import java.util.ConcurrentModificationException;
import java.util.Iterator;
import org.junit.Ignore;

/**
 * A generic JUnit test which tests {@code remove} operations on a collection. Can't be invoked
 * directly; please see {@link com.google.common.collect.testing.CollectionTestSuiteBuilder}.
 *
 * @author George van den Driessche
 */
@GwtCompatible

import java.util.Map;
import junit.framework.AssertionFailedError;
import org.junit.Ignore;

/**
 * A generic JUnit test which tests {@link Map#computeIfAbsent}. Can't be invoked directly; please
 * see {@link com.google.common.collect.testing.MapTestSuiteBuilder}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible

import com.google.common.collect.testing.features.MapFeature;
import java.util.Map;
import org.junit.Ignore;

/**
 * A generic JUnit test which tests {@link Map#replace(Object, Object, Object)}. Can't be invoked
 * directly; please see {@link com.google.common.collect.testing.MapTestSuiteBuilder}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible

import java.lang.reflect.Method;
import java.util.List;
import org.junit.Ignore;

/**
 * A generic JUnit test which tests {@code add(Object)} operations on a list. Can't be invoked
 * directly; please see {@link com.google.common.collect.testing.ListTestSuiteBuilder}.
 *
 * @author Chris Povirk
 */
@GwtCompatible

import java.util.ConcurrentModificationException;
import java.util.Iterator;
import java.util.Map.Entry;
import org.junit.Ignore;

/**
 * A generic JUnit test which tests {@code clear()} operations on a map. Can't be invoked directly;
 * please see {@link com.google.common.collect.testing.MapTestSuiteBuilder}.
 *
 * @author George van den Driessche
 * @author Chris Povirk
 */
@GwtCompatible

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import org.junit.Ignore;

/**
 * A generic JUnit test which tests {@link Map#forEach}. Can't be invoked directly; please see
 * {@link com.google.common.collect.testing.MapTestSuiteBuilder}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible

import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import org.junit.Ignore;

/**
 * A generic JUnit test which tests {@code toString()} operations on a map. Can't be invoked
 * directly; please see {@link com.google.common.collect.testing.MapTestSuiteBuilder}.
 *
 * @author Kevin Bourrillion
 * @author Louis Wasserman
 */
@GwtCompatible

import com.google.common.collect.testing.features.MapFeature;
import java.util.Map;
import java.util.Map.Entry;
import org.junit.Ignore;

/**
 * A generic JUnit test which tests {@link Map#putIfAbsent}. Can't be invoked directly; please see
 * {@link com.google.common.collect.testing.MapTestSuiteBuilder}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible

	DB.AutoMigrate(&Product{})

	p := Product{Code: "unique_code", Price: 100}
	DB.Save(&p)

	if !reflect.DeepEqual(p.GetCallTimes(), []int64{1, 1, 0, 1, 1, 0, 0, 0, 0}) {
		t.Fatalf("Callbacks should be invoked successfully, %v", p.GetCallTimes())
	}

	DB.Where("Code = ?", "unique_code").First(&p)
	if !reflect.DeepEqual(p.GetCallTimes(), []int64{1, 1, 0, 1, 0, 0, 0, 0, 1}) {

## O aplicativo **FastAPI** normal

Vamos primeiro ver como o aplicativo da API normal se pareceria antes de adicionar o callback.

Ele terá uma *operação de rota* que receberá um corpo `Invoice`, e um parâmetro de consulta `callback_url` que conterá a URL para o callback.

Essa parte é bastante normal, a maior parte do código provavelmente já é familiar para você: