ExamplesIT.java

/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.neo4j.docs.driver;

import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.extension.RegisterExtension;
import org.junit.jupiter.api.parallel.Execution;
import org.junit.jupiter.api.parallel.ExecutionMode;

import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.UUID;

import org.neo4j.driver.Config;
import org.neo4j.driver.Driver;
import org.neo4j.driver.Session;
import org.neo4j.driver.SessionConfig;
import org.neo4j.driver.Value;
import org.neo4j.driver.Values;
import org.neo4j.driver.exceptions.value.Uncoercible;
import org.neo4j.driver.internal.util.EnabledOnNeo4jWith;
import org.neo4j.driver.summary.QueryType;
import org.neo4j.driver.summary.ResultSummary;
import org.neo4j.driver.util.DatabaseExtension;
import org.neo4j.driver.util.ParallelizableIT;
import org.neo4j.driver.util.StdIOCapture;
import org.neo4j.driver.util.TestUtil;

import static java.nio.charset.StandardCharsets.UTF_8;
import static java.util.Arrays.asList;
import static org.hamcrest.Matchers.containsString;
import static org.hamcrest.Matchers.emptyString;
import static org.hamcrest.Matchers.equalTo;
import static org.hamcrest.Matchers.greaterThan;
import static org.hamcrest.Matchers.greaterThanOrEqualTo;
import static org.hamcrest.Matchers.instanceOf;
import static org.hamcrest.Matchers.is;
import static org.hamcrest.Matchers.nullValue;
import static org.hamcrest.junit.MatcherAssert.assertThat;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertThrows;
import static org.junit.jupiter.api.Assertions.assertTrue;
import static org.neo4j.driver.Config.TrustStrategy.trustAllCertificates;
import static org.neo4j.driver.Values.parameters;
import static org.neo4j.driver.internal.util.Neo4jEdition.ENTERPRISE;
import static org.neo4j.driver.internal.util.Neo4jFeature.BOLT_V4;
import static org.neo4j.driver.util.Neo4jRunner.PASSWORD;
import static org.neo4j.driver.util.Neo4jRunner.USER;
import static org.neo4j.driver.util.TestUtil.await;
import static org.neo4j.driver.util.TestUtil.createDatabase;
import static org.neo4j.driver.util.TestUtil.dropDatabase;

@ParallelizableIT
@Execution( ExecutionMode.CONCURRENT )
class ExamplesIT
{
    @RegisterExtension
    static final DatabaseExtension neo4j = new DatabaseExtension();

    private String uri;

    private int readInt( String database, final String query, final Value parameters )
    {
        SessionConfig sessionConfig;
        if ( database == null )
        {
            sessionConfig = SessionConfig.defaultConfig();
        }
        else
        {
            sessionConfig = SessionConfig.forDatabase( database );
        }
        try ( Session session = neo4j.driver().session( sessionConfig ) )
        {
            return session.readTransaction( tx -> tx.run( query, parameters ).single().get( 0 ).asInt() );
        }
    }

    private int readInt( final String query, final Value parameters )
    {
        return readInt( null, query, parameters );
    }

    private int readInt( final String query )
    {
        return readInt( query, parameters() );
    }

    private void write( final String query, final Value parameters )
    {
        try ( Session session = neo4j.driver().session() )
        {
            session.writeTransaction( tx ->
            {
                tx.run( query, parameters );
                return null;
            } );
        }
    }

    private void write( String query )
    {
        write( query, parameters() );
    }

    private int personCount( String name )
    {
        return readInt( "MATCH (a:Person {name: $name}) RETURN count(a)", parameters( "name", name ) );
    }

    private int companyCount( String name )
    {
        return readInt( "MATCH (a:Company {name: $name}) RETURN count(a)", parameters( "name", name ) );
    }

    @BeforeEach
    void setUp()
    {
        uri = neo4j.uri().toString();
        TestUtil.cleanDb( neo4j.driver() );
    }

    @Test
    void testShouldRunAutocommitTransactionExample() throws Exception
    {
        // Given
        try ( AutocommitTransactionExample example = new AutocommitTransactionExample( uri, USER, PASSWORD ) )
        {
            // When
            example.addPerson( "Alice" );

            // Then
            assertThat( personCount( "Alice" ), greaterThan( 0 ) );
        }
    }

    @Test
    void testShouldRunAsyncAutocommitTransactionExample() throws Exception
    {
        try ( AsyncAutocommitTransactionExample example = new AsyncAutocommitTransactionExample( uri, USER, PASSWORD ) )
        {
            // create some 'Product' nodes
            try ( Session session = neo4j.driver().session() )
            {
                session.run(
                        "UNWIND ['Tesseract', 'Orb', 'Eye of Agamotto'] AS item " +
                        "CREATE (:Product {id: 0, title: item})" );
            }

            // read all 'Product' nodes
            List<String> titles = await( example.readProductTitles() );
            assertEquals( new HashSet<>( asList( "Tesseract", "Orb", "Eye of Agamotto" ) ), new HashSet<>( titles ) );
        }
    }

    @Test
    void testShouldAsyncRunResultConsumeExample() throws Exception
    {
        // Given
        write( "CREATE (a:Person {name: 'Alice'})" );
        write( "CREATE (a:Person {name: 'Bob'})" );
        try ( AsyncResultConsumeExample example = new AsyncResultConsumeExample( uri, USER, PASSWORD ) )
        {
            // When
            List<String> names = await( example.getPeople() );

            // Then
            assertThat( names, equalTo( asList( "Alice", "Bob" ) ) );
        }
    }

    @Test
    void testShouldAsyncRunMultipleTransactionExample() throws Exception
    {
        // Given
        write( "CREATE (a:Person {name: 'Alice'})" );
        write( "CREATE (a:Person {name: 'Bob'})" );
        try ( AsyncRunMultipleTransactionExample example = new AsyncRunMultipleTransactionExample( uri, USER, PASSWORD ) )
        {
            // When
            Integer nodesCreated = await( example.addEmployees("Acme") );

            // Then
            int employeeCount = readInt(
                    "MATCH (emp:Person)-[WORKS_FOR]->(com:Company) WHERE com.name = 'Acme' RETURN count(emp)" );
            assertThat( employeeCount, equalTo( 2 ) );
            assertThat( nodesCreated, equalTo( 1 ) );
        }
    }

    @Test
    void testShouldRunConfigConnectionPoolExample() throws Exception
    {
        // Given
        try ( ConfigConnectionPoolExample example = new ConfigConnectionPoolExample( uri, USER, PASSWORD ) )
        {
            // Then
            assertTrue( example.canConnect() );
        }
    }

    @Test
    void testShouldRunBasicAuthExample() throws Exception
    {
        // Given
        try ( BasicAuthExample example = new BasicAuthExample( uri, USER, PASSWORD ) )
        {
            // Then
            assertTrue( example.canConnect() );
        }
    }

    @Test
    void testShouldRunConfigConnectionTimeoutExample() throws Exception
    {
        // Given
        try ( ConfigConnectionTimeoutExample example = new ConfigConnectionTimeoutExample( uri, USER, PASSWORD ) )
        {
            // Then
            assertThat( example, instanceOf( ConfigConnectionTimeoutExample.class ) );
        }
    }

    @Test
    void testShouldRunConfigMaxRetryTimeExample() throws Exception
    {
        // Given
        try ( ConfigMaxRetryTimeExample example = new ConfigMaxRetryTimeExample( uri, USER, PASSWORD ) )
        {
            // Then
            assertThat( example, instanceOf( ConfigMaxRetryTimeExample.class ) );
        }
    }

    @Test
    void testShouldRunConfigTrustExample() throws Exception
    {
        // Given
        try ( ConfigTrustExample example = new ConfigTrustExample( uri, USER, PASSWORD ) )
        {
            // Then
            assertThat( example, instanceOf( ConfigTrustExample.class ) );
        }
    }

    @Test
    void testShouldRunConfigUnencryptedExample() throws Exception
    {
        // Given
        try ( ConfigUnencryptedExample example = new ConfigUnencryptedExample( uri, USER, PASSWORD ) )
        {
            // Then
            assertThat( example, instanceOf( ConfigUnencryptedExample.class ) );
        }
    }

