java-interview-lab/junit-mockito/src/test/java/lab/jm/fixtures/ExtensionFixtures.java

package lab.jm.fixtures;

import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.TestInfo;
import org.junit.jupiter.api.extension.AfterAllCallback;
import org.junit.jupiter.api.extension.AfterEachCallback;
import org.junit.jupiter.api.extension.AfterTestExecutionCallback;
import org.junit.jupiter.api.extension.BeforeAllCallback;
import org.junit.jupiter.api.extension.BeforeEachCallback;
import org.junit.jupiter.api.extension.BeforeTestExecutionCallback;
import org.junit.jupiter.api.extension.ExtendWith;
import org.junit.jupiter.api.extension.ExtensionContext;
import org.junit.jupiter.api.extension.ParameterContext;
import org.junit.jupiter.api.extension.ParameterResolver;
import org.junit.jupiter.api.extension.RegisterExtension;

public final class ExtensionFixtures {
    private ExtensionFixtures() {
    }

    /** Logs every callback it receives, tagged with a label. */
    public static class Tracer implements BeforeAllCallback, BeforeEachCallback,
            BeforeTestExecutionCallback, AfterTestExecutionCallback, AfterEachCallback, AfterAllCallback {
        private final String label;

        public Tracer() {
            this("declared");
        }

        public Tracer(String label) {
            this.label = label;
        }

        @Override
        public void beforeAll(ExtensionContext c) {
            Log.add(label + ": beforeAll");
        }

        @Override
        public void beforeEach(ExtensionContext c) {
            Log.add(label + ": beforeEach");
        }

        @Override
        public void beforeTestExecution(ExtensionContext c) {
            Log.add(label + ": beforeTestExecution");
        }

        @Override
        public void afterTestExecution(ExtensionContext c) {
            Log.add(label + ": afterTestExecution");
        }

        @Override
        public void afterEach(ExtensionContext c) {
            Log.add(label + ": afterEach");
        }

        @Override
        public void afterAll(ExtensionContext c) {
            Log.add(label + ": afterAll");
        }
    }

    /** One declarative extension, to show the callback order around a test and its @BeforeEach method. */
    @ExtendWith(Tracer.class)
    public static class CallbackOrder {
        @BeforeEach
        void beforeEachMethod() {
            Log.add("test class: @BeforeEach method");
        }

        @Test
        void theTest() {
            Log.add("test class: the test body");
        }
    }

    /** Declarative (@ExtendWith) and programmatic (@RegisterExtension) side by side. */
    @ExtendWith(Tracer.class)
    public static class Registration {
        @RegisterExtension
        static final Tracer PROGRAMMATIC = new Tracer("programmatic(static field)");

        @Test
        void theTest() {
            Log.add("test body");
        }
    }

    /** A value the custom resolver hands to tests. */
    public record Tenant(String name) {
    }

    /** Resolves Tenant parameters, in constructors and in test methods alike. */
    public static class TenantResolver implements ParameterResolver {
        @Override
        public boolean supportsParameter(ParameterContext p, ExtensionContext c) {
            return p.getParameter().getType() == Tenant.class;
        }

        @Override
        public Object resolveParameter(ParameterContext p, ExtensionContext c) {
            return new Tenant("tenant-for-" + c.getRequiredTestMethod().getName());
        }
    }

    @ExtendWith(TenantResolver.class)
    public static class Injection {
        @Test
        void resolvesCustomAndBuiltIn(Tenant tenant, TestInfo info) {
            Log.add("custom parameter : " + tenant);
            Log.add("built-in TestInfo: displayName=" + info.getDisplayName());
        }
    }
}