package impl;

import api.BetterInstanceProvider;

import api.InstanceProvider;

import org.junit.After;

import org.junit.AfterClass;

import org.junit.Before;

import org.junit.BeforeClass;

import org.junit.Test;

import static org.junit.Assert.*;

public class InstanceProviderTest {

    public InstanceProviderTest() {

    }

    @BeforeClass

    public static void setUpClass() throws Exception {

    }

    @AfterClass

    public static void tearDownClass() throws Exception {

    }

    @Before

    public void setUp() {

    }

    @After

    public void tearDown() {

    }

    @Test

    public void verifyBehaviourOnOldInterface() {

        class IP implements InstanceProvider {

            int instanceClass;

            int instanceCreate;

            public Class<?> instanceClass() {

                instanceClass++;

                return String.class;

            }

            public Object instanceCreate() {

                instanceCreate++;

                return "API Design!";

            }

        }

        IP instance = new IP();

        boolean isString = checkIsString(instance);

        assertTrue("Provides string", isString);

        assertEquals("Class was tested", 1, instance.instanceClass);

        assertEquals("No instance created", 0, instance.instanceCreate);

    }

    @Test

    public void verifyBehaviourOnNewInterface() {

        class IP implements BetterInstanceProvider {

            int isInstanceOf;

            int instanceClass;

            int instanceCreate;

            public Class<?> instanceClass() {

                instanceClass++;

                return String.class;

            }

            public Object instanceCreate() {

                instanceCreate++;

                return "API Design!";

            }

            public boolean isInstanceOf(Class<?> c) {

                isInstanceOf++;

                return c.isAssignableFrom(String.class);

            }

        }

        IP instance = new IP();

        boolean isString = checkIsString(instance);

        assertTrue("Provides string", isString);

        assertEquals("Class was not tested", 0, instance.instanceClass);

        assertEquals("No instance created", 0, instance.instanceCreate);

        assertEquals("isInstanceOf called", 1, instance.isInstanceOf);

    }

    private static boolean checkIsString(InstanceProvider instance) {

        // BEGIN: instanceof.Use

        if (instance instanceof BetterInstanceProvider) {

            BetterInstanceProvider bip = (BetterInstanceProvider)instance;

            return bip.isInstanceOf(String.class);

        } else {

            return String.class.isAssignableFrom(instance.instanceClass());

        }

        // END: instanceof.Use

    }

}