    @Test
    void testShouldRunCypherErrorExample() throws Exception
    {
        // Given
        try ( CypherErrorExample example = new CypherErrorExample( uri, USER, PASSWORD ) )
        {
            // When & Then
            StdIOCapture stdIO = new StdIOCapture();
            try ( AutoCloseable ignored = stdIO.capture() )
            {
                int employeeNumber = example.getEmployeeNumber( "Alice" );

                assertThat( employeeNumber, equalTo( -1 ) );
            }
            assertThat( stdIO.stderr().toString(), containsString( "Invalid input" ) );
        }
    }

    @Test
    void testShouldRunDriverLifecycleExample() throws Exception
    {
        // Given
        try ( DriverLifecycleExample example = new DriverLifecycleExample( uri, USER, PASSWORD ) )
        {
            // Then
            assertThat( example, instanceOf( DriverLifecycleExample.class ) );
        }
    }

    @Test
    void testShouldRunHelloWorld() throws Exception
    {
        // Given
        try ( HelloWorldExample greeter = new HelloWorldExample( uri, USER, PASSWORD ) )
        {
            // When
            StdIOCapture stdIO = new StdIOCapture();

            try ( AutoCloseable ignored = stdIO.capture() )
            {
                greeter.printGreeting( "hello, world" );
            }

            // Then
            assertThat( stdIO.stdout().size(), equalTo( 1 ) );
            assertThat( stdIO.stdout().get( 0 ), containsString( "hello, world" ) );
        }
    }

    @Test
    void testShouldRunDriverIntroduction() throws Exception
    {
        // Given
        Config config = Config.builder().withEncryption().withTrustStrategy(trustAllCertificates()).build();
        try (DriverIntroductionExample intro = new DriverIntroductionExample( uri, USER, PASSWORD, config) )
        {
            // When
            StdIOCapture stdIO = new StdIOCapture();

            try ( AutoCloseable ignored = stdIO.capture() )
            {
                intro.createFriendship( "Alice", "David" );
                intro.findPerson( "Alice" );
            }

            // Then
            assertThat( stdIO.stdout().size(), equalTo( 2 ) );
            assertThat( stdIO.stdout().get( 0 ), containsString( "Created friendship between: Alice, David" ) );
            assertThat( stdIO.stdout().get( 1 ), containsString( "Found person: Alice" ) );
        }
    }

    @Test
    void testShouldRunReadWriteTransactionExample() throws Exception
    {
        // Given
        try ( ReadWriteTransactionExample example = new ReadWriteTransactionExample( uri, USER, PASSWORD ) )
        {
            // When
            long nodeID = example.addPerson( "Alice" );

            // Then
            assertThat( nodeID, greaterThanOrEqualTo( 0L ) );
        }
    }

    @Test
    void testShouldRunResultConsumeExample() throws Exception
    {
        // Given
        write( "CREATE (a:Person {name: 'Alice'})" );
        write( "CREATE (a:Person {name: 'Bob'})" );
        try ( ResultConsumeExample example = new ResultConsumeExample( uri, USER, PASSWORD ) )
        {
            // When
            List<String> names = example.getPeople();

            // Then
            assertThat( names, equalTo( asList( "Alice", "Bob" ) ) );
        }
    }

    @Test
    void testShouldRunResultRetainExample() throws Exception
    {
        // Given
        write( "CREATE (a:Person {name: 'Alice'})" );
        write( "CREATE (a:Person {name: 'Bob'})" );
        try ( ResultRetainExample example = new ResultRetainExample( uri, USER, PASSWORD ) )
        {
            // When
            example.addEmployees( "Acme" );

            // Then
            int employeeCount = readInt(
                    "MATCH (emp:Person)-[WORKS_FOR]->(com:Company) WHERE com.name = 'Acme' RETURN count(emp)" );
            assertThat( employeeCount, equalTo( 2 ) );
        }
    }

    @Test
    void testShouldRunServiceUnavailableExample() throws Exception
    {
        // Given
        try ( ServiceUnavailableExample example = new ServiceUnavailableExample( uri, USER, PASSWORD ) )
        {
            try
            {
                // When
                neo4j.stopDb();

