lazy: Implement Lazy<T>, very much like Dagger's.

1 files changed, 243 insertions, 0 deletions

diff --git a/sangria-lazy/src/test/java/com/tavianator/sangria/lazy/LazyTest.java b/sangria-lazy/src/test/java/com/tavianator/sangria/lazy/LazyTest.java
new file mode 100644
index 0000000..ff63c03
--- /dev/null
+++ b/sangria-lazy/src/test/java/com/tavianator/sangria/lazy/LazyTest.java
@@ -0,0 +1,243 @@
+/****************************************************************************
+ * Sangria                                                                  *
+ * Copyright (C) 2014 Tavian Barnes <tavianator@tavianator.com>             *
+ *                                                                          *
+ * 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 com.tavianator.sangria.lazy;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.util.*;
+import javax.inject.Inject;
+import javax.inject.Qualifier;
+
+import com.google.inject.AbstractModule;
+import com.google.inject.Binding;
+import com.google.inject.CreationException;
+import com.google.inject.Guice;
+import com.google.inject.Injector;
+import com.google.inject.Key;
+import com.google.inject.Module;
+import com.google.inject.spi.DefaultBindingTargetVisitor;
+import com.google.inject.spi.Element;
+import com.google.inject.spi.Elements;
+import org.junit.Test;
+
+import static org.hamcrest.Matchers.*;
+import static org.junit.Assert.*;
+
+/**
+ * Tests for {@link Lazy} injection.
+ *
+ * @author Tavian Barnes (tavianator@tavianator.com)
+ * @version 1.2
+ * @since 1.2
+ */
+public class LazyTest {
+    @Retention(RetentionPolicy.RUNTIME)
+    @Qualifier
+    private @interface Simple {
+    }
+
+    private interface Abstract {
+    }
+
+    private static class Concrete implements Abstract {
+        static final ThreadLocal<Integer> INSTANCES = new ThreadLocal<Integer>() {
+            @Override
+            protected Integer initialValue() {
+                return 0;
+            }
+        };
+
+        @Inject
+        Concrete() {
+            INSTANCES.set(INSTANCES.get() + 1);
+        }
+    }
+
+    private static class HasConcrete {
+        @Inject Lazy<Concrete> lazy;
+    }
+
+    private static class HasQualifiedAbstract {
+        @Inject @Simple Lazy<Abstract> lazy;
+    }
+
+    @Test
+    public void testJustInTime() {
+        testHasConcrete(Guice.createInjector());
+    }
+
+    @Test
+    public void testExplicitBindings() {
+        testHasConcrete(Guice.createInjector(new AbstractModule() {
+            @Override
+            protected void configure() {
+                binder().requireExplicitBindings();
+
+                bind(Concrete.class);
+                LazyBinder.create(binder())
+                        .bind(Concrete.class);
+            }
+        }));
+    }
+
+    private void testHasConcrete(Injector injector) {
+        int before = Concrete.INSTANCES.get();
+
+        HasConcrete hasConcrete = new HasConcrete();
+        injector.injectMembers(hasConcrete);
+        assertThat(Concrete.INSTANCES.get(), equalTo(before));
+
+        Concrete instance = hasConcrete.lazy.get();
+        assertThat(Concrete.INSTANCES.get(), equalTo(before + 1));
+
+        Concrete instance2 = hasConcrete.lazy.get();
+        assertThat(instance2, sameInstance(instance));
+        assertThat(Concrete.INSTANCES.get(), equalTo(before + 1));
+
+        HasConcrete hasConcrete2 = new HasConcrete();
+        injector.injectMembers(hasConcrete2);
+        assertThat(Concrete.INSTANCES.get(), equalTo(before + 1));
+
+        Concrete instance3 = hasConcrete2.lazy.get();
+        assertThat(instance3, not(sameInstance(instance)));
+        assertThat(Concrete.INSTANCES.get(), equalTo(before + 2));
+    }
+
+    @Test
+    public void testBindSeparately() {
+        testQualifiedAbstract(Guice.createInjector(new AbstractModule() {
+            @Override
+            protected void configure() {
+                bind(Abstract.class)
+                        .annotatedWith(Simple.class)
+                        .to(Concrete.class);
+
+                LazyBinder.create(binder())
+                        .bind(Abstract.class)
+                        .annotatedWith(Simple.class);
+            }
+        }));
+    }
+
+    @Test
+    public void testBindTogether() {
+        testQualifiedAbstract(Guice.createInjector(new AbstractModule() {
+            @Override
+            protected void configure() {
+                LazyBinder.create(binder())
+                        .bind(Abstract.class)
+                        .annotatedWith(Simple.class)
+                        .to(Concrete.class);
+            }
+        }));
+    }
+
+    private void testQualifiedAbstract(Injector injector) {
+        int before = Concrete.INSTANCES.get();
+
+        HasQualifiedAbstract hasQualifiedAbstract = new HasQualifiedAbstract();
+        injector.injectMembers(hasQualifiedAbstract);
+        assertThat(Concrete.INSTANCES.get(), equalTo(before));
+
+        Abstract instance = hasQualifiedAbstract.lazy.get();
+        assertThat(Concrete.INSTANCES.get(), equalTo(before + 1));
+
+        Abstract instance2 = hasQualifiedAbstract.lazy.get();
+        assertThat(instance2, sameInstance(instance2));
+        assertThat(Concrete.INSTANCES.get(), equalTo(before + 1));
+
+        HasQualifiedAbstract hasQualifiedAbstract2 = new HasQualifiedAbstract();
+        injector.injectMembers(hasQualifiedAbstract2);
+        assertThat(Concrete.INSTANCES.get(), equalTo(before + 1));
+
+        Abstract instance3 = hasQualifiedAbstract2.lazy.get();
+        assertThat(instance3, not(sameInstance(instance)));
+        assertThat(Concrete.INSTANCES.get(), equalTo(before + 2));
+    }
+
+    @Test(expected = CreationException.class)
+    public void testMissingBinding() {
+        Guice.createInjector(new AbstractModule() {
+            @Override
+            protected void configure() {
+                LazyBinder.create(binder())
+                        .bind(Abstract.class);
+            }
+        });
+    }
+
+    @Test(expected = CreationException.class)
+    public void testMissingQualifiedBinding() {
+        Guice.createInjector(new AbstractModule() {
+            @Override
+            protected void configure() {
+                LazyBinder.create(binder())
+                        .bind(Abstract.class)
+                        .annotatedWith(Simple.class);
+            }
+        });
+    }
+
+    private static class TestVisitor<T> extends DefaultBindingTargetVisitor<T, Boolean> implements LazyBindingVisitor<T, Boolean> {
+        @Override
+        public Boolean visit(LazyBinding<? extends T> binding) {
+            assertThat(binding.getTargetKey().equals(new Key<Abstract>(Simple.class) { }), is(true));
+            return true;
+        }
+
+        @Override
+        protected Boolean visitOther(Binding<? extends T> binding) {
+            return false;
+        }
+    }
+
+    private <T> boolean visit(Binding<T> binding) {
+        return binding.acceptTargetVisitor(new TestVisitor<T>());
+    }
+
+    @Test
+    public void testExtensionSpi() {
+        Module module = new AbstractModule() {
+            @Override
+            protected void configure() {
+                // TODO: Expose the SPI for unqualified bindings
+                LazyBinder.create(binder())
+                        .bind(Abstract.class)
+                        .annotatedWith(Simple.class)
+                        .to(Concrete.class);
+            }
+        };
+
+        List<Element> elements = Elements.getElements(module);
+
+        int passed = 0;
+        for (Element element : elements) {
+            if (element instanceof Binding) {
+                if (visit((Binding<?>)element)) {
+                    ++passed;
+                }
+            }
+        }
+        assertThat(passed, equalTo(1));
+
+        Injector injector = Guice.createInjector(Elements.getModule(elements));
+        assertThat(visit(injector.getBinding(new Key<Lazy<Abstract>>(Simple.class) { })), is(true));
+        assertThat(visit(injector.getBinding(new Key<Abstract>(Simple.class) { })), is(false));
+        assertThat(visit(injector.getBinding(new Key<Concrete>() { })), is(false));
+    }
+}