public with sharing class MTX_MatrixDetailViewController {
 
    //sort activities
    actList = LightningActivityAccessor.sort(actList,'date','DESC');
    activities = JSON.serialize(actList);
    
  }
  
  

public with sharing class MTX_MatrixDetailViewController {
  public transient String activities {get;set;}
  public MTX_MatrixDetailViewController(){
    
    String candidateId = ApexPages.currentPage().getParameters().get('id');
     Map<String, String> filters = new Map<String, String>();
    
    List<LightningActivity> actList = LightningActivityAccessor.getLightningActivitiesByType('Contact', candidateId, filters, 0);
    //sort activities
    actList = LightningActivityAccessor.sort(actList,'date','DESC');
    activities = JSON.serialize(actList);
    
  }
  
  @AuraEnabled 
  public static MTX_MatrixWrapper fetchCandidateDetails(String candidateId, String matrixId){
    MTX_MatrixWrapper wrapper = new MTX_MatrixWrapper();
    wrapper.candidateRecord = MTX_MatrixAccessor.getCandidatesById(new List<String>{candidateId})[0];
    wrapper.matrixCandidate = MTX_MatrixAccessor.getMatrixCandidatesById(new List<String>{matrixId})[0];
    wrapper.currentMatrix = String.isNotBlank(wrapper.matrixCandidate.Matrix__c) ? MTX_MatrixAccessor.getMatrixById(wrapper.matrixCandidate.Matrix__c) : new MTX_Matrix__c( Name = Label.MTX_Candidates_Shared_with_Me );
    wrapper.preferredMobile = MTX_MatrixAccessor.getPreferedMobileForCandidate(wrapper.candidateRecord.Master_People__c);
    wrapper.candidates = MTX_MatrixAccessor.getMatrixCandidatesById(new List<String>{matrixId});
    
    List<Matrix_User_Setting__c> userSettings = MTX_MatrixAccessor.getSettingsForCurrentUser(UserInfo.getUserId());
    wrapper.userSettings = userSettings.isEmpty() == false ? userSettings[0] : MTX_MatrixService.createMatrixUserSetting(UserInfo.getUserId());
    /*** XEngine ***/
    XEngineUtils.postMatrixCandidatesEvent(wrapper.candidates, XEngineUtils.MTX_CAND_CANDIDATE_DETAILS);
    /*** XEngine ***/
    
    return wrapper;
  } 
  
  @AuraEnabled 
  public static MTX_Matrix_Note__c getNewMatrixNote(String candidateId){
    
    return new MTX_Matrix_Note__c(Candidate__c = candidateId);
  }
  
  @AuraEnabled 
  public static MTX_Matrix_Note__c saveNote(MTX_Matrix_Note__c note){
    
    return MTX_MatrixService.saveNote(note);
  }
  
  @AuraEnabled 
  public static MTX_Matrix_Note__c getNoteById(Id noteId){
    
/*** XEngine ***/
    XEngineUtils.postMatrixNoteEvent(noteId, XEngineUtils.NOTE_VIEW);
    /*** XEngine ***/
    return MTX_MatrixAccessor.getMatrixNoteById(noteId);
  }
  
  @AuraEnabled 
  public static void deleteSelectedNote(MTX_Matrix_Note__c note){
    
    MTX_MatrixService.deleteCandidateNote(note);
  }
}

Here are my test classes:

@isTest
public class MTX_MatrixDetailViewControllerTest {
  
  
  //create test data 
  @testSetup static void setup() {
    
    //setup FO full users (not inserted yet)
    List<User> matrixUsersToGivePermission = MatrixTestFactory.createMatrixUsers(2);
    
    //give FO full users matrix permission set (will insert the users)
    matrixUsersToGivePermission = MatrixTestFactory.giveMatrixPermission(matrixUsersToGivePermission);
    
    //setup spotlight
    MatrixTestFactory.setupEliseConnection();
    