                // Then
                assertThat( example.addItem(), equalTo( false ) );
            }
            finally
            {
                neo4j.startDb();
            }
        }
    }

    @Test
    void testShouldRunSessionExample() throws Exception
    {
        // Given
        try ( SessionExample example = new SessionExample( uri, USER, PASSWORD ) )
        {
            // When
            example.addPerson( "Alice" );

            // Then
            assertThat( example, instanceOf( SessionExample.class ) );
            assertThat( personCount( "Alice" ), greaterThan( 0 ) );
        }
    }

    @Test
    void testShouldRunTransactionFunctionExample() throws Exception
    {
        // Given
        try ( TransactionFunctionExample example = new TransactionFunctionExample( uri, USER, PASSWORD ) )
        {
            // When
            example.addPerson( "Alice" );

            // Then
            assertThat( personCount( "Alice" ), greaterThan( 0 ) );
        }
    }

    @Test
    void testShouldRunAsyncTransactionFunctionExample() throws Exception
    {
        try ( AsyncTransactionFunctionExample example = new AsyncTransactionFunctionExample( uri, USER, PASSWORD ) )
        {
            // create some 'Product' nodes
            try ( Session session = neo4j.driver().session() )
            {
                session.run(
                        "UNWIND ['Infinity Gauntlet', 'Mjölnir'] AS item " +
                        "CREATE (:Product {id: 0, title: item})" );
            }

            StdIOCapture stdIOCapture = new StdIOCapture();

            // print all 'Product' nodes to fake stdout
            try ( AutoCloseable ignore = stdIOCapture.capture() )
            {
                ResultSummary summary = await( example.printAllProducts() );
                assertEquals( QueryType.READ_ONLY, summary.queryType() );
            }

            Set<String> capturedOutput = new HashSet<>( stdIOCapture.stdout() );
            assertEquals( new HashSet<>( asList( "Infinity Gauntlet", "Mjölnir" ) ), capturedOutput );
        }
    }

    @Test
    void testPassBookmarksExample() throws Exception
    {
        try ( PassBookmarkExample example = new PassBookmarkExample( uri, USER, PASSWORD ) )
        {
            // When
            example.addEmployAndMakeFriends();

            // Then
            assertThat( companyCount( "Wayne Enterprises" ), is( 1 ) );
            assertThat( companyCount( "LexCorp" ), is( 1 ) );
            assertThat( personCount( "Alice" ), is( 1 ) );
            assertThat( personCount( "Bob" ), is( 1 ) );

            int employeeCountOfWayne = readInt(
                    "MATCH (emp:Person)-[WORKS_FOR]->(com:Company) WHERE com.name = 'Wayne Enterprises' RETURN count(emp)" );
            assertThat( employeeCountOfWayne, is( 1 ) );

            int employeeCountOfLexCorp = readInt(
                    "MATCH (emp:Person)-[WORKS_FOR]->(com:Company) WHERE com.name = 'LexCorp' RETURN count(emp)" );
            assertThat( employeeCountOfLexCorp, is( 1 ) );

            int friendCount = readInt(
                    "MATCH (a:Person {name: 'Alice'})-[:KNOWS]->(b:Person {name: 'Bob'}) RETURN count(a)" );
            assertThat( friendCount, is( 1 ) );
        }
    }

    @Test
    void testAsyncUnmanagedTransactionExample() throws Exception
    {
        try ( AsyncUnmanagedTransactionExample example = new AsyncUnmanagedTransactionExample( uri, USER, PASSWORD ) )
        {
            // create a 'Product' node
            try ( Session session = neo4j.driver().session() )
            {
                session.run( "CREATE (:Product {id: 0, title: 'Mind Gem'})" );
            }

            StdIOCapture stdIOCapture = new StdIOCapture();

            // print the single 'Product' node
            try ( AutoCloseable ignore = stdIOCapture.capture() )
            {
                await( example.printSingleProduct() );
            }

            assertEquals( 1, stdIOCapture.stdout().size() );
            assertEquals( "Mind Gem", stdIOCapture.stdout().get( 0 ) );
        }
    }

