlock >           

    <apex:pageBlockTable value="{!o_uy}" var="ou__c" headerClass="headerclass" style="font-size:10.0pt;">>
        <apex:column value="{!ou__c.Start_Date__c}" style="{!IF(CONTAINS(ou__c.Incident_Type__c, 'Outage'), 'background-color: #FFC2C2;',IF(CONTAINS(ou__c.Incident_Type__c, 'Maintenance'), 'background-color: #9CDEFF;', 'background-color: #B0FF9C;'))}"/>
        <apex:column value="{!ou__c.End_Date__c}" style="{!IF(CONTAINS(ou__c.Incident_Type__c, 'Outage'), 'background-color: #FFC2C2;',IF(CONTAINS(ou__c.Incident_Type__c, 'Maintenance'), 'background-color: #9CDEFF;', 'background-color: #B0FF9C;'))}"/>
        <apex:column value="{!ou__c.Service__c}" style="{!IF(CONTAINS(ou__c.Incident_Type__c, 'Outage'), 'background-color: #FFC2C2;',IF(CONTAINS(ou__c.Incident_Type__c, 'Maintenance'), 'background-color: #9CDEFF;', 'background-color: #B0FF9C;'))}"/>
        <apex:column value="{!ou__c.Incident_Type__c}" style="{!IF(CONTAINS(ou__c.Incident_Type__c, 'Outage'), 'background-color: #FFC2C2;',IF(CONTAINS(ou__c.Incident_Type__c, 'Maintenance'), 'background-color: #9CDEFF;', 'background-color: #B0FF9C;'))}"/>
        <apex:column value="{!ou__c.Affected_Send_Country__c}" style="{!IF(CONTAINS(ou__c.Incident_Type__c, 'Outage'), 'background-color: #FFC2C2;',IF(CONTAINS(ou__c.Incident_Type__c, 'Maintenance'), 'background-color: #9CDEFF;', 'background-color: #B0FF9C;'))}"/>
        <apex:column value="{!ou__c.Affected_Receive_Country__c}" style="{!IF(CONTAINS(ou__c.Incident_Type__c, 'Outage'), 'background-color: #FFC2C2;',IF(CONTAINS(ou__c.Incident_Type__c, 'Maintenance'), 'background-color: #9CDEFF;', 'background-color: #B0FF9C;'))}"/>
        <apex:column value="{!ou__c.Incident_Description_for_CS__c}" style="{!IF(CONTAINS(ou__c.Incident_Type__c, 'Outage'), 'background-color: #FFC2C2;',IF(CONTAINS(ou__c.Incident_Type__c, 'Maintenance'), 'background-color: #9CDEFF;', 'background-color: #B0FF9C;'))}"/>  
        <apex:column value="{!ou__c.API_Enabled_Disabled__c}" style="{!IF(CONTAINS(ou__c.Incident_Type__c, 'Outage'), 'background-color: #FFC2C2;',IF(CONTAINS(ou__c.Incident_Type__c, 'Maintenance'), 'background-color: #9CDEFF;', 'background-color: #B0FF9C;'))}"/>            
        <apex:column value="{!ou__c.Customers_Notified__c}" style="{!IF(CONTAINS(ou__c.Incident_Type__c, 'Outage'), 'background-color: #FFC2C2;',IF(CONTAINS(ou__c.Incident_Type__c, 'Maintenance'), 'background-color: #9CDEFF;', 'background-color: #B0FF9C;'))}"/>            
        <apex:column value="{!ou__c.Latest_Update__c}" style="{!IF(CONTAINS(ou__c.Incident_Type__c, 'Outage'), 'background-color: #FFC2C2;',IF(CONTAINS(ou__c.Incident_Type__c, 'Maintenance'), 'background-color: #9CDEFF;', 'background-color: #B0FF9C;'))}"/>            
        <apex:column value="{!ou__c.Action__c}" style="{!IF(CONTAINS(ou__c.Incident_Type__c, 'Outage'), 'background-color: #FFC2C2;',IF(CONTAINS(ou__c.Incident_Type__c, 'Maintenance'), 'background-color: #9CDEFF;', 'background-color: #B0FF9C;'))}"/>            

    </apex:pageBlockTable>         
</apex:pageBlock>    

---

I'm really struggling here, i've gone through forums, Trailhead and the documentation. I understand that the purpose of the class is see what happens when a record from the custom object is passed through the controller

Conceptually, I believe it should be something like:

---

@isTest 
public class TestouController {
static testMethod void insertou() {

   ou__c testou__c = new ou__c();

   ou__c.Start_Date__c= DateTime.now();  //date/time field
   ou__c.End_Date__c= DateTime.now();  //date/time field
   ou__c.Service__c= 'Airtime';  //multi picklist field
   ou__c.Incident_Type__c= 'Maintenance';  //picklist field
   ou__c.Affected_Send_Country__c= 'Austria';  //picklist field
   ou__c.Affected_Receive_Country__c= 'Algeria';  //picklist field
   ou__c.Incident_Description_for_CS__c= 'test';  //text area 255 field
   ou__c.API_Enabled_Disabled__c= 'Enabled';  //picklist field
   ou__c.Customers_Notified__c= 'Email';  //multi picklist field
   ou__c.Latest_Update__c= 'test';  //Text(255) field
   ou__c.Action__c= 'test';  //text(50) field

   insert testou__c;
}
} 

---

However this is not working at all

Answer 1

That's a good start. You're inserting one record in your test class.

The problem is, you don't even call your controller in your test, so it can't be test. Your code is never executed.

So after having inserted record, you just have to call your controller.

Finally, you have to make some assertions to verify that your controller query returns your inserted record.

Here's the right test code:

@isTest 
public class TestouController {
static testMethod void insertou() {

   ou__c testOu = new ou__c();

   testOu.Start_Date__c= '11/09/2017';  //date/time field
   testOu.End_Date__c= '11/09/2017';  //date/time field
   testOu.Service__c= 'Airtime';  //multi picklist field
   testOu.Incident_Type__c= 'Maintenance';  //picklist field
   testOu.Affected_Send_Country__c= 'Austria';  //picklist field
   testOu.Affected_Receive_Country__c= 'Algeria';  //picklist field
   testOu.Incident_Description_for_CS__c= 'test';  //text area 255 field
   testOu.API_Enabled_Disabled__c= 'Enabled';  //picklist field
   testOu.Customers_Notified__c= 'Email';  //multi picklist field
   testOu.Latest_Update__c= 'test';  //Text(255) field
   testOu.Action__c= 'test';  //text(50) field
   testOu.Incident_Status__c = 'Open';

   insert testOu;

   ouController controller = new ouController(); //here you call your code

   System.assertEquals(testOu.Id, controller.o_uy[0].Id); // here you verify that your controller variable is instantiated with the right value, ie your previously inserted record
}
}