  }
  
  
  static testMethod void gettingnewNote{
    List<Contact> candidates = MatrixTestFactory.getCandidates(); 
    List<User> matrixUsers = MatrixTestFactory.getMatrixUsers();
    Test.startTest();
    //MTX_Matrix_Note__c nt = new MTX_Matrix_Note__c();
    System.runAs(matrixUsers[0]) {
      MTX_MatrixService.getNewMatrixNote( candidates[0].Id );      
    }
    Test.stopTest();    
  } 
  
  static testMethod void savingtheNote{
    //create a method for for getting notes in MatrixTestFactory
    List<MTX_Matrix_Note__c> notes = MatrixTestFactory.getNotes();
    List<User> matrixUsers = MatrixTestFactory.getMatrixUsers();
    Test.startTest();
    //MTX_Matrix_Note__c nt = new MTX_Matrix_Note__c();
    System.runAs(matrixUsers[0]) {
      MTX_MatrixService.saveNote(notes[0] );      
    }  
    Test.stopTest();
  }
  
  static testMethod void deletingspecificNote{
    List<User> matrixUsers = MatrixTestFactory.getMatrixUsers();
    //create a method for for getting notes in MatrixTestFactory
    List<MTX_Matrix_Note__c> notes = MatrixTestFactory.getNotes();
    Test.startTest();
    //MTX_Matrix_Note__c nt = new MTX_Matrix_Note__c();
    System.runAs(matrixUsers[0]) {
      MTX_MatrixService.deleteCandidateNote(notes[0]);      
    }
    Test.stopTest();
  }
  static testMethod void retrievingNoteiD{
    List<User> matrixUsers = MatrixTestFactory.getMatrixUsers();
    //create a method for for getting notes in MatrixTestFactory
    List<MTX_Matrix_Note__c> notes = MatrixTestFactory.getNotes();
    Test.startTest();
    //MTX_Matrix_Note__c nt = new MTX_Matrix_Note__c();
    System.runAs(matrixUsers[0]) {
      MTX_MatrixService.deleteCandidateNote( notes[0]);      
    }
    Test.stopTest();
  }
  
}

Side note: Matrix Test Factory creates my test data, and when I call MTX_MatrixService.deleteCandidateNote, MTX_MatrixService.saveNote, MTX_MatrixService.getNewMatrixNote and MTX_MatrixAccessor.getMatrixNoteById, they are defined as

