I am a beginner in apex. I have written this kind of test, but it makes some mistakes, someone can tell me what is wrong or how to do it better.
I only have 60% coverage.

The contacts to which a template with an attached file will be sent are selected.
The file is not mandatory.
In the custom button, only the subject and body are written and the template is not taken.

These are my codes.
****Visualforce*****

<apex:page controller="ControllerEnviaEmailInscripciones" doctype="html-5.0" language="es"> 
    <apex:form id="frm" acceptcharset="UTF-8">
      <apex:pageBlock >
          
          <apex:pageBlockSection columns="1">
              <apex:pageBlockTable value="{!models}" var="m">
                <apex:column headerValue="Acción" >
                    <apex:inputcheckbox value="{!m.flag}"/> 
                </apex:column>
                <apex:column headerValue="Nombre de la Inscripción">
                       <apex:outputField value="{!m.std.Name}"/>
                </apex:column>
                <apex:column headerValue="Contacto">
                         <apex:outputField value="{!m.std.Contacto__r.Name}"/>
                </apex:column>
                <apex:column headerValue="Cliente">
                        <apex:outputField value="{!m.std.Cliente__r.Name}"/> 
                </apex:column>
                <apex:column headerValue="Email">
                       <apex:outputField value="{!m.std.CorreoElectronico__c}"/>
                </apex:column>
                <apex:column headerValue="Número de Inscripción">
                        <apex:outputField value="{!m.std.NumeroInscripcion__c}"/>
                </apex:column>  
                <apex:column headerValue="Estado">
                        <apex:outputField value="{!m.std.Estado__c}"/>
                </apex:column>
              </apex:pageBlockTable>      
          </apex:pageBlockSection>
          
           <apex:pageBlock > 
        <!--  <apex:outputLabel value="Nombre del Archivo" for="fileName"/>
              <apex:inputText value="{!attachment.name}" id="fileName"/> -->
              <apex:outputLabel value="Archivo" for="file"/>
              <apex:inputFile value="{!attachment.body}" filename="{!attachment.name}" id="file" />
              <apex:messages style="font-size: 100%; color: blue;"/>
           </apex:pageBlock> 
       <!------------------------Sección de Email Personalizado--------------------------->  
           <apex:pageBlock > 
              <apex:commandButton value="{!Personalizaremail}" action="{!click}"/>     
                
               <apex:pageBlockSection id="thePanel" rendered="{!thePanel}">
                  <apex:pageBlockSectionItem >
                      <a style="font-family: Arial; font-size: 10pt;">Asunto:</a>
                      <apex:inputText value="{!asunto}" style="font-family: Arial; font-size: 10pt;" size="80" /> 
                  </apex:pageBlockSectionItem><br/> 
                  
                  <apex:pageBlockSectionItem >&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  	  <apex:inputTextarea value="{!texto}" rows="15" cols="91" lang="es"/> <!-- lang="es" richText="true"-->
                  </apex:pageBlockSectionItem><br/>
               </apex:pageBlockSection> 
               
           </apex:pageBlock> 
          
          <apex:pageblockButtons >
               <apex:commandButton value="Enviar Email" action="{!send}" onclick="if(!confirm('Estás seguro de enviarlo?')) return false;"/>
          </apex:pageblockButtons>
     
      </apex:pageBlock> 
  </apex:form>
</apex:page>

***Controller***​​​​​​​

public class ControllerEnviaEmailInscripciones{

     public String Personalizaremail {get; set;}
     public Boolean thePanel         {get; set;}
     public String asunto            {get; set;}
     public String texto             {get; set;}
    
     public Attachment attachment {
        get {
            if (attachment == null)
                attachment = new Attachment();
            return attachment;
        }
        set;
     }
        
    public class ModelClass {
        public Inscripcion__c std  {get; set;}
        public Boolean flag        {get; set;}
    
    ModelClass(Inscripcion__c std) {
            this.std = std;
         // this.flag = true;
         }
     } 

    public List<ModelClass> models {get; set;}

    public ControllerEnviaEmailInscripciones() {
       Personalizaremail ='Email personalizado';
       String IdCapacitacion = System.currentPageReference().getParameters().get('id');
       models = new List<ModelClass>();
       for (Inscripcion__c c : [SELECT Id, Capacitacion__c, Estado__c, Name, NumeroInscripcion__c, Contacto__r.Name, CorreoElectronico__c, Cliente__r.Name 
                                FROM Inscripcion__c WHERE Capacitacion__c =:IdCapacitacion AND Contacto__r.email != NULL order by name limit 100]) {
            models.add(new ModelClass(c));
        }
     }
  
   public void click(){
       if (Personalizaremail == 'Email personalizado'){
           Personalizaremail ='Ocultar sección';
           thePanel = true;
       } else if (Personalizaremail == 'Ocultar sección') {
           Personalizaremail ='Email personalizado';
           thePanel = false;
       }
    }
    
    public PageReference send() {
 if (Personalizaremail == 'Email personalizado')  {        
     try {  
          EmailTemplate template = [ Select Id from EmailTemplate where developername = 'Capacitacion'];
         
            List<Messaging.Emailfileattachment> fileAttachments = new List<Messaging.Emailfileattachment>();
            Messaging.Emailfileattachment attachmentForMail = new Messaging.Emailfileattachment();
            attachmentForMail.setFileName(attachment.name); 
            attachmentForMail.setBody(attachment.Body);
            fileAttachments.add(attachmentForMail);
    
              Messaging.SingleEmailMessage[] messages = new Messaging.SingleEmailMessage[] {};
                for (ModelClass m : models) {
                    if (m.flag) {
                        Messaging.SingleEmailMessage message = new Messaging.SingleEmailMessage();
                        message.setTargetObjectId(m.Std.Contacto__r.Id);
                        message.setTemplateId(template.Id);
                           if(attachment.name !=NULL && attachment.Body !=NULL) {//verificamos que hay un archivo adjunto
                              message.setFileAttachments(fileAttachments);
                          } 
                        messages.add(message);
                     }
                  }
             Messaging.sendEmail(messages, true );
            ApexPages.addmessage(new ApexPages.message(ApexPages.severity.CONFIRM,'Email enviado correctamente.'));
        } Catch(Exception e){
                e.getMessage();
            } finally {
             attachment.Body = null;
            } 
   } else if (Personalizaremail == 'Ocultar sección'){   //termina if (Personalizaremail == 'Ocultar sección')
         try {  
         
            List<Messaging.Emailfileattachment> fileAttachments = new List<Messaging.Emailfileattachment>();
            Messaging.Emailfileattachment attachmentForMail = new Messaging.Emailfileattachment();
            attachmentForMail.setFileName(attachment.name); 
            attachmentForMail.setBody(attachment.Body);
            fileAttachments.add(attachmentForMail);
    
              Messaging.SingleEmailMessage[] messages = new Messaging.SingleEmailMessage[] {};
                for (ModelClass m : models) {
                    if (m.flag) {
                        Messaging.SingleEmailMessage message = new Messaging.SingleEmailMessage();
                        message.setTargetObjectId(m.Std.Contacto__r.Id);
                        message.setSubject(asunto);
                        message.setPlainTextBody(texto);
                          if(attachment.name !=NULL && attachment.Body !=NULL) {
                              message.setFileAttachments(fileAttachments);
                          } 
                        messages.add(message);
                     }
                  }
             Messaging.sendEmail(messages, true );
            ApexPages.addmessage(new ApexPages.message(ApexPages.severity.CONFIRM,'Email enviado correctamente.'));
        } Catch(Exception e){
                e.getMessage();
            } finally {
             attachment.Body = null;
            } 
     }
    return null;  
   } 
   
}

***test class****
 

private class Test_ControllerEnviaEmailInscripciones {
  
    @isTest static void enviaEmail(){
        
     Account a = New Account();
        a.Name ='Alfredo';
        a.NombreComercial__c ='Alberto';
        a.GeneroCapital__c ='Hombre';
        insert (a);
        
     List<Contact> contactList = new List<Contact>();
        contactList.add(Util.createContact(a.Id, 'test contact2', 'email1@test.com', false));
        contactList.add(Util.createContact(a.Id, 'test contact2', 'email2@test.com', false));
        insert contactList;
     
  Test.startTest();
        
     Capacitacion__c cap = New Capacitacion__c();
        cap.Name ='Multple capacitacion';
        cap.TipoCapacitacion__c='Programa';
        cap.ClasificacionFormacion__c='Principiante';
        cap.AreaPromueveCurso__c='CACEX';
        cap.LugarImparte__c='Procomer';
        cap.FechaInicial__c= System.today() + 4;
        insert(cap);
       
      Inscripcion__c insc = New Inscripcion__c();
        insc.Capacitacion__c = cap.Id;
        insc.Cliente__c=a.Id;
        insc.Contacto__c=contactList[0].Id;
        insc.Name =contactList[0].Name;
        insc.CorreoElectronico__c=contactList[0].Email;
        insc.Estado__c='Asiste';
        insc.RegistroAsistencia__c= System.today()+ 1;
        insc.FechaConfirmacion__c=  System.today() + 2;
        insc.NumeroInscripcion__c= '1';
        insert(insc);
        
        Attachment attach=new Attachment();   	
    	attach.Name='Unit Test Attachment';
    	Blob bodyBlob=Blob.valueOf('Unit Test Attachment Body');
    	attach.body=bodyBlob;
        attach.parentId=cap.id;
        insert attach;
       
        PageReference pref = Page.EnviaEmailInscripciones;
        pref.getParameters().put('id', cap.id);
        Test.setCurrentPage(pref);
        
        ControllerEnviaEmailInscripciones envEmail = New ControllerEnviaEmailInscripciones();
        envEmail.texto ='test envía';
        envEmail.asunto='test asunto';
          pref = envEmail.send();
       
        envEmail.click();
 
        Test.stopTest();    
    }
   
    
    
    /***********************************test 2 - Parte seccion oculta *************************************************/

    
     @isTest static void enviaEmail2(){
        
     Account a = New Account();
        a.Name ='Alfredo';
        a.NombreComercial__c ='Alberto';
        a.GeneroCapital__c ='Hombre';
        insert (a);
        
     List<Contact> contactList = new List<Contact>();
        contactList.add(Util.createContact(a.Id, 'test contact1', 'email1@test.com', false));
        contactList.add(Util.createContact(a.Id, 'test contact2', 'email2@test.com', false));
        insert contactList;
     
  Test.startTest();
        
     Capacitacion__c cap = New Capacitacion__c();
        cap.Name ='Multple capacitacion';
        cap.TipoCapacitacion__c='Programa';
        cap.ClasificacionFormacion__c='Principiante';
        cap.AreaPromueveCurso__c='CACEX';
        cap.LugarImparte__c='Procomer';
        cap.FechaInicial__c= System.today() + 4;
        insert(cap);
       
        Inscripcion__c insc = New Inscripcion__c();
        insc.Capacitacion__c = cap.Id;
        insc.Cliente__c=a.Id;
        insc.Contacto__c=contactList[0].Id;
        insc.Name =contactList[0].Name;
        insc.CorreoElectronico__c=contactList[0].Email;
        insc.Estado__c='Asiste';
        insc.RegistroAsistencia__c= System.today()+ 1;
        insc.FechaConfirmacion__c=  System.today() + 2;
        insc.NumeroInscripcion__c= '1';
        insert (insc); 
       
       Inscripcion__c insc2 = New Inscripcion__c();
        insc2.Capacitacion__c = cap.Id;
        insc2.Cliente__c=a.Id;
        insc2.Contacto__c=contactList[1].Id;
        insc2.Name =contactList[1].Name;
        insc2.CorreoElectronico__c=contactList[1].Email;
        insc2.Estado__c='Asiste';
        insc2.RegistroAsistencia__c= System.today()+ 1;
        insc2.FechaConfirmacion__c=  System.today() + 2;
        insc2.NumeroInscripcion__c= '2';
        insert (insc2); 
         
        Attachment attach=new Attachment();   	
    	attach.Name='Prueba Adjunto';
    	Blob bodyBlob=Blob.valueOf('Cuerpo del Archivo');
    	attach.body=bodyBlob;
        attach.parentId=cap.id;
        insert attach;
        
       // System.currentPageReference().getParameters().put('id', cap.Id);
        PageReference pref = Page.EnviaEmailInscripciones;
        pref.getParameters().put('id', cap.id);
        Test.setCurrentPage(pref);
       
        ControllerEnviaEmailInscripciones envEmail = New ControllerEnviaEmailInscripciones();
         
        envEmail.texto ='test envía';
        envEmail.asunto='test asunto';
        envEmail.Personalizaremail = 'Ocultar sección';
       
       pref = envEmail.send();
        envEmail.click();

        Test.stopTest();    
    }
}

I am a beginner in apex. I have written this kind of test, but it makes some mistakes, someone can tell me what is wrong or how to do it better.
I only have 60% coverage...


The contacts to which a template with an attached file will be sent are selected.
The file is not mandatory.
In the custom button, only the subject and body are written and the template is not taken.

These are my codes.
****Visualforce*****

<apex:page controller="ControllerEnviaEmailInscripciones" doctype="html-5.0" language="es"> 
    <apex:form id="frm" acceptcharset="UTF-8">
      <apex:pageBlock >
          
          <apex:pageBlockSection columns="1">
              <apex:pageBlockTable value="{!models}" var="m">
                <apex:column headerValue="Acción" >
                    <apex:inputcheckbox value="{!m.flag}"/> 
                </apex:column>
                <apex:column headerValue="Nombre de la Inscripción">
                       <apex:outputField value="{!m.std.Name}"/>
                </apex:column>
                <apex:column headerValue="Contacto">
                         <apex:outputField value="{!m.std.Contacto__r.Name}"/>
                </apex:column>
                <apex:column headerValue="Cliente">
                        <apex:outputField value="{!m.std.Cliente__r.Name}"/> 
                </apex:column>
                <apex:column headerValue="Email">
                       <apex:outputField value="{!m.std.CorreoElectronico__c}"/>
                </apex:column>
                <apex:column headerValue="Número de Inscripción">
                        <apex:outputField value="{!m.std.NumeroInscripcion__c}"/>
                </apex:column>  
                <apex:column headerValue="Estado">
                        <apex:outputField value="{!m.std.Estado__c}"/>
                </apex:column>
              </apex:pageBlockTable>      
          </apex:pageBlockSection>
          
           <apex:pageBlock > 
        <!--  <apex:outputLabel value="Nombre del Archivo" for="fileName"/>
              <apex:inputText value="{!attachment.name}" id="fileName"/> -->
              <apex:outputLabel value="Archivo" for="file"/>
              <apex:inputFile value="{!attachment.body}" filename="{!attachment.name}" id="file" />
              <apex:messages style="font-size: 100%; color: blue;"/>
           </apex:pageBlock> 
       <!------------------------Sección de Email Personalizado--------------------------->  
           <apex:pageBlock > 
              <apex:commandButton value="{!Personalizaremail}" action="{!click}"/>     
                
               <apex:pageBlockSection id="thePanel" rendered="{!thePanel}">
                  <apex:pageBlockSectionItem >
                      <a style="font-family: Arial; font-size: 10pt;">Asunto:</a>
                      <apex:inputText value="{!asunto}" style="font-family: Arial; font-size: 10pt;" size="80" /> 
                  </apex:pageBlockSectionItem><br/> 
                  
                  <apex:pageBlockSectionItem >&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                  	  <apex:inputTextarea value="{!texto}" rows="15" cols="91" lang="es"/> <!-- lang="es" richText="true"-->
                  </apex:pageBlockSectionItem><br/>
               </apex:pageBlockSection> 
               
           </apex:pageBlock> 
          
          <apex:pageblockButtons >
               <apex:commandButton value="Enviar Email" action="{!send}" onclick="if(!confirm('Estás seguro de enviarlo?')) return false;"/>
          </apex:pageblockButtons>
     
      </apex:pageBlock> 
  </apex:form>
</apex:page>

***Controller***

public class ControllerEnviaEmailInscripciones{

     public String Personalizaremail {get; set;}
     public Boolean thePanel         {get; set;}
     public String asunto            {get; set;}
     public String texto             {get; set;}
    
     public Attachment attachment {
        get {
            if (attachment == null)
                attachment = new Attachment();
            return attachment;
        }
        set;
     }
        
    public class ModelClass {
        public Inscripcion__c std  {get; set;}
        public Boolean flag        {get; set;}
    
    ModelClass(Inscripcion__c std) {
            this.std = std;
         // this.flag = true;
         }
     } 

    public List<ModelClass> models {get; set;}

    public ControllerEnviaEmailInscripciones() {
       Personalizaremail ='Email personalizado';
       String IdCapacitacion = System.currentPageReference().getParameters().get('id');
       models = new List<ModelClass>();
       for (Inscripcion__c c : [SELECT Id, Capacitacion__c, Estado__c, Name, NumeroInscripcion__c, Contacto__r.Name, CorreoElectronico__c, Cliente__r.Name 
                                FROM Inscripcion__c WHERE Capacitacion__c =:IdCapacitacion AND Contacto__r.email != NULL order by name limit 100]) {
            models.add(new ModelClass(c));
        }
     }
  
   public void click(){
       if (Personalizaremail == 'Email personalizado'){
           Personalizaremail ='Ocultar sección';
           thePanel = true;
       } else if (Personalizaremail == 'Ocultar sección') {
           Personalizaremail ='Email personalizado';
           thePanel = false;
       }
    }
    
    public PageReference send() {
 if (Personalizaremail == 'Email personalizado')  {        
     try {  
          EmailTemplate template = [ Select Id from EmailTemplate where developername = 'Capacitacion'];
         
            List<Messaging.Emailfileattachment> fileAttachments = new List<Messaging.Emailfileattachment>();
            Messaging.Emailfileattachment attachmentForMail = new Messaging.Emailfileattachment();
            attachmentForMail.setFileName(attachment.name); 
            attachmentForMail.setBody(attachment.Body);
            fileAttachments.add(attachmentForMail);
    
              Messaging.SingleEmailMessage[] messages = new Messaging.SingleEmailMessage[] {};
                for (ModelClass m : models) {
                    if (m.flag) {
                        Messaging.SingleEmailMessage message = new Messaging.SingleEmailMessage();
                        message.setTargetObjectId(m.Std.Contacto__r.Id);
                        message.setTemplateId(template.Id);
                           if(attachment.name !=NULL && attachment.Body !=NULL) {//verificamos que hay un archivo adjunto
                              message.setFileAttachments(fileAttachments);
                          } 
                        messages.add(message);
                     }
                  }
             Messaging.sendEmail(messages, true );
            ApexPages.addmessage(new ApexPages.message(ApexPages.severity.CONFIRM,'Email enviado correctamente.'));
        } Catch(Exception e){
                e.getMessage();
            } finally {
             attachment.Body = null;
            } 
   } else if (Personalizaremail == 'Ocultar sección'){   //termina if (Personalizaremail == 'Ocultar sección')
         try {  
         
            List<Messaging.Emailfileattachment> fileAttachments = new List<Messaging.Emailfileattachment>();
            Messaging.Emailfileattachment attachmentForMail = new Messaging.Emailfileattachment();
            attachmentForMail.setFileName(attachment.name); 
            attachmentForMail.setBody(attachment.Body);
            fileAttachments.add(attachmentForMail);
    
              Messaging.SingleEmailMessage[] messages = new Messaging.SingleEmailMessage[] {};
                for (ModelClass m : models) {
                    if (m.flag) {
                        Messaging.SingleEmailMessage message = new Messaging.SingleEmailMessage();
                        message.setTargetObjectId(m.Std.Contacto__r.Id);
                        message.setSubject(asunto);
                        message.setPlainTextBody(texto);
                          if(attachment.name !=NULL && attachment.Body !=NULL) {
                              message.setFileAttachments(fileAttachments);
                          } 
                        messages.add(message);
                     }
                  }
             Messaging.sendEmail(messages, true );
            ApexPages.addmessage(new ApexPages.message(ApexPages.severity.CONFIRM,'Email enviado correctamente.'));
        } Catch(Exception e){
                e.getMessage();
            } finally {
             attachment.Body = null;
            } 
     }
    return null;  
   } 
   
}

***test class****
 

private class Test_ControllerEnviaEmailInscripciones {
  
    @isTest static void enviaEmail(){
        
     Account a = New Account();
        a.Name ='Alfredo';
        a.NombreComercial__c ='Alberto';
        a.GeneroCapital__c ='Hombre';
        insert (a);
        
     List<Contact> contactList = new List<Contact>();
        contactList.add(Util.createContact(a.Id, 'test contact2', 'email1@test.com', false));
        contactList.add(Util.createContact(a.Id, 'test contact2', 'email2@test.com', false));
        insert contactList;
     
  Test.startTest();
        
     Capacitacion__c cap = New Capacitacion__c();
        cap.Name ='Multple capacitacion';
        cap.TipoCapacitacion__c='Programa';
        cap.ClasificacionFormacion__c='Principiante';
        cap.AreaPromueveCurso__c='CACEX';
        cap.LugarImparte__c='Procomer';
        cap.FechaInicial__c= System.today() + 4;
        insert(cap);
       
      Inscripcion__c insc = New Inscripcion__c();
        insc.Capacitacion__c = cap.Id;
        insc.Cliente__c=a.Id;
        insc.Contacto__c=contactList[0].Id;
        insc.Name =contactList[0].Name;
        insc.CorreoElectronico__c=contactList[0].Email;
        insc.Estado__c='Asiste';
        insc.RegistroAsistencia__c= System.today()+ 1;
        insc.FechaConfirmacion__c=  System.today() + 2;
        insc.NumeroInscripcion__c= '1';
        insert(insc);
        
        Attachment attach=new Attachment();   	
    	attach.Name='Unit Test Attachment';
    	Blob bodyBlob=Blob.valueOf('Unit Test Attachment Body');
    	attach.body=bodyBlob;
        attach.parentId=cap.id;
        insert attach;
       
        PageReference pref = Page.EnviaEmailInscripciones;
        pref.getParameters().put('id', cap.id);
        Test.setCurrentPage(pref);
        
        ControllerEnviaEmailInscripciones envEmail = New ControllerEnviaEmailInscripciones();
        envEmail.texto ='test envía';
        envEmail.asunto='test asunto';
          pref = envEmail.send();
       
        envEmail.click();
 
        Test.stopTest();    
    }
   
    
    
    /***********************************test 2 - Parte seccion oculta *************************************************/

    
     @isTest static void enviaEmail2(){
        
     Account a = New Account();
        a.Name ='Alfredo';
        a.NombreComercial__c ='Alberto';
        a.GeneroCapital__c ='Hombre';
        insert (a);
        
     List<Contact> contactList = new List<Contact>();
        contactList.add(Util.createContact(a.Id, 'test contact1', 'email1@test.com', false));
        contactList.add(Util.createContact(a.Id, 'test contact2', 'email2@test.com', false));
        insert contactList;
     
  Test.startTest();
        
     Capacitacion__c cap = New Capacitacion__c();
        cap.Name ='Multple capacitacion';
        cap.TipoCapacitacion__c='Programa';
        cap.ClasificacionFormacion__c='Principiante';
        cap.AreaPromueveCurso__c='CACEX';
        cap.LugarImparte__c='Procomer';
        cap.FechaInicial__c= System.today() + 4;
        insert(cap);
       
        Inscripcion__c insc = New Inscripcion__c();
        insc.Capacitacion__c = cap.Id;
        insc.Cliente__c=a.Id;
        insc.Contacto__c=contactList[0].Id;
        insc.Name =contactList[0].Name;
        insc.CorreoElectronico__c=contactList[0].Email;
        insc.Estado__c='Asiste';
        insc.RegistroAsistencia__c= System.today()+ 1;
        insc.FechaConfirmacion__c=  System.today() + 2;
        insc.NumeroInscripcion__c= '1';
        insert (insc); 
       
       Inscripcion__c insc2 = New Inscripcion__c();
        insc2.Capacitacion__c = cap.Id;
        insc2.Cliente__c=a.Id;
        insc2.Contacto__c=contactList[1].Id;
        insc2.Name =contactList[1].Name;
        insc2.CorreoElectronico__c=contactList[1].Email;
        insc2.Estado__c='Asiste';
        insc2.RegistroAsistencia__c= System.today()+ 1;
        insc2.FechaConfirmacion__c=  System.today() + 2;
        insc2.NumeroInscripcion__c= '2';
        insert (insc2); 
         
        Attachment attach=new Attachment();   	
    	attach.Name='Prueba Adjunto';
    	Blob bodyBlob=Blob.valueOf('Cuerpo del Archivo');
    	attach.body=bodyBlob;
        attach.parentId=cap.id;
        insert attach;
        
       // System.currentPageReference().getParameters().put('id', cap.Id);
        PageReference pref = Page.EnviaEmailInscripciones;
        pref.getParameters().put('id', cap.id);
        Test.setCurrentPage(pref);
       
        ControllerEnviaEmailInscripciones envEmail = New ControllerEnviaEmailInscripciones();
         
        envEmail.texto ='test envía';
        envEmail.asunto='test asunto';
        envEmail.Personalizaremail = 'Ocultar sección';
       
       pref = envEmail.send();
        envEmail.click();

        Test.stopTest();    
    }
}

​​​​​​​

I am a beginner in apex. I have written this kind of test, but it makes some mistakes, someone can tell me what is wrong or how to do it better.
I only have 35% coverage
These are my codes.

***** Code Visualforce ****

<apex:page controller="deleteRowsExample" action="{!onloadmethod}"> <!--- action="{!onloadmethod}"--->
<apex:form >
<apex:pageBlock >
    <apex:commandbutton value="Add Contact" action="{!addContact}" immediate="true"/>
    <apex:commandButton value="Save Changes" action="{!saveChanges}"/>
  <!-- Display some account information -->  
  <apex:pageBlockSection columns="1">
      <apex:outputField value="{!accountRec.Name}"/>
      <apex:outputField value="{!accountRec.OwnerId}"/>
  </apex:pageBlockSection>
  
  <!-- Display the related contacts for the Account -->
  <apex:pageblocktable value="{!Contacts}" var="con"> <apex:variable value="{!0}" var="cnt"/>
      <apex:column headervalue="Action">
          <apex:commandlink value="Remove" action="{!removeContact}" immediate="true">
              <!-- Pass the row number to the controller so that we know which row to remove -->
              <apex:param name="index" value="{!cnt}"/>
          </apex:commandlink> 
          <apex:variable var="cnt" value="{!cnt+1}"/>              
      </apex:column>  
      <apex:column headerValue="first Name">
          <apex:inputfield value="{!con.FirstName}"/>
      </apex:column>    
      <apex:column headerValue="Last Name">
          <apex:inputfield value="{!con.LastName}"/>
      </apex:column>     
  </apex:pageblocktable>
  
</apex:pageBlock>  
</apex:form>    
</apex:page>

 

*****controller******
 

public class deleteRowsExample {

public List<Contact> allContactList = new List<Contact>();
public List<Contact> deleteContactList = new List<Contact>();
    
public Account accountRec {get;set;}

//Called when the page loads initially from the "action" method on the apex:page. Populates the Account record and the releated contact list
public void onloadmethod(){

     String aid = System.currentPageReference().getParameters().get('id');
     accountRec = [Select Id,OwnerId,Name,Type,Phone,Website from Account where Id=:aid]; 
     allContactList = [Select Id,FirstName,LastName from Contact where AccountId=:accountRec.Id];
}
//Send the list of contacts to the visualforce page
public List<Contact> getContacts(){
    return allContactList;
}

//Add a temporary contact to the table. Not saved to the database
public void addContact(){
    Contact c = new Contact();
    allContactList.add(c);
}

//Remove a contact from the table.
public void removeContact(){
    Integer indexVal = Integer.valueof(system.currentpagereference().getparameters().get('index'));
    //If the contact is an existing contact then add it to the list to delete from the database
    if(allContactList[indexVal - 1].Id != null)
        deleteContactList.add(allContactList[indexVal - 1]);
    //Remove the contact from the table    
    allContactList.remove(indexVal - 1);            
}    
public void saveChanges(){
    for(Integer i=0; i<allContactList.size(); i++) {
			upsert allContactList; //insert allContactList;
		} 

    //delete the contacts that were removed
    if(deleteContactList.size() > 0){
        delete deleteContactList;
    }
}    
    
}

 

*****Test Class*****
 

@isTest
private class testdeleteRowsExample_Test {
  @isTest static void agregacuentas(){
   Test.startTest();   
 Account acc = new Account();
        acc.Name = 'TestCuenta';
        insert(acc);   
           
        Contact con = new Contact();
        con.AccountId = acc.Id;
        con.FirstName = 'Pedro';
        con.LastName = 'Lopez';
        con.MailingPostalCode = '45546';
        insert (con);
        
        Contact con2 = new Contact();
        con2.AccountId = acc.Id;
        con2.FirstName = 'Rosa';
        con2.LastName = 'Croy';
        con.MailingPostalCode = '66546';
        insert (con2); 
 
deleteRowsExample Rows = new deleteRowsExample();
            Rows.addContact();
            Rows.onloadmethod(); 
            Rows.getContacts();
            Rows.saveChanges();
            Rows.removeContact();
Test.stopTest();
    }
}

I am a beginner in apex. I have written this kind of test, but it makes some mistakes, someone can tell me what is wrong or how to do it better.
I only have 35% coverage
These are my codes.

***** Code Visualforce ****

<apex:page controller="deleteRowsExample" action="{!onloadmethod}"> <!--- action="{!onloadmethod}"--->
<apex:form >
<apex:pageBlock >
    <apex:commandbutton value="Add Contact" action="{!addContact}" immediate="true"/>
    <apex:commandButton value="Save Changes" action="{!saveChanges}"/>
  <!-- Display some account information -->  
  <apex:pageBlockSection columns="1">
      <apex:outputField value="{!accountRec.Name}"/>
      <apex:outputField value="{!accountRec.OwnerId}"/>
  </apex:pageBlockSection>
  
  <!-- Display the related contacts for the Account -->
  <apex:pageblocktable value="{!Contacts}" var="con"> <apex:variable value="{!0}" var="cnt"/>
      <apex:column headervalue="Action">
          <apex:commandlink value="Remove" action="{!removeContact}" immediate="true">
              <!-- Pass the row number to the controller so that we know which row to remove -->
              <apex:param name="index" value="{!cnt}"/>
          </apex:commandlink> 
          <apex:variable var="cnt" value="{!cnt+1}"/>              
      </apex:column>  
      <apex:column headerValue="first Name">
          <apex:inputfield value="{!con.FirstName}"/>
      </apex:column>    
      <apex:column headerValue="Last Name">
          <apex:inputfield value="{!con.LastName}"/>
      </apex:column>     
  </apex:pageblocktable>
  
</apex:pageBlock>  
</apex:form>    
</apex:page>

 

*****controller******
 

public class deleteRowsExample {

public List<Contact> allContactList = new List<Contact>();
public List<Contact> deleteContactList = new List<Contact>();
    
public Account accountRec {get;set;}

//Called when the page loads initially from the "action" method on the apex:page. Populates the Account record and the releated contact list
public void onloadmethod(){

     String aid = System.currentPageReference().getParameters().get('id');
     accountRec = [Select Id,OwnerId,Name,Type,Phone,Website from Account where Id=:aid]; 
     allContactList = [Select Id,FirstName,LastName from Contact where AccountId=:accountRec.Id];
}
//Send the list of contacts to the visualforce page
public List<Contact> getContacts(){
    return allContactList;
}

//Add a temporary contact to the table. Not saved to the database
public void addContact(){
    Contact c = new Contact();
    allContactList.add(c);
}

//Remove a contact from the table.
public void removeContact(){
    Integer indexVal = Integer.valueof(system.currentpagereference().getparameters().get('index'));
    //If the contact is an existing contact then add it to the list to delete from the database
    if(allContactList[indexVal - 1].Id != null)
        deleteContactList.add(allContactList[indexVal - 1]);
    //Remove the contact from the table    
    allContactList.remove(indexVal - 1);            
}    
public void saveChanges(){
    for(Integer i=0; i<allContactList.size(); i++) {
			upsert allContactList; //insert allContactList;
		} 

    //delete the contacts that were removed
    if(deleteContactList.size() > 0){
        delete deleteContactList;
    }
}    
    
}

 

*****Test Class*****
 

@isTest
private class testdeleteRowsExample_Test {
  @isTest static void agregacuentas(){
   Test.startTest();   
 Account acc = new Account();
        acc.Name = 'TestCuenta';
        insert(acc);   
           
        Contact con = new Contact();
        con.AccountId = acc.Id;
        con.FirstName = 'Pedro';
        con.LastName = 'Lopez';
        con.MailingPostalCode = '45546';
        insert (con);
        
        Contact con2 = new Contact();
        con2.AccountId = acc.Id;
        con2.FirstName = 'Rosa';
        con2.LastName = 'Croy';
        con.MailingPostalCode = '66546';
        insert (con2); 
 
deleteRowsExample Rows = new deleteRowsExample();
            Rows.addContact();
            Rows.onloadmethod(); 
            Rows.getContacts();
            Rows.saveChanges();
            Rows.removeContact();
Test.stopTest();
    }
}