ARE YOU NOT USING TDD?! – PART 2 (Legacy code)
Last updated Feb 15, 2026
Published May 23, 2015
The content here is under the Attribution 4.0 International (CC BY 4.0) license
In the part one, I introduced the life cycle of TDD. You can see it here and how it works. But often, people come to me and ask about legacy code: how can we start using TDD with legacy code? Should we start from zero? Should we use baby steps? I decided to share my experience in how I used TDD in legacy code and how I got this task done. Also, I have to say many thanks to my friend Alexandre Cintra, who helped me a lot by giving me great tips.
Legacy code is the nightmare of everyone
It doesn’t matter if you are in a big company or a small one. It is normal to have legacy code, and you will need to maintain and even make some improvements as the requests from our clients come. How can I identify legacy code that is impossible to test?
-
Many responsibilities: Usually, legacy code has many lines between 1000 and 2000 (I’ve seen many with 3000) and does everything in one file: database connection, data persistence, business logic, and IO are a couple of examples.
-
Without code pattern: A “great” feature of legacy code is the lack of pattern in its code. When you touch the code base, you usually see huge files and also blank files. I was just playing around in a company repository, and I saw a model without a single line, just with its declaration. Therefore, in the controller was everything else: the data access, DAO, and even the queries were written in the controller.
<?php
class MyLegacyClass {
// omitted code with 50 lines also construct method and some properties was took off
public function setXml($xml) {
try {
$this->xml = $xml;
return $this;
} catch(Exception $e) {
exit($e->getMessage());
}
}
public function getXml() {
//omitted code
return $this->xml;
}
// omitted code with 1k lines
}
See here the entire snippet (hidden for better readability)
<?php
class MyLegacyClass {
// omitted code with 50 lines also construct method and some properties was took off
public function setXml($xml) {
try {
$this->xml = $xml;
return $this;
} catch(Exception $e) {
exit($e->getMessage());
}
}
public function getXml() {
return $this->xml;
}
public function getModalRodoviario() {
try {
$xml = $this->getXml();
return $xml->rodo;
} catch(Exception $e) {
exit($e->getMessage());
}
}
public function printXML() {
$xml = $this->getXml();
print($xml->asXML());
exit;
}
public function setIdeValues($config, $Cte) {
$xml = $this->getXml();
$ide = $xml->infCte->addChild('ide');
$confIde = $config;
$camposObrigatoriosConfIde = array(
//omitted code 31 lines
);
$confToma = $confIde['toma'];
if($confToma == '4') {
$confToma4 = $confIde['toma4'];
unset($confIde['toma4']);
}
unset($confIde['toma']);
$confIde['cUF'] = $this->estadosIBGE[$confIde['cUF']];
$this->chaveAcesso = $this->calculaChaveAcesso(
$confIde['cUF'],
substr(str_replace('-', '', $confIde['dhEmi']),2,4),
$Cte['Empresa']['Entidade']['ent_cnpj'],
$confIde['mod'],
$confIde['serie'],
$confIde['nCT'],
$confIde['tpEmis'],
$confIde['cCT']
);
$Cte->cte_chave = $this->chaveAcesso;
$Cte->save();
$confIde['cDV'] = $this->digVer;
$xml->infCte->addAttribute('Id', 'CTe' . $this->chaveAcesso);
foreach($confIde as $node => $nodeValue) {
if($nodeValue != "" && !is_array($nodeValue)) {
$ide->addChild($node, $nodeValue);
} else {
if(array_key_exists($node, $camposObrigatoriosConfIde))
throw new Exception($camposObrigatoriosConfIde[$node]);
}
}
// exit;
if(isset($confToma4)) {
$toma4 = $ide->addChild('toma4');
$toma4->addChild('toma', $confToma);
$camposObrigatoriosTomador = array(
//omitted code 9 lines
);
$confToma4['toma_data_ent_cont'] = date('Y-m-d H:i:s');
$confToma4['toma_justificativa_cont'] = "Justificativa teste";
foreach($camposObrigatoriosTomador as $campo => $mensagemErro) {
if($confToma4[$campo] == "")
throw new Exception($mensagemErro);
}
$dePara = array(
'fone' => 'toma_telefone',
'xLgr' => 'toma_end_logradouro',
'nro' => 'toma_end_nro',
'xCpl' => 'toma_end_cpl',
'xBairro' => 'toma_end_bairo',
'cMun' => 'toma_end_cod_mun',
'xMun' => 'toma_end_mun',
'UF' => 'toma_end_uf_sigla',
//'CEP' => 'toma_end_cep',
'cPais' => 'toma_cod_end_pais',
'xPais' => 'toma_end_pais',
'email' => 'toma_cont_email',
//'xJust' => 'toma_justificativa_cont'
);
if(strlen($confToma4['toma_cpf_cnpj']) == 11) {
$toma4->addChild('CPF', $confToma4['toma_cpf_cnpj']);
if($confToma4['toma_nome']!="")
$toma4->addChild('xNome', $confToma4['toma_nome']);
} else {
$toma4->addChild('CNPJ', $confToma4['toma_cpf_cnpj']);
if($confToma4['toma_fantasia']!="")
$toma4->addChild('xFant', $confToma4['toma_fantasia']);
if($confToma4['toma_ie']!="")
$toma4->addChild('IE', $confToma4['toma_ie']);
}
if(!empty($confToma4['toma_telefone']))
$toma4->addChild('fone', $confToma4['toma_telefone']);
$enderToma = $toma4->addChild('enderToma');
foreach($dePara as $de => $para) {
$confToma4[$para] = $this->cleaner($confToma4[$para]);
if($confToma4[$para]!="")
$enderToma->addChild($de, $confToma4[$para]);
}
/*if(!empty($confToma4['toma_data_ent_cont']))
$enderToma->addChild('dhCont', implode('T', explode(' ', $confToma4['toma_data_ent_cont'])));*/
} else {
$toma03 = $ide->addChild('toma03');
$toma03->addChild('toma', $confToma);
}
$this->setXml($xml);
}
public function setCompl($config) {
// if($this->validaInputacao($config)) {
$xml = $this->getXml();
$compl = $xml->infCte->addChild('compl');
$confComplPrimeiroBloco = array(
'xCaracAd',
'xCaracSer',
'xEmi'
);
foreach($confComplPrimeiroBloco as $node) {
$config[$node] = $this->cleaner($config[$node]);
if($config[$node]!="")
$compl->addChild($node, $config[$node]);
}
if($config['fluxo']['xOrig'] != "" || $config['fluxo']['pass'] != "") {
$fluxo = $compl->addChild('fluxo');
}
if(!empty($config['fluxo']['xOrig'])) {
$fluxo->addChild('xOrig', $config['fluxo']['xOrig']);
}
if($config['fluxo']['pass'] != "" && count($config['fluxo']['pass']) > 0) {
foreach($config['fluxo']['pass'] as $pass) {
$xpass = $fluxo->addChild('pass');
$nodesPass = array(
'xPass' => 'cdp_sigla_aeroporto_passagem',
'xDest' => 'cdp_sigla_aeroporto_destino',
'xRota' => 'cdp_codigo_rota_entrega'
);
foreach($nodesPass as $nodePass => $nodePassIndex) {
$pass[$nodePassIndex] = $this->cleaner($pass[$nodePassIndex]);
if($pass[$nodePassIndex]!="")
$xpass->addChild($nodePass, $pass[$nodePassIndex]);
}
}
}
if(count($config['Entrega'])) {
$Entrega = $compl->addChild('Entrega');
$config['Entrega']['tpPer'] = $this->cleaner($config['Entrega']['tpPer']);
if($config['Entrega']['tpPer']=="")
switch($config['Entrega']['tpPer']) {
case '0' :
$semData = $Entrega->addChild('semData');
$semData->addChild('tpPer', $config['Entrega']['tpPer']);
break;
case '1' :
case '2' :
case '3' :
$comData = $Entrega->addChild('comData');
$comData->addChild('tpPer', $config['Entrega']['tpPer']);
$config['Entrega']['dProg'] = $this->cleaner($config['Entrega']['dProg']);
if($config['Entrega']['dProg']!="")
$comData->addChild('tpPer', $config['Entrega']['dProg']);
break;
case '4' :
$noPeriodo = $Entrega->addChild('noPeriodo');
$noPeriodo->addChild('tpPer', $config['Entrega']['tpPer']);
$config['Entrega']['dtIni'] = $this->cleaner($config['Entrega']['dtIni']);
if($config['Entrega']['dtIni']!="")
$noPeriodo->addChild('dtIni', $config['Entrega']['dtIni']);
$config['Entrega']['dtFim'] = $this->cleaner($config['Entrega']['dtFim']);
if($config['Entrega']['dtFim']!="")
$noPeriodo->addChild('dtFim', $config['Entrega']['dtFim']);
break;
}
$config['Entrega']['tpHor'] = $this->cleaner($config['Entrega']['tpHor']);
switch($config['Entrega']['tpHor']) {
case '0' :
$semHora = $Entrega->addChild('semHora');
$semHora->addChild('tpHor', $config['Entrega']['tpHor']);
break;
case '1' :
case '2' :
case '3' :
$comHora = $Entrega->addChild('comHora');
$comHora->addChild('tpHor', $config['Entrega']['tpHor']);
$config['Entrega']['hProg'] = $this->cleaner($config['Entrega']['hProg']);
if($config['Entrega']['hProg']!="")
$comHora->addChild('tpHor', $config['Entrega']['hProg']);
break;
case '4' :
$noInter = $Entrega->addChild('noInter');
$noInter->addChild('tpHor', $config['Entrega']['tpHor']);
$config['Entrega']['hIni'] = $this->cleaner($config['Entrega']['hIni']);
if($config['Entrega']['hIni']!="")
$noInter->addChild('hIni', $config['Entrega']['hIni']);
$config['Entrega']['hFim'] = $this->cleaner($config['Entrega']['hFim']);
if($config['Entrega']['hFim']!="")
$noInter->addChild('hFim', $config['Entrega']['hFim']);
break;
}
}
if ( !empty($config['xObs']) ){
$compl->addChild('xObs', $config['xObs']);
}
if(isset($config['ObsCont']) && count($config['ObsCont']) > 0) {
foreach($config['ObsCont'] as $ObsCont) {
$xObsCont = $compl->addChild('ObsCont');
$ObsCont['coic_identificador'] = $this->cleaner($ObsCont['coic_identificador']);
if($ObsCont['coic_identificador']!="")
$xObsCont->addChild('xCampo', $ObsCont['coic_identificador']);
$ObsCont['coic_obs'] = $this->cleaner($ObsCont['coic_obs']);
if($ObsCont['coic_obs']!="")
$xObsCont->addChild('xTexto', $ObsCont['coic_obs']);
}
}
if(isset($config['ObsFisco']) && count($config['ObsFisco']) > 0) {
foreach($config['ObsFisco'] as $ObsFisco) {
$xObsFisco = $compl->addChild('ObsFisco');
$ObsFisco['coif_identificador'] = $this->cleaner($ObsFisco['coif_identificador']);
if($ObsFisco['coif_identificador']!="")
$xObsFisco->addChild('xCampo', $ObsFisco['coif_identificador']);
$ObsFisco['coif_obs'] = $this->cleaner($ObsFisco['coif_obs']);
if($ObsFisco['coif_obs']!="")
$xObsFisco->addChild('xTexto', $ObsFisco['coif_obs']);
}
}
$this->setXml($xml);
// }
}
public function setEmitValues($config) {
$xml = $this->getXml();
$emitDePara = array(
'CNPJ' => 'CNPJ',
'IE' => 'IE',
'xNome' => 'nome_razao',
'xFant' => 'fantasia'
);
$camposObrigatorios = array(
//omitted code 3 lines
);
$emit = $xml->infCte->addChild('emit');
foreach($emitDePara as $node => $nodeValue) {
$config[$nodeValue] = $this->cleaner($config[$nodeValue]);
if($config[$nodeValue]!="") {
$emit->addChild($node, $config[$nodeValue]);
} else {
if(array_key_exists($node, $camposObrigatorios)) {
throw new Exception($camposObrigatorios[$node]);
}
}
}
$emitEnderDePara = array(
'xLgr' => 'logradouro',
'nro' => 'numero',
'xCpl' => 'complemento',
'xBairro' => 'bairro',
'cMun' => 'cod_municipio',
'xMun' => 'municipio',
'UF' => 'UF',
'fone' => 'fone'
);
$camposObrigatoriosEnder = array(
//omitted code 7 lines
);
$enderEmit = $emit->addChild('enderEmit');
foreach($emitEnderDePara as $node => $nodeValue) {
$config[$nodeValue] = $this->cleaner($config[$nodeValue]);
if($config[$nodeValue]!="") {
$enderEmit->addChild($node, $config[$nodeValue]);
} else {
if(array_key_exists($node, $camposObrigatoriosEnder)) {
throw new Exception($camposObrigatoriosEnder[$node]);
}
}
}
$this->setXml($xml);
}
public function setRemValues($config) {
$config = $this->limpaEspacos($config);
$xml = $this->getXml();
$rem = $xml->infCte->addChild('rem');
if(strlen($config['cpfcnpj']) == 14) {
$rem->addChild('CNPJ', str_pad($config['cpfcnpj'], 14, '0', STR_PAD_LEFT));
} else {
$rem->addChild('CPF', str_pad($config['cpfcnpj'], 11, '0', STR_PAD_LEFT));
}
if ( !is_numeric($config['IE']) ) {
$rem->addChild('IE', '000000000');
} else {
$rem->addChild('IE', str_pad($config['IE'], 9, STR_PAD_LEFT));
}
if ( TIPO_AMBIENTE_CTE == 2 ) {
$config['nome'] = 'CT-E EMITIDO EM AMBIENTE DE HOMOLOGACAO - SEM VALOR FISCAL';
$config['xFant'] = 'CT-E EMITIDO EM AMBIENTE DE HOMOLOGACAO - SEM VALOR FISCAL';
}
$rem->addChild('xNome',$config['nome']);
$rem->addChild('xFant', $config['nome']);
if (!empty($config['fone'])){
$rem->addChild('fone', $config['fone']);
}
$enderReme = $rem->addChild('enderReme');
$enderReme->addChild('xLgr', $config['logradouro']);
$enderReme->addChild('nro', $config['numero']);
$enderReme->addChild('xCpl', $config['bairro']);
$enderReme->addChild('xBairro', $config['bairro']);
$enderReme->addChild('cMun', $config['cod_municipio']);
$enderReme->addChild('xMun', $config['municipio']);
if ( !empty($config['CEP']) ) {
$enderReme->addChild('CEP', str_pad($config['CEP'], 8, STR_PAD_LEFT));
}
$enderReme->addChild('UF', $config['UF']);
$enderReme->addChild('cPais', $config['cod_pais']);
$enderReme->addChild('xPais', $config['pais']);
if ( !empty($config['email']) ) {
$rem->addChild('email', $config['email']);
}
$this->setXml($xml);
}
public function setDestValues($config) {
$xml = $this->getXml();
$dest = $xml->infCte->addChild('dest');
if(strlen($config['cpfcnpj']) == 14) {
$dest->addChild('CNPJ', $config['cpfcnpj']);
} else {
$dest->addChild('CPF', $config['cpfcnpj']);
}
if ( !is_numeric($config['IE']) ) {
$dest->addChild('IE', '000000000');
} else {
$dest->addChild('IE', str_pad($config['IE'], 9, STR_PAD_LEFT));
}
if ( TIPO_AMBIENTE_CTE == 2 ) {
$config['nome'] = 'CT-E EMITIDO EM AMBIENTE DE HOMOLOGACAO - SEM VALOR FISCAL';
}
$dest->addChild('xNome', $config['nome']);
if( !empty($config['fone']) ) {
$dest->addChild('fone', $config['fone']);
}
$enderDest = $dest->addChild('enderDest');
$enderDest->addChild('xLgr', $config['logradouro']);
$enderDest->addChild('nro', str_pad($config['numero'], 3, STR_PAD_LEFT));
if( !empty($config['complemento']) ) {
$enderDest->addChild('xCpl', $config['complemento']);
}
$enderDest->addChild('xBairro', $config['bairro']);
$enderDest->addChild('cMun', $config['cod_municipio']);
$enderDest->addChild('xMun', $config['municipio']);
if( !empty($config['CEP']) ) {
$enderDest->addChild('CEP', str_pad($this->cleaner($config['CEP']), 8, '0', STR_PAD_LEFT));
}
$enderDest->addChild('UF', $config['UF']);
if( !empty($config['cod_pais']) ) {
$enderDest->addChild('cPais', $config['cod_pais']);
}
if( !empty($config['pais']) ) {
$enderDest->addChild('xPais', $config['pais']);
}
if( !empty($config['email']) ) {
$dest->addChild('email', $config['email']);
}
$this->setXml($xml);
}
public function setRecValues($config) {
$xml = $this->getXml();
$rec = $xml->infCte->addChild('receb');
if(strlen($config['cpfcnpj']) == 14) {
$rec->addChild('CNPJ', $config['cpfcnpj']);
} else {
$rec->addChild('CPF', $config['cpfcnpj']);
}
if ( !is_numeric($config['IE']) ) {
$rec->addChild('IE', '000000000');
} else {
$rec->addChild('IE', str_pad($config['IE'], 9, STR_PAD_LEFT));
}
if ( TIPO_AMBIENTE_CTE == 2 ) {
$config['nome'] = 'CT-E EMITIDO EM AMBIENTE DE HOMOLOGACAO - SEM VALOR FISCAL';
}
$rec->addChild('xNome', $config['nome']);
if( !empty($config['fone']) ) {
$rec->addChild('fone', $config['fone']);
}
$enderRec = $rec->addChild('enderReceb');
$enderRec->addChild('xLgr', $config['logradouro']);
$enderRec->addChild('nro', str_pad($config['numero'], 3, STR_PAD_LEFT));
if( !empty($config['complemento']) ) {
$enderRec->addChild('xCpl', $config['complemento']);
}
$enderRec->addChild('xBairro', $config['bairro']);
$enderRec->addChild('cMun', $config['cod_municipio']);
$enderRec->addChild('xMun', $config['municipio']);
if( !empty($config['CEP']) ) {
$enderRec->addChild('CEP', $config['CEP']);
}
$enderRec->addChild('UF', $config['UF']);
if( !empty($config['cod_pais']) ){
$enderRec->addChild('cPais', $config['cod_pais']);
}
if( empty($config['pais']) ) {
$enderRec->addChild('xPais', $config['pais']);
}
if( !empty($config['email']) ) {
$rec->addChild('email', $config['email']);
}
$this->setXml($xml);
}
public function setExpValues($config) {
$xml = $this->getXml();
$exp = $xml->infCte->addChild('exped');
if(strlen($config['cpfcnpj']) == 14) {
$exp->addChild('CNPJ', $config['cpfcnpj']);
} else {
$exp->addChild('CPF', $config['cpfcnpj']);
}
if ( !is_numeric($config['IE']) ) {
$exp->addChild('IE', '000000000');
} else {
$exp->addChild('IE', str_pad($config['IE'], 9, STR_PAD_LEFT));
}
if ( TIPO_AMBIENTE_CTE == 2 ) {
$config['nome'] = 'CT-E EMITIDO EM AMBIENTE DE HOMOLOGACAO - SEM VALOR FISCAL';
}
$exp->addChild('xNome', $config['nome']);
$config['fone'] = $this->cleaner($config['fone']);
if( !empty($config['fone']) ) {
$exp->addChild('fone', $config['fone']);
}
$enderExp = $exp->addChild('enderExped');
$enderExp->addChild('xLgr', $config['logradouro']);
$enderExp->addChild('nro', str_pad($config['numero'], 3, STR_PAD_LEFT));
if($this->cleaner($config['complemento']))
$enderExp->addChild('xCpl', $config['complemento']);
$enderExp->addChild('xBairro', $config['bairro']);
$enderExp->addChild('cMun', $config['cod_municipio']);
$enderExp->addChild('xMun', $config['municipio']);
if($this->cleaner($config['CEP']))
$enderExp->addChild('CEP', $config['CEP']);
$enderExp->addChild('UF', $config['UF']);
if($this->cleaner($config['cod_pais'])!="")
$enderExp->addChild('cPais', $config['cod_pais']);
if($this->cleaner($config['pais'])!="")
$enderExp->addChild('xPais', $config['pais']);
if( !empty($config['email']) ) {
$exp->addChild('email', $config['email']);
}
$this->setXml($xml);
}
public function setInfCteComp($config) {
$xml = $this->getXml();
if($config['chave']!="") {
$infCteComp = $xml->infCte->addChild('infCteComp');
$infCteComp->addChild('chave', $config['chave']);
}
$this->setXml($xml);
}
public function setInfCteAnu($config) {
$xml = $this->getXml();
if($config['chCte']!="" && $config['dEmi']!="") {
$infCteAnu = $xml->infCte->addChild('infCteAnu');
$infCteAnu->addChild('chCte', $config['chCte']);
$infCteAnu->addChild('dEmi', $config['dEmi']);
}
$this->setXml($xml);
}
public function setAutXML($config) {
$xml = $this->getXml();
foreach($config as $cda) {
$autXML = $xml->infCte->addChild('autXML');
if(strlen($cda['cda_cpf_cnpj_autori']) == 14)
$autXML->addChild('CNPJ', $cda['cda_cpf_cnpj_autori']);
else
$autXML->addChild('CPF', $cda['cda_cpf_cnpj_autori']);
}
$this->setXml($xml);
}
public function setModalRodoviario($config) {
$xml = $this->getXml();
$rodo = $xml->infCte->infCTeNorm->infModal->addChild('rodo');
$modal = $config['rodo'];
$rodo->addChild('RNTRC', $modal['RNTRC']);
$rodo->addChild('dPrev', $modal['dPrev']);
$rodo->addChild('lota', $modal['lota']);
if( !empty($modal['CIOT']) ) {
$rodo->addChild('CIOT', str_pad($this->cleaner($modal['CIOT']), 12, STR_PAD_LEFT));
}
if(isset($modal['occ']) && count($modal['occ']) > 0) {
foreach($modal['occ'] as $occ) {
$xocc = $rodo->addChild('occ');
$xocc->addChild('serie', $occ['occ_serie']);
$xocc->addChild('nOcc', $occ['occ_numero']);
$xocc->addChild('dEmi', $occ['occ_demi']);
$emiOcc = $xocc->addChild('emiOcc');
$emiOcc->addChild('CNPJ', $occ['occ_cnpj']);
if($this->cleaner($occ['occ_cint'])!="")
$emiOcc->addChild('cInt', $occ['occ_cint']);
$emiOcc->addChild('IE', $occ['occ_ie']);
$emiOcc->addChild('UF', $occ['Uf']['uf_sigla']);
if($this->cleaner($occ['occ_fone'])!="")
$emiOcc->addChild('fone', $occ['occ_fone']);
}
}
if(isset($modal['valePed']) && count($modal['valePed']) > 0) {
foreach($modal['valePed'] as $valePed) {
$xValePed = $rodo->addChild('valePed');
$xValePed->addChild('CNPJForn', $valePed['vpd_cnpj_forn']);
$xValePed->addChild('nCompra', $valePed['vpd_ncompra']);
if($this->cleaner($valePed['vpd_cnpj_pg'])!="")
$xValePed->addChild('CNPJPg', $valePed['vpd_cnpj_pg']);
$xValePed->addChild('vValePed', $valePed['vpd_valor_vale_pedagio']);
}
}
if(isset($modal['veic']) && count($modal['veic']) > 0) {
foreach($modal['veic'] as $confVeic){
$veic = $rodo->addChild('veic');
if($this->cleaner($confVeic['CteVeiculo']['cve_cod_interno'])!="")
$veic->addChild('cInt', $confVeic['CteVeiculo']['cve_cod_interno']);
$veic->addChild('RENAVAM', $confVeic['CteVeiculo']['cve_renavam']);
$veic->addChild('placa', str_replace(' ', '', $confVeic['CteVeiculo']['cve_placa'])); // remove qualquer espa\E7o branco
$veic->addChild('tara', $confVeic['CteVeiculo']['cve_tara']);
$veic->addChild('capKG', $confVeic['CteVeiculo']['cve_capacidade_kg']);
$veic->addChild('capM3', $confVeic['CteVeiculo']['cve_capacidade_mc']);
$veic->addChild('tpProp', $confVeic['CteVeiculo']['cve_proprietario']);
$veic->addChild('tpVeic', $confVeic['CteVeiculo']['CteVeiculoTipo']['cvt_codigo']);
$veic->addChild('tpRod', $confVeic['CteVeiculo']['CteVeiculoRodado']['cvr_codigo']);
$veic->addChild('tpCar', $confVeic['CteVeiculo']['CteVeiculoCarroceria']['cvc_codigo']);
$veic->addChild('UF', $confVeic['CteVeiculo']['Uf']['uf_sigla']);
if($confVeic['CteVeiculo']['cve_proprietario'] != 'P') {
$prop = $rodo->addChild('prop');
$infoVeicProp = CteVeiculo::consultaVeiculo($confVeic['CteVeiculo']['cve_id']);
$veicProp = reset($infoVeicProp['CteEmpresaVeiculoProprietarioAtrb']);
$veicPropTipo = $veicProp['CteEmpresaVeiculoProprietarioTipo'];
if($veicProp['evpa_tipo_pessoa'] == 'FIS'){
$prop->addChild('CPF', $veicProp['evpa_cpf_cnpj']);
} else {
$prop->addChild('CNPJ', $veicProp['evpa_cpf_cnpj']);
}
$prop->addChild('RNTRC', $veicProp['evpa_rntrc']);
$prop->addChild('xNome', $veicProp['evpa_nome_razao']);
$prop->addChild('IE', $veicProp['evpa_rg_ie']);
$prop->addChild('UF', $veicProp['Uf']['uf_sigla']);
$prop->addChild('tpProp', $veicPropTipo['evpt_codigo']);
}
}
}
if(isset($modal['lacre']) && count($modal['lacre']) > 0) {
foreach($modal['lacre'] as $infLacre) {
$lacRodo = $rodo->addChild('lacRodo');
$lacRodo->addChild('nLacre', $infLacre['cmrl_num_lacre']);
}
}
if(isset($modal['moto']) && count($modal['moto']) > 0) {
foreach($modal['moto'] as $infMoto) {
$moto = $rodo->addChild('moto');
$moto->addChild('xNome', $infMoto['CteMotorista']['mot_nome']);
$moto->addChild('CPF', $infMoto['CteMotorista']['mot_cpf']);
}
}
$this->setXml($xml);
}
public function setVPrestValues($config) {
$xml = $this->getXml();
$vPrest = $xml->infCte->addChild('vPrest');
$vPrest->addChild('vTPrest', empty($config['vTPrest'])? '0.00' : $config['vTPrest']);
$vPrest->addChild('vRec', empty($config['vRec'])? '0.00' : $config['vRec']);
if(isset($config['Comp']) && count($config['Comp']) > 0) {
// \E8 obrigat\F3rio ter um elemento filho do Comp para emitir a nota
foreach($config['Comp'] as $Comp) {
// \E8 necess\E1rio fazer a verifica\E7\E3o para n\E3o ocorrer erros no xml
if ( !empty($Comp['cic_nome_componente']) && !empty($Comp['cic_valor_componente']) ){
$xComp = $vPrest->addChild('Comp');
// verificar se esse campo \E9 vazio caso contr\E1rio ocorrer\E1 um erro no xml
$xComp->addChild('xNome', (empty($Comp['cic_nome_componente']))? 'ND' : $Comp['cic_nome_componente']);
$xComp->addChild('vComp', (empty($Comp['cic_valor_componente']))? '00.00' : $Comp['cic_valor_componente']); //13,2 ER25 15 posi\E7\F5es, sendo 13 inteiras e 2 decimais.
}
}
}
$this->setXml($xml);
}
public function setImpValues($config) {
$xml = $this->getXml();
$imp = $xml->infCte->addChild('imp');
$ICMS = $imp->addChild('ICMS');
switch($config['CST']) {
case '00' :
$ICMS00 = $ICMS->addChild('ICMS00');
$ICMS00->addChild('CST', $config['CST']);
$ICMS00->addChild('vBC', $config['vBC']);
$ICMS00->addChild('pICMS', $config['pICMS']);
$ICMS00->addChild('vICMS', $config['vICMS']);
break;
case '20' :
$ICMS20 = $ICMS->addChild('ICMS20');
$ICMS20->addChild('CST', $config['CST']);
$ICMS20->addChild('pRedBC', $config['pRedBC']);
$ICMS20->addChild('vBC', $config['vBC']);
$ICMS20->addChild('pICMS', $config['pICMS']);
$ICMS20->addChild('vICMS', $config['vICMS']);
break;
case '40' :
case '41' :
case '51' :
$ICMS45 = $ICMS->addChild('ICMS45');
$ICMS45->addChild('CST', $config['CST']);
break;
case '60' :
$ICMS60 = $ICMS->addChild('ICMS60');
$ICMS60->addChild('CST', $config['CST']);
$ICMS60->addChild('vBCSTRet', $config['vBCSTRet']);
$ICMS60->addChild('vICMSSTRet', $config['vICMSSTRet']);
$ICMS60->addChild('pICMSSTRet', $config['pICMSSTRet']);
$ICMS60->addChild('vCred', $config['vCred']);
break;
case '90' :
$ICMS90 = $ICMS->addChild('ICMS90');
$ICMS90->addChild('CST', $config['CST']);
$ICMS90->addChild('pRedBC', $config['pRedBC']);
$ICMS90->addChild('vBC', $config['vBC']);
$ICMS90->addChild('pICMS', $config['pICMS']);
$ICMS90->addChild('vICMS', $config['Vicms']);
$ICMS90->addChild('vCred', $config['vCred']);
break;
case 'SN' :
$ICMSSN = $ICMS->addChild('ICMSSN');
$ICMSSN->addChild('indSN', 1);
break;
default: // Default ser\E1 outra UF
$ICMSOutraUF = $ICMS->addChild('ICMSOutraUF');
$ICMSOutraUF->addChild('CST', '90');
$ICMSOutraUF->addChild('pRedBCOutraUF', $config['pRedBCOutraUF']);
$ICMSOutraUF->addChild('vBCOutraUF', $config['vBCOutraUF']);
$ICMSOutraUF->addChild('pICMSOutraUF', $config['pICMSOutraUF']);
$ICMSOutraUF->addChild('vICMSOutraUF', $config['vICMSOutraUF']);
}
if ( !empty($config['vTotTrib']) ) {
$imp->addChild('vTotTrib', $config['vTotTrib']);
}
if ( !empty($config['infAdFisco']) ) {
$imp->addChild('infAdFisco', $config['infAdFisco']);
}
$this->setXml($xml);
}
public function setInfCTeNormValues($config) {
$xml = $this->getXml();
$infCTeNorm = $xml->infCte->addChild('infCTeNorm');
$dInfCarga = $config['infCarga'];
$infCarga = $infCTeNorm->addChild('infCarga');
if( $this->cleaner( $dInfCarga['vCarga']) != '' ){
$infCarga->addChild('vCarga', $dInfCarga['vCarga']);
}
if ( empty($dInfCarga['proPred']) ){
$dInfCarga['proPred'] = 'N/D';
}
$infCarga->addChild('proPred', $dInfCarga['proPred']);
if( $this->cleaner($dInfCarga['xOutCat']) != '') {
$infCarga->addChild('xOutCat', $dInfCarga['xOutCat']);
}
if(count($config['infQ']) > 0) {
foreach($config['infQ'] as $dInfQ) {
$infQ = $infCarga->addChild('infQ');
$infQ->addChild('cUnid', str_pad($dInfQ['cnc_codigo_unidade_medida'], 2, '0', STR_PAD_LEFT)/*'01'*/);
$infQ->addChild('tpMed', $dInfQ['cnc_tipo_medida']/*'PESO BRUTO'*/);
$infQ->addChild('qCarga', $dInfQ['cnc_valor_componente']/*'12345678911.1154'*/);
}
}
$documentos = $config['infDoc'];
if ( isset($documentos) && count($documentos) > 0){
$infDoc = $infCTeNorm->addChild('infDoc');
foreach($documentos as $dInfDoc) {
switch($dInfDoc['cnf_tipo']) {
case 1 :
$infNF = $infDoc->addChild('infNF');
$infNF->addChild('nRoma', str_pad($dInfDoc['cnf_numero_romaneio'], 20, STR_PAD_LEFT)/*'12315646156189189111'*/);
$infNF->addChild('nPed', str_pad($dInfDoc['cnf_numero_pedido'], 20, STR_PAD_LEFT)/*'12315646156189189111'*/);
$infNF->addChild('mod', '01'/*$dInfDoc['cnf_modelo_nota']'04'*/); //Preencher com:01 - NF Modelo 01/1A e Avulsa;04 - NF de Produtor
$infNF->addChild('serie', str_pad($dInfDoc['cnf_serie'], 3, STR_PAD_LEFT)/*'1'*/);
$infNF->addChild('nDoc', str_pad($dInfDoc['cnf_numero'], 20, STR_PAD_LEFT)/*'1'*/);
$infNF->addChild('dEmi', ($dInfDoc['cnf_data_emissao'] == '---')? $dInfDoc['cnf_data_emissao'] : date('Y-m-d')); /
$infNF->addChild('vBC', ($dInfDoc['cnf_valor_base_icms'])? $dInfDoc['cnf_valor_base_icms'] : '0.00'/*'8047.11'*/);
$infNF->addChild('vICMS', ($dInfDoc['cnf_total_icms'])? $dInfDoc['cnf_total_icms'] : '0.00'/*'965.65'*/);
$infNF->addChild('vBCST', ($dInfDoc['cnf_valor_base_icms_st'])? $dInfDoc['cnf_valor_base_icms_st'] : '0.00'/*'123.00'*/);
$infNF->addChild('vST', ($dInfDoc['cnf_valor_icms_st'])? $dInfDoc['cnf_valor_icms_st'] : '0.00'/*'123.00'*/);
$infNF->addChild('vProd', ($dInfDoc['cnf_valor_total_produtos'])? $dInfDoc['cnf_valor_total_produtos'] : '0.00'/*'123.00'*/);
$infNF->addChild('vNF', ($dInfDoc['cnf_valor_total_nf'])? $dInfDoc['cnf_valor_total_nf'] : '0.00'/*'123.00'*/);
$infNF->addChild('nCFOP', ($dInfDoc['cnf_cfop_prodominante'])? $dInfDoc['cnf_cfop_prodominante'] : '5353'/*'5353'*/);
if ( !empty($dInfDoc['cnf_peso_total']) ){
$infNF->addChild('nPeso', $dInfDoc['cnf_peso_total']);
}
if ( !empty($dInfDoc['cnf_suframa']) ) {
$infNF->addChild('PIN', str_pad($dInfDoc['cnf_suframa'], 9, STR_PAD_LEFT/*'123'*/));
}
if ( !empty($dInfDoc['cnf_data_prevista_entrega']) && $dInfDoc['cnf_data_prevista_entrega'] != '---' ) {
$infNF->addChild('dPrev', $dInfDoc['cnf_data_prevista_entrega']);
}
break;
case 2 :
$infNFe = $infDoc->addChild('infNFe');
$infNFe->addChild('chave', $dInfDoc['cnf_eletronica_chave_acesso']);
if ( !empty($dInfDoc['cnf_eletronica_suframa']) ){
$infNFe->addChild('PIN', str_pad($dInfDoc['cnf_eletronica_suframa'], 9, STR_PAD_LEFT));
}
if ( !empty($dInfDoc['cnf_eletronica_data_prevista']) && $dInfDoc['cnf_eletronica_data_prevista'] != '---' ){
$infNFe->addChild('dPrev', $dInfDoc['cnf_eletronica_data_prevista']);
}
$unidadeTransporteNFe = $dInfDoc['CteInfNotaFiscalUnidadeTransporte'];
if(count($unidadeTransporteNFe) > 0) {
foreach($unidadeTransporteNFe as $dInfUnidTranspNFe) {
$infUnidTranspNFe = $infNFe->addChild('infUnidTransp');
$infUnidTranspNFe->addChild('tpUnidTransp', $dInfUnidTranspNFe['cut_tipo_unidade_transportadora']);
$infUnidTranspNFe->addChild('idUnidTransp', $dInfUnidTranspNFe['cut_identificacao_unidade_transportadora']);
$lacresUnidTranspNFe = $dInfUnidTranspNFe['CteInfNotaFiscalUnidadeTransporteLacre'];
if(count($lacresUnidTranspNFe) > 0) {
foreach($lacresUnidTranspNFe as $dLacUnidTranspNFe) {
$lacUnidTranspNFe = $infUnidTranspNFe->addChild('lacUnidTransp');
$lacUnidTranspNFe->addChild('nLacre', $dLacUnidTranspNFe['ctl_numero_lacre']);
}
}
$unidadesDeCargaTransNFe = $dInfUnidTranspNFe['CteInfNotaFiscalUnidadeCarga'];
if(count($unidadesDeCargaTransNFe) > 0) {
foreach($unidadesDeCargaTransNFe as $dInfUnidCargaTranspNFe) {
$infUnidCargaTranspNFe = $infUnidTranspNFe->addChild('infUnidCarga');
$infUnidCargaTranspNFe->addChild('tpUnidCarga', $dInfUnidCargaTranspNFe['cuc_tipo_unidade_carga']);
$infUnidCargaTranspNFe->addChild('idUnidCarga', $dInfUnidCargaTranspNFe['cuc_identificacao_unidade_carga']);
$lacresUnidCargaTranspNFe = $dInfUnidCargaTranspNFe['CteInfNotaFiscalUnidadeCargaLacre'];
if(count($lacresUnidCargaTranspNFe) > 0) {
foreach($lacresUnidCargaTranspNFe as $dLacUnidCargaTranspNFe) {
$lacUnidCargaTranspNFe = $infUnidCargaTranspNFe->addChild('lacUnidCarga');
$lacUnidCargaTranspNFe->addChild('nLacre', $dLacUnidCargaTranspNFe['ccl_numero_lacre']);
}
}
$infUnidCargaTranspNFe->addChild('qtdRat', $dInfUnidCargaTranspNFe['cuc_qtd_rateado']);
}
}
}
}
break;
}
foreach($config['seg'] as $dSeg) {
$seg = $infCTeNorm->addChild('seg');
$seg->addChild('respSeg', $dSeg['cns_responsavel_seguro']/*'4'*/);
if($this->cleaner($dSeg['cns_nome_seguradora'])!="") {
$seg->addChild('xSeg', $dSeg['cns_nome_seguradora']/*'Zurich'*/);
}
if($this->cleaner($dSeg['cns_numero_apolice'])!="") {
$seg->addChild('nApol', $dSeg['cns_numero_apolice']);
}
if($this->cleaner($dSeg['cns_numero_averbacao'])!="") {
$seg->addChild('nAver', str_pad($dSeg['cns_numero_averbacao'], 20, STR_PAD_LEFT));
}
// Padr\E3o da carga \E9 13,2
if($this->cleaner($dSeg['cns_valor_carga_efeito_averbacao'])!="" && $dSeg['cns_valor_carga_efeito_averbacao'] != '000') {
$seg->addChild('vCarga', $dSeg['cns_valor_carga_efeito_averbacao']/*'47000.00'*/);
}
}
$infModal = $infCTeNorm->addChild('xs:infModal', $config['infModal']['xs:any']->asXML());
$infModal->addAttribute('versaoModal', $config['infModal']['versaoModal']);
foreach($config['peri'] as $dPeri) {
$peri = $infCTeNorm->addChild('peri');
$peri->addChild('nONU', $dPeri['cno_numero_onu']);
$peri->addChild('xNomeAE', $dPeri['cno_nome_apropriado_embarque_produto']);
$peri->addChild('xClaRisco', $dPeri['cno_classe_subclasse']);
$peri->addChild('grEmb', $dPeri['cno_grupo_embarque']);
$peri->addChild('qTotProd', $dPeri['cno_quantidade_total_produto']);
$peri->addChild('qVolTipo', $dPeri['cno_quantidade_tipo_volume']);
$peri->addChild('pontoFulgor', $dPeri['cno_ponto_fulgor']);
}
// Se existir carros novos \E9 obrigat\F3rio informar os campos abaixo
if ( count($config['veicNovos']) > 0 ) {
foreach($config['veicNovos'] as $dVeicNovos) {
$veicNovos = $infCTeNorm->addChild('veicNovos');
$veicNovos->addChild('chassi', $dVeicNovos['cvt_chassi_veiculo']);
$veicNovos->addChild('cCor', $dVeicNovos['cvt_cor_veiculo']);
$veicNovos->addChild('xCor', $dVeicNovos['cvt_descricao_cor']);
$veicNovos->addChild('cMod', $dVeicNovos['cvt_codigo_marca_modelo']);
$veicNovos->addChild('vUnit', $dVeicNovos['cvt_valor_unitario_veiculo']);
$veicNovos->addChild('vFrete', $dVeicNovos['cvt_frete_unitario']);
}
}
$this->setXml($xml);
}
public function save($cte_id) {
try {
$xml = $this->getXml();
$cteXml = CteXmlTable::getInstance()->findOneByCteId($cte_id);
if(!$cteXml instanceof CteXml)
$cteXml = new CteXml();
$cteXml->ctx_xml = $xml;
$cteXml->cte_id = $cte_id;
$cteXml->ctx_qem = 1;
$cteXml->save();
return $this;
} catch(Exception $e) {
exit($e->getMessage());
}
}
private function limpaEspacos($arranjo) {
foreach($arranjo as $indice => $valor) {
if(!is_array($valor)) {
$arranjo[$indice] = trim($valor);
}
}
return $arranjo;
}
private function cleaner($str) {
$str = trim($str);
return $str;
}
public function calculaDv($cCT) {
// omitted code with 11 lines
}
public function calculaChaveAcesso($cUF, $AAMM, $CNPJ, $mod, $serie, $nCT, $tpEmis, $cCT) {
// omitted code with 20 lines
}
}
}
}
Establishing a Safety Net
Before you begin the refactoring cycle above, there’s a critical prerequisite: create a characterization test (also called a golden master test or approval test) that captures the current behavior of your legacy code as a baseline.
Why is this important? Legacy code often lacks unit tests, making it risky to refactor. Without a safety net, you might inadvertently change the system’s behavior during refactoring—and you won’t know until your users complain. Characterization tests solve this problem.
How it works:
A characterization test captures the actual output (or behavior) of your legacy code at a specific moment. For example, you might:
- Call the legacy method with a known input
- Capture the output (could be XML, JSON, database state, or anything else)
- Store this output as your “golden master” or baseline
Subsequent refactorings can then be validated against this baseline. If any behavior changes, the test fails immediately, alerting you to the problem.
// Example: Approval test for MyLegacyClass
public function test_setCompl_produces_expected_output() {
$legacyClass = new MyLegacyClass();
$legacyClass->setXml($this->sampleXml);
$config = [/* ... */];
$legacyClass->setCompl($config);
$output = $legacyClass->getXml()->asXML();
// Approve the current output as the baseline
$this->assertApprovalEquals($output, 'compl_output.approved.xml');
}
For a detailed exploration of characterization tests, golden master testing, and refactoring techniques, see Characterization Tests: A Hands-On Experience. This post provides deeper insights into implementing these tests and how they complement your TDD approach.
Then proceed with the refactoring cycle. Now that you have approval tests confirming the baseline behavior, you can safely proceed with extracting classes and refactoring with confidence. Each refactoring step should keep the approval tests passing, ensuring you never accidentally change what the system does—only how it does it.
Crying, Thinking and Planning
As you can see now we have a class with 1054 lines and our challenge is to transform it into testable code. As a first step, I’d recommend you to cry and as a second step, we can start to think about what the code does and how can we break it down in pieces.
In our code we have a couple of methods that can be separated into classes instead of methods because they have their behavior for example the method setCompl($config) will add to our XML a bunch of nodes depending on some conditions in this case is used a switch statement either a couple of if’s.
class Compl {
public function setCompl($config) {
$xml = $this->getXml();
$compl = $xml->infCte->addChild('compl');
$confComplPrimeiroBloco = array(
'xCaracAd',
'xCaracSer',
'xEmi'
);
foreach($confComplPrimeiroBloco as $node) {
// omitted code
}
// omitted code
}
}
See here the entire snippet (hidden for better readability)
class Compl {
public function setCompl($config) {
$xml = $this->getXml();
$compl = $xml->infCte->addChild('compl');
$confComplPrimeiroBloco = array(
'xCaracAd',
'xCaracSer',
'xEmi'
);
foreach($confComplPrimeiroBloco as $node) {
$config[$node] = $this->cleaner($config[$node]);
if($config[$node]!="")
$compl->addChild($node, $config[$node]);
}
if($config['fluxo']['xOrig'] != "" || $config['fluxo']['pass'] != "") {
$fluxo = $compl->addChild('fluxo');
}
if(!empty($config['fluxo']['xOrig'])) {
$fluxo->addChild('xOrig', $config['fluxo']['xOrig']);
}
if($config['fluxo']['pass'] != "" && count($config['fluxo']['pass']) > 0) {
foreach($config['fluxo']['pass'] as $pass) {
$xpass = $fluxo->addChild('pass');
$nodesPass = array(
'xPass' => 'cdp_sigla_aeroporto_passagem',
'xDest' => 'cdp_sigla_aeroporto_destino',
'xRota' => 'cdp_codigo_rota_entrega'
);
foreach($nodesPass as $nodePass => $nodePassIndex) {
$pass[$nodePassIndex] = $this->cleaner($pass[$nodePassIndex]);
if($pass[$nodePassIndex]!="")
$xpass->addChild($nodePass, $pass[$nodePassIndex]);
}
}
}
if(count($config['Entrega'])) {
$Entrega = $compl->addChild('Entrega');
$config['Entrega']['tpPer'] = $this->cleaner($config['Entrega']['tpPer']);
if($config['Entrega']['tpPer']=="")
switch($config['Entrega']['tpPer']) {
case '0' :
$semData = $Entrega->addChild('semData');
$semData->addChild('tpPer', $config['Entrega']['tpPer']);
break;
case '1' :
case '2' :
case '3' :
$comData = $Entrega->addChild('comData');
$comData->addChild('tpPer', $config['Entrega']['tpPer']);
$config['Entrega']['dProg'] = $this->cleaner($config['Entrega']['dProg']);
if($config['Entrega']['dProg']!="")
$comData->addChild('tpPer', $config['Entrega']['dProg']);
break;
case '4' :
$noPeriodo = $Entrega->addChild('noPeriodo');
$noPeriodo->addChild('tpPer', $config['Entrega']['tpPer']);
$config['Entrega']['dtIni'] = $this->cleaner($config['Entrega']['dtIni']);
if($config['Entrega']['dtIni']!="")
$noPeriodo->addChild('dtIni', $config['Entrega']['dtIni']);
$config['Entrega']['dtFim'] = $this->cleaner($config['Entrega']['dtFim']);
if($config['Entrega']['dtFim']!="")
$noPeriodo->addChild('dtFim', $config['Entrega']['dtFim']);
break;
}
$config['Entrega']['tpHor'] = $this->cleaner($config['Entrega']['tpHor']);
switch($config['Entrega']['tpHor']) {
case '0' :
$semHora = $Entrega->addChild('semHora');
$semHora->addChild('tpHor', $config['Entrega']['tpHor']);
break;
case '1' :
case '2' :
case '3' :
$comHora = $Entrega->addChild('comHora');
$comHora->addChild('tpHor', $config['Entrega']['tpHor']);
$config['Entrega']['hProg'] = $this->cleaner($config['Entrega']['hProg']);
if($config['Entrega']['hProg']!="")
$comHora->addChild('tpHor', $config['Entrega']['hProg']);
break;
case '4' :
$noInter = $Entrega->addChild('noInter');
$noInter->addChild('tpHor', $config['Entrega']['tpHor']);
$config['Entrega']['hIni'] = $this->cleaner($config['Entrega']['hIni']);
if($config['Entrega']['hIni']!="")
$noInter->addChild('hIni', $config['Entrega']['hIni']);
$config['Entrega']['hFim'] = $this->cleaner($config['Entrega']['hFim']);
if($config['Entrega']['hFim']!="")
$noInter->addChild('hFim', $config['Entrega']['hFim']);
break;
}
}
if ( !empty($config['xObs']) ){
$compl->addChild('xObs', $config['xObs']);
}
if(isset($config['ObsCont']) && count($config['ObsCont']) > 0) {
foreach($config['ObsCont'] as $ObsCont) {
$xObsCont = $compl->addChild('ObsCont');
$ObsCont['coic_identificador'] = $this->cleaner($ObsCont['coic_identificador']);
if($ObsCont['coic_identificador']!="")
$xObsCont->addChild('xCampo', $ObsCont['coic_identificador']);
$ObsCont['coic_obs'] = $this->cleaner($ObsCont['coic_obs']);
if($ObsCont['coic_obs']!="")
$xObsCont->addChild('xTexto', $ObsCont['coic_obs']);
}
}
if(isset($config['ObsFisco']) && count($config['ObsFisco']) > 0) {
foreach($config['ObsFisco'] as $ObsFisco) {
$xObsFisco = $compl->addChild('ObsFisco');
$ObsFisco['coif_identificador'] = $this->cleaner($ObsFisco['coif_identificador']);
if($ObsFisco['coif_identificador']!="")
$xObsFisco->addChild('xCampo', $ObsFisco['coif_identificador']);
$ObsFisco['coif_obs'] = $this->cleaner($ObsFisco['coif_obs']);
if($ObsFisco['coif_obs']!="")
$xObsFisco->addChild('xTexto', $ObsFisco['coif_obs']);
}
}
$this->setXml($xml);
}
}
Breaking Down Responsibilities
Look at what we just did. The original MyLegacyClass was trying to handle everything—XML manipulation, business logic, validation, and persistence. This violates the Single Responsibility Principle and makes testing nearly impossible.
Our refactoring goal is simple: Extract tightly-coupled functionality into focused, single-purpose classes. In this case, we extracted the Compl class to handle only the complement section of the XML document. This achieves three things:
- Testability - We can now test
Complin isolation without worrying about the entire legacy class - Maintainability - Each class has one reason to change, making the code easier to understand and modify
- Reusability -The
Complclass can be used elsewhere without dragging along unrelated code
It is much better now, isn’t it? We’ve got one class with one responsibility and very compact, just 146 lines. Although this class we have just created could be improved as well, it is a subject for other posts.
So we got what we need to do, and we have a plan already:
- Analyze the methods
- Extract and create new classes
Replace Legacy Code with Clean Code
Now that we have our new, testable Compl class, we need to stop using the old methods from the legacy class. Our goal here is to gradually replace all calls to the bloated methods with our clean, focused classes.
public function setIdeValues($config, $Cte) {
//omitted code
}
public function setCompl($config) {
$newCode = new Compl();
$newCode->setCompl($config);
}
public function setEmitValues($config) {
//omitted code
}
3. Substitute legacy code to your new code
Now we should test our code to see if it’s still working, once we have this confirmation we can now create our unit tests and repeat the cycle. As you start refactoring all the legacy using those steps you’ll start to have your source code with better quality, maintainability and of course testability.
It is Hard, But Worth It
It is not easy to restructure all the legacy code with new code, but the result is worthwhile. You can follow the ideology of baby steps in this refactor as well. As you change the legacy to the new code, you test to see if everything is the same. The trick here is to be patient and change piece by piece. I tried to show one single way of doing it, but on the internet, you can find thousands.
Refactoring legacy code is not easy. You’re working with code that was never designed to be tested, that grew organically (often chaotically), and that may have critical business logic woven throughout. It requires patience, discipline, and incremental progress.
But the results are worth the effort. Each extracted class brings your codebase closer to quality, testability, and maintainability. Follow the “baby steps” ideology: change one method, test the system to ensure nothing broke, then move to the next. This disciplined approach reduces risk and keeps you confident.
The Refactoring Cycle (Recap)
- Create your unit tests
- Extract and create new classes
- Substitute legacy code with your new code
- Make sure everything is working
Key Takeaway
TDD and legacy code are not mutually exclusive. By systematically extracting responsibilities, creating focused classes, and writing tests around them, you can modernize any codebase. The key is patience, baby steps, and clarity about why you’re refactoring, not just how. Each refactoring should bring you closer to code that is testable, maintainable, and a pleasure to work with.
Appendix
Edit: Jun 17, 2015
You can find useful information in my slides below. It was created for my talk at Samsung Ocean
Edit: July 28, 2015
Legacy software systems . . . were developed decades ago and have been continually modified to meet changes in business requirements and computing platforms. The proliferation of such systems is causing headaches for large organizations that find them costly to maintain and risky to evolve - Dayani-Fard
References
- Jones, P. M. (2016). Modernizing Legacy Applications in PHP. Packt Publishing Ltd.
Resources
Changelog
- Nov 30, 2023 - Added “How to use TDD in Legacy Projects - Tech excellence” as a resource