Create delayed injection test runner

- Test runner supporting new "DelayedInjection" annotation: such fields are only initialized with instantiation right before the first time they're used in tests, allowing to set up mock behavior beforehand

src/main/java/fr/xephi/authme/initialization/AuthMeServiceInitializer.java

@@ -5,7 +5,6 @@ import com.google.common.collect.ImmutableSet;
 import fr.xephi.authme.settings.NewSetting;
 
 import javax.annotation.PostConstruct;
-import javax.inject.Provider;
 import java.lang.annotation.Annotation;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
@@ -167,8 +166,7 @@ public class AuthMeServiceInitializer {
      * @return the instantiated object
      */
     private <T> T instantiate(Class<T> clazz, Set<Class<?>> traversedClasses) {
-        Injection<T> injection = firstNotNull(
-            ConstructorInjection.provide(clazz), FieldInjection.provide(clazz), InstantiationFallback.provide(clazz));
+        Injection<T> injection = InjectionHelper.getInjection(clazz);
         if (injection == null) {
             throw new IllegalStateException("Did not find injection method for " + clazz + ". Make sure you have "
                 + "a constructor with @Inject or fields with @Inject. Fields with @Inject require "
@@ -268,7 +266,7 @@ public class AuthMeServiceInitializer {
      * @param object the object to execute the post construct method for
      */
     private static void executePostConstructMethod(Object object) {
-        Method postConstructMethod = getAndValidatePostConstructMethod(object.getClass());
+        Method postConstructMethod = InjectionHelper.getAndValidatePostConstructMethod(object.getClass());
         if (postConstructMethod != null) {
             try {
                 postConstructMethod.setAccessible(true);
@@ -285,40 +283,4 @@ public class AuthMeServiceInitializer {
         }
     }
 
-    /**
-     * Validate and locate the given class' post construct method. Returns {@code null} if none present.
-     *
-     * @param clazz the class to search
-     * @return post construct method, or null
-     */
-    private static Method getAndValidatePostConstructMethod(Class<?> clazz) {
-        Method postConstructMethod = null;
-        for (Method method : clazz.getDeclaredMethods()) {
-            if (method.isAnnotationPresent(PostConstruct.class)) {
-                if (postConstructMethod != null) {
-                    throw new IllegalStateException("Multiple methods with @PostConstruct on " + clazz);
-                } else if (method.getParameterTypes().length > 0 || Modifier.isStatic(method.getModifiers())) {
-                    throw new IllegalStateException("@PostConstruct method may not be static or have any parameters. "
-                        + "Invalid method in " + clazz);
-                } else if (method.getReturnType() != void.class) {
-                    throw new IllegalStateException("@PostConstruct method must have return type void. "
-                        + "Offending class: " + clazz);
-                } else {
-                    postConstructMethod = method;
-                }
-            }
-        }
-        return postConstructMethod;
-    }
-
-    @SafeVarargs
-    private static <T> Injection<T> firstNotNull(Provider<? extends Injection<T>>... providers) {
-        for (Provider<? extends Injection<T>> provider : providers) {
-            Injection<T> object = provider.get();
-            if (object != null) {
-                return object;
-            }
-        }
-        return null;
-    }
 }

src/main/java/fr/xephi/authme/initialization/ConstructorInjection.java

@@ -11,7 +11,7 @@ import java.lang.reflect.InvocationTargetException;
 /**
  * Functionality for constructor injection.
  */
-public class ConstructorInjection<T> implements Injection<T> {
+class ConstructorInjection<T> implements Injection<T> {
 
     private final Constructor<T> constructor;
 

src/main/java/fr/xephi/authme/initialization/FieldInjection.java

@@ -16,7 +16,7 @@ import java.util.List;
 /**
  * Functionality for field injection.
  */
-public class FieldInjection<T> implements Injection<T> {
+class FieldInjection<T> implements Injection<T> {
 
     private final Field[] fields;
     private final Constructor<T> defaultConstructor;

src/main/java/fr/xephi/authme/initialization/InjectionHelper.java

@@ -0,0 +1,66 @@
+package fr.xephi.authme.initialization;
+
+import javax.annotation.PostConstruct;
+import javax.inject.Provider;
+import java.lang.reflect.Method;
+import java.lang.reflect.Modifier;
+
+/**
+ * Helper class for functions relating to injecting.
+ */
+public class InjectionHelper {
+
+    private InjectionHelper() {
+    }
+
+    /**
+     * Returns the {@link Injection} for the given class, or null if none applicable.
+     *
+     * @param clazz the class to process
+     * @param <T> the class' type
+     * @return injection of the class or null if none detected
+     */
+    public static <T> Injection<T> getInjection(Class<T> clazz) {
+        return firstNotNull(
+            ConstructorInjection.provide(clazz),
+            FieldInjection.provide(clazz),
+            InstantiationFallback.provide(clazz));
+    }
+
+    /**
+     * Validates and locates the given class' post construct method. Returns {@code null} if none present.
+     *
+     * @param clazz the class to search
+     * @return post construct method, or null
+     */
+    public static Method getAndValidatePostConstructMethod(Class<?> clazz) {
+        Method postConstructMethod = null;
+        for (Method method : clazz.getDeclaredMethods()) {
+            if (method.isAnnotationPresent(PostConstruct.class)) {
+                if (postConstructMethod != null) {
+                    throw new IllegalStateException("Multiple methods with @PostConstruct on " + clazz);
+                } else if (method.getParameterTypes().length > 0 || Modifier.isStatic(method.getModifiers())) {
+                    throw new IllegalStateException("@PostConstruct method may not be static or have any parameters. "
+                        + "Invalid method in " + clazz);
+                } else if (method.getReturnType() != void.class) {
+                    throw new IllegalStateException("@PostConstruct method must have return type void. "
+                        + "Offending class: " + clazz);
+                } else {
+                    postConstructMethod = method;
+                }
+            }
+        }
+        return postConstructMethod;
+    }
+
+    @SafeVarargs
+    private static <T> Injection<T> firstNotNull(Provider<? extends Injection<T>>... providers) {
+        for (Provider<? extends Injection<T>> provider : providers) {
+            Injection<T> object = provider.get();
+            if (object != null) {
+                return object;
+            }
+        }
+        return null;
+    }
+}

src/main/java/fr/xephi/authme/initialization/InstantiationFallback.java

@@ -11,7 +11,7 @@ import java.lang.reflect.InvocationTargetException;
  * Fallback instantiation method for classes with an accessible no-args constructor
  * and no elements whatsoever annotated with {@link Inject} or {@link PostConstruct}.
  */
-public class InstantiationFallback<T> implements Injection<T> {
+class InstantiationFallback<T> implements Injection<T> {
 
     private final Constructor<T> constructor;