public static MTX_Matrix_Note__c saveNote(MTX_Matrix_Note__c note){
    boolean addNote;
    if(note.Id != null) { addNote = true; } else { addNote = false; }
    upsert note;
    /*** XEngine ***/
    if(!addNote){
      XEngineUtils.postMatrixNoteEvent(note.Id, XEngineUtils.NOTE_ADD);
    } else {
      XEngineUtils.postMatrixNoteEvent(note.Id, XEngineUtils.NOTE_UPDATE);
    }
     /*** XEngine ***/
     return note;
  }
  public static void deleteCandidateNote(MTX_Matrix_Note__c note){
    string matrixNoteJson = XEngineUtils.getMatrixNoteJson(note, XEngineUtils.NOTE_DELETE);
    delete note;
     /*** XEngine ***/
   XEngineUtils.postEventJson(matrixNoteJson);
    /*** XEngine ***/
  }
/*retrieves single matrix note content by note id*/
  public static MTX_Matrix_Note__c getMatrixNoteById(Id noteId){
    List<MTX_Matrix_Note__c> notes = new List<MTX_Matrix_Note__c>();
    notes = [SELECT Id, Note__c, CreatedById, CreatedBy.Name, LastModifiedDate FROM MTX_Matrix_Note__c WHERE Id =: noteId];
    return notes.isEmpty() == false ? notes[0] : null;
  }
```

public with sharing class MTX_MatrixDetailViewController {
  public transient String activities {get;set;}
  public MTX_MatrixDetailViewController(){
    
    String candidateId = ApexPages.currentPage().getParameters().get('id');
     Map<String, String> filters = new Map<String, String>();
    
    List<LightningActivity> actList = LightningActivityAccessor.getLightningActivitiesByType('Contact', candidateId, filters, 0);
    //sort activities
    actList = LightningActivityAccessor.sort(actList,'date','DESC');
    activities = JSON.serialize(actList);
    
  }
  
  @AuraEnabled 
  public static MTX_MatrixWrapper fetchCandidateDetails(String candidateId, String matrixId){
    MTX_MatrixWrapper wrapper = new MTX_MatrixWrapper();
    wrapper.candidateRecord = MTX_MatrixAccessor.getCandidatesById(new List<String>{candidateId})[0];
    wrapper.matrixCandidate = MTX_MatrixAccessor.getMatrixCandidatesById(new List<String>{matrixId})[0];
    wrapper.currentMatrix = String.isNotBlank(wrapper.matrixCandidate.Matrix__c) ? MTX_MatrixAccessor.getMatrixById(wrapper.matrixCandidate.Matrix__c) : new MTX_Matrix__c( Name = Label.MTX_Candidates_Shared_with_Me );
    wrapper.preferredMobile = MTX_MatrixAccessor.getPreferedMobileForCandidate(wrapper.candidateRecord.Master_People__c);
    wrapper.candidates = MTX_MatrixAccessor.getMatrixCandidatesById(new List<String>{matrixId});
    
    List<Matrix_User_Setting__c> userSettings = MTX_MatrixAccessor.getSettingsForCurrentUser(UserInfo.getUserId());
    wrapper.userSettings = userSettings.isEmpty() == false ? userSettings[0] : MTX_MatrixService.createMatrixUserSetting(UserInfo.getUserId());
    /*** XEngine ***/
    XEngineUtils.postMatrixCandidatesEvent(wrapper.candidates, XEngineUtils.MTX_CAND_CANDIDATE_DETAILS);
    /*** XEngine ***/
    
    return wrapper;
  } 
  
  @AuraEnabled 
  public static MTX_Matrix_Note__c getNewMatrixNote(String candidateId){
    
    return new MTX_Matrix_Note__c(Candidate__c = candidateId);
  }
  
  @AuraEnabled 
  public static MTX_Matrix_Note__c saveNote(MTX_Matrix_Note__c note){
    
    return MTX_MatrixService.saveNote(note);
  }
  
  @AuraEnabled 
  public static MTX_Matrix_Note__c getNoteById(Id noteId){
    
/*** XEngine ***/
    XEngineUtils.postMatrixNoteEvent(noteId, XEngineUtils.NOTE_VIEW);
    /*** XEngine ***/
    return MTX_MatrixAccessor.getMatrixNoteById(noteId);
  }
  
  @AuraEnabled 
  public static void deleteSelectedNote(MTX_Matrix_Note__c note){
    
    MTX_MatrixService.deleteCandidateNote(note);
  }
}

Here are my test classes:

@isTest
public class MTX_MatrixDetailViewControllerTest {
  
  
  //create test data 
  @testSetup static void setup() {
    
    //setup FO full users (not inserted yet)
    List<User> matrixUsersToGivePermission = MatrixTestFactory.createMatrixUsers(2);
    
    //give FO full users matrix permission set (will insert the users)
    matrixUsersToGivePermission = MatrixTestFactory.giveMatrixPermission(matrixUsersToGivePermission);
    
    //setup spotlight
    MatrixTestFactory.setupEliseConnection();
    
  }
  
  
  static testMethod void gettingnewNote{
    List<Contact> candidates = MatrixTestFactory.getCandidates(); 
    List<User> matrixUsers = MatrixTestFactory.getMatrixUsers();
    Test.startTest();
    //MTX_Matrix_Note__c nt = new MTX_Matrix_Note__c();
    System.runAs(matrixUsers[0]) {
      MTX_MatrixService.getNewMatrixNote( candidates[0].Id );      
    }
    Test.stopTest();    
  } 
  
  static testMethod void savingtheNote{
    //create a method for for getting notes in MatrixTestFactory
    List<MTX_Matrix_Note__c> notes = MatrixTestFactory.getNotes();
    List<User> matrixUsers = MatrixTestFactory.getMatrixUsers();
    Test.startTest();
    //MTX_Matrix_Note__c nt = new MTX_Matrix_Note__c();
    System.runAs(matrixUsers[0]) {
      MTX_MatrixService.saveNote(notes[0] );      
    }  
    Test.stopTest();
  }
  
  static testMethod void deletingspecificNote{
    List<User> matrixUsers = MatrixTestFactory.getMatrixUsers();
    //create a method for for getting notes in MatrixTestFactory
    List<MTX_Matrix_Note__c> notes = MatrixTestFactory.getNotes();
    Test.startTest();
    //MTX_Matrix_Note__c nt = new MTX_Matrix_Note__c();
    System.runAs(matrixUsers[0]) {
      MTX_MatrixService.deleteCandidateNote(notes[0]);      
    }
    Test.stopTest();
  }
  static testMethod void retrievingNoteiD{
    List<User> matrixUsers = MatrixTestFactory.getMatrixUsers();
    //create a method for for getting notes in MatrixTestFactory
    List<MTX_Matrix_Note__c> notes = MatrixTestFactory.getNotes();
    Test.startTest();
    //MTX_Matrix_Note__c nt = new MTX_Matrix_Note__c();
    System.runAs(matrixUsers[0]) {
      MTX_MatrixService.deleteCandidateNote( notes[0]);      
    }
    Test.stopTest();
  }
  
}

Side note: Matrix Test Factory creates my test data, and when I call MTX_MatrixService.deleteCandidateNote, MTX_MatrixService.saveNote, MTX_MatrixService.getNewMatrixNote and MTX_MatrixAccessor.getMatrixNoteById, they are defined as

public static MTX_Matrix_Note__c saveNote(MTX_Matrix_Note__c note){
    boolean addNote;
    if(note.Id != null) { addNote = true; } else { addNote = false; }
    upsert note;
    /*** XEngine ***/
    if(!addNote){
      XEngineUtils.postMatrixNoteEvent(note.Id, XEngineUtils.NOTE_ADD);
    } else {
      XEngineUtils.postMatrixNoteEvent(note.Id, XEngineUtils.NOTE_UPDATE);
    }
     /*** XEngine ***/
     return note;
  }
  public static void deleteCandidateNote(MTX_Matrix_Note__c note){
    string matrixNoteJson = XEngineUtils.getMatrixNoteJson(note, XEngineUtils.NOTE_DELETE);
    delete note;
     /*** XEngine ***/
   XEngineUtils.postEventJson(matrixNoteJson);
    /*** XEngine ***/
  }
/*retrieves single matrix note content by note id*/
  public static MTX_Matrix_Note__c getMatrixNoteById(Id noteId){
    List<MTX_Matrix_Note__c> notes = new List<MTX_Matrix_Note__c>();
    notes = [SELECT Id, Note__c, CreatedById, CreatedBy.Name, LastModifiedDate FROM MTX_Matrix_Note__c WHERE Id =: noteId];
    return notes.isEmpty() == false ? notes[0] : null;
  }
```

public with sharing class MTX_MatrixDetailViewController {
 
    //sort activities
    actList = LightningActivityAccessor.sort(actList,'date','DESC');
    activities = JSON.serialize(actList);
    
  }
  
  

I have this controller, in which I am trying to write good test classes. I have some test cases. Any corrections/advice are appreciated to make them better.

Here are my test classes,

I have this controller and some test cases. Any corrections/advice are appreciated to make them better.

Here are my test classes: