<?php

$obrigatorios = ["order", "preco", "comprador"];

$simular_get = ["order" => 13, "preco" => 12060, "comprador" => "Fulano"];

if (!array_diff($obrigatorios, array_keys($simular_get))) {
    echo "True #1".PHP_EOL;
    var_export( $simular_get );
} else {
    echo "Error #1";
}

echo PHP_EOL . PHP_EOL;

$simular_get = ["order" => 13, "bar" => "foo", "preco" => 12060, "comprador" => "Fulano"];

if (!array_diff($obrigatorios, array_keys($simular_get))) {
    echo "True #2".PHP_EOL;
    var_export( $simular_get );
} else {
    echo "Error #2";
}

echo PHP_EOL . PHP_EOL;
echo PHP_EOL . PHP_EOL;

$simular_get = ["order" => 13, "preco" => 12060, "comprador" => "Fulano"];

if (!array_diff_assoc($obrigatorios, array_keys($simular_get))) {
    echo "True #3".PHP_EOL;
    var_export( $simular_get );
} else {
    echo "Error #3";
}

echo PHP_EOL . PHP_EOL;

$simular_get = ["order" => 13, "preco" => 12060, "bar" => "foo", "comprador" => "Fulano"];

if (!array_diff_assoc($obrigatorios, array_keys($simular_get))) {
    echo "True #4".PHP_EOL;
    var_export( $simular_get );
} else {
    echo "Error #4";
}