    @Test
    void testSlf4jLogging() throws Exception
    {
        // log file is defined in logback-test.xml configuration file
        Path logFile = Paths.get( "target", "test.log" );
        if ( Files.exists( logFile ) )
        {
            // delete file made this test flaky
            // erase content instead
            Files.write( logFile, new byte[0] );
        }

        // verify erased
        String logFileContent = new String( Files.readAllBytes( logFile ), UTF_8 );
        assertThat( logFileContent, is( emptyString() ) );

        String randomString = UUID.randomUUID().toString();
        try ( Slf4jLoggingExample example = new Slf4jLoggingExample( uri, USER, PASSWORD ) )
        {
            Object result = example.runReturnQuery( randomString );
            assertEquals( randomString, result );
        }
        assertTrue( Files.exists( logFile ) );

        logFileContent = new String( Files.readAllBytes( logFile ), UTF_8 );
        assertThat( logFileContent, containsString( "RETURN $x" ) );
        assertThat( logFileContent, containsString( randomString ) );

    }

    @Test
    void testHostnameVerificationExample()
    {
        try ( HostnameVerificationExample example = new HostnameVerificationExample( uri, USER, PASSWORD, neo4j.tlsCertFile() ) )
        {
            assertTrue( example.canConnect() );
        }
    }

    @Test
    @EnabledOnNeo4jWith( BOLT_V4 )
    void testShouldRunRxAutocommitTransactionExample() throws Exception
    {
        try ( RxAutocommitTransactionExample example = new RxAutocommitTransactionExample( uri, USER, PASSWORD ) )
        {
            // create some 'Product' nodes
            try ( Session session = neo4j.driver().session() )
            {
                session.run(
                        "UNWIND ['Tesseract', 'Orb', 'Eye of Agamotto'] AS item " +
                                "CREATE (:Product {id: 0, title: item})" );
            }

            // read all 'Product' nodes
            List<String> titles = await( example.readProductTitles() );
            assertEquals( new HashSet<>( asList( "Tesseract", "Orb", "Eye of Agamotto" ) ), new HashSet<>( titles ) );

            titles = await( example.readProductTitlesRxJava() );
            assertEquals( new HashSet<>( asList( "Tesseract", "Orb", "Eye of Agamotto" ) ), new HashSet<>( titles ) );
        }
    }

    @Test
    @EnabledOnNeo4jWith( BOLT_V4 )
    void testRxUnmanagedTransactionExample() throws Exception
    {
        try ( RxUnmanagedTransactionExample example = new RxUnmanagedTransactionExample( uri, USER, PASSWORD ) )
        {
            // create a 'Product' node
            try ( Session session = neo4j.driver().session() )
            {
                session.run( "CREATE (:Product {id: 0, title: 'Mind Gem'})" );
            }

            List<String> products = await( example.readSingleProduct() );
            assertEquals( 1, products.size() );
            assertEquals( "Mind Gem", products.get( 0 ) );

            products = await( example.readSingleProductRxJava() );
            assertEquals( 1, products.size() );
            assertEquals( "Mind Gem", products.get( 0 ) );

        }
    }

    @Test
    @EnabledOnNeo4jWith( BOLT_V4 )
    void testShouldRunRxTransactionFunctionExampleReactor() throws Exception
    {
        try ( RxTransactionFunctionExample example = new RxTransactionFunctionExample( uri, USER, PASSWORD ) )
        {
            // create some 'Product' nodes
            try ( Session session = neo4j.driver().session() )
            {
                session.run(
                        "UNWIND ['Infinity Gauntlet', 'Mjölnir'] AS item " +
                                "CREATE (:Product {id: 0, title: item})" );
            }

            StdIOCapture stdIOCapture = new StdIOCapture();

            // print all 'Product' nodes to fake stdout
            try ( AutoCloseable ignore = stdIOCapture.capture() )
            {
                final List<ResultSummary> summaryList = await( example.printAllProducts() );
                assertThat( summaryList.size(), equalTo( 1 ) );
                ResultSummary summary = summaryList.get( 0 );
                assertEquals( QueryType.READ_ONLY, summary.queryType() );
            }

            Set<String> capturedOutput = new HashSet<>( stdIOCapture.stdout() );
            assertEquals( new HashSet<>( asList( "Infinity Gauntlet", "Mjölnir" ) ), capturedOutput );
        }
    }

    @Test
    @EnabledOnNeo4jWith( BOLT_V4 )
    void testShouldRunRxTransactionFunctionExampleRxJava() throws Exception
    {
        try ( RxTransactionFunctionExample example = new RxTransactionFunctionExample( uri, USER, PASSWORD ) )
        {
            // create some 'Product' nodes
            try ( Session session = neo4j.driver().session() )
            {
                session.run(
                        "UNWIND ['Infinity Gauntlet', 'Mjölnir'] AS item " +
                                "CREATE (:Product {id: 0, title: item})" );
            }

            StdIOCapture stdIOCapture = new StdIOCapture();

            // print all 'Product' nodes to fake stdout
            try ( AutoCloseable ignore = stdIOCapture.capture() )
            {
                final List<ResultSummary> summaryList = await( example.printAllProductsRxJava() );
                assertThat( summaryList.size(), equalTo( 1 ) );
                ResultSummary summary = summaryList.get( 0 );
                assertEquals( QueryType.READ_ONLY, summary.queryType() );
            }

            Set<String> capturedOutput = new HashSet<>( stdIOCapture.stdout() );
            assertEquals( new HashSet<>( asList( "Infinity Gauntlet", "Mjölnir" ) ), capturedOutput );
        }
    }

    @Test
    @EnabledOnNeo4jWith( BOLT_V4 )
    void testShouldRunRxResultConsumeExampleReactor() throws Exception
    {
        // Given
        write( "CREATE (a:Person {name: 'Alice'})" );
        write( "CREATE (a:Person {name: 'Bob'})" );
        try ( RxResultConsumeExample example = new RxResultConsumeExample( uri, USER, PASSWORD ) )
        {
            // When
            List<String> names = await( example.getPeople() );

            // Then
            assertThat( names, equalTo( asList( "Alice", "Bob" ) ) );
        }
    }

    @Test
    @EnabledOnNeo4jWith( BOLT_V4 )
    void testShouldRunRxResultConsumeExampleRxJava() throws Exception
    {
        // Given
        write( "CREATE (a:Person {name: 'Alice'})" );
        write( "CREATE (a:Person {name: 'Bob'})" );
        try ( RxResultConsumeExample example = new RxResultConsumeExample( uri, USER, PASSWORD ) )
        {
            // When
            List<String> names = await( example.getPeopleRxJava() );

            // Then
            assertThat( names, equalTo( asList( "Alice", "Bob" ) ) );
        }
    }

    @Test
    @EnabledOnNeo4jWith( value = BOLT_V4, edition = ENTERPRISE)
    void testUseAnotherDatabaseExample() throws Exception
    {
        Driver driver = neo4j.driver();
        dropDatabase( driver, "examples" );
        createDatabase( driver, "examples" );

        try ( DatabaseSelectionExample example = new DatabaseSelectionExample( uri, USER, PASSWORD ) )
        {
            // When
            example.useAnotherDatabaseExample();

            // Then
            int greetingCount = readInt( "examples", "MATCH (a:Greeting) RETURN count(a)", Values.parameters() );
            assertThat( greetingCount, is( 1 ) );
        }
    }

    @Test
    void testReadingValuesExample() throws Exception
    {
        try (ReadingValuesExample example = new ReadingValuesExample( uri, USER, PASSWORD ))
        {
            assertThat( example.integerFieldIsNull(), is(false) );
            assertThat( example.integerAsInteger(), is( 4 ) );
            assertThat( example.integerAsLong(), is( 4L ) );
            assertThrows( Uncoercible.class, example::integerAsString );

            assertThat( example.nullIsNull(), is(true) );
            assertThat( example.nullAsString(), is( "null" ) );
            assertThat( example.nullAsObject(), nullValue());
            assertThat( example.nullAsObjectFloatDefaultValue(), is( 1.0f ) );
            assertThrows( Uncoercible.class, example::nullAsObjectFloat );
        }
    }
}