Fixing lazy sync problem

Using properly Double-checked locking pattern for Lazy and
SerializableLazy classes. Additionally, adding more test to
cover the introduced code.

src/main/java/pl/wavesoftware/eid/impl/Lazy.java

@@ -24,7 +24,7 @@
  * @since 2.0.0
  */
 class Lazy<T> implements Supplier<T> {
-    private Supplier<T> supplier;
+    private volatile Supplier<T> supplier;
     private T value;
 
     Lazy(Supplier<T> supplier) {
@@ -50,16 +50,13 @@ static <R> Lazy<R> of(R value) {
     @Override
     public T get() {
         if (supplier != null) {
-            value = doGet();
-        }
-        return value;
-    }
-
-    private synchronized T doGet() {
-        if (supplier != null) {
-            T calculated = supplier.get();
-            supplier = null;
-            return calculated;
+            synchronized (this) {
+                if (supplier != null) {
+                    T calculated = supplier.get();
+                    supplier = null;
+                    value = calculated;
+                }
+            }
         }
         return value;
     }

src/main/java/pl/wavesoftware/eid/impl/SerializableLazy.java

@@ -29,7 +29,7 @@ final class SerializableLazy<T extends Serializable>
     implements SerializableSupplier<T> {
 
     private static final long serialVersionUID = 20181124011908L;
-    private T serializable;
+    private volatile T serializable;
 
     private SerializableLazy(Supplier<T> supplier) {
         super(supplier);
@@ -42,14 +42,11 @@ static <R extends Serializable> SerializableLazy<R> serializableOf(Supplier<R> s
     @Override
     public T get() {
         if (serializable == null) {
-            serializable = doGetFromParent();
-        }
-        return serializable;
-    }
-
-    private synchronized T doGetFromParent() {
-        if (serializable == null) {
-            return super.get();
+            synchronized (this) {
+                if (serializable == null) {
+                    serializable = super.get();
+                }
+            }
         }
         return serializable;
     }

src/test/java/pl/wavesoftware/eid/impl/DefaultFormatterTest.java

@@ -0,0 +1,87 @@
+/*
+ * Copyright (c) 2018 Wave Software
+ *
+ * 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 pl.wavesoftware.eid.impl;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import pl.wavesoftware.eid.Eid;
+import pl.wavesoftware.eid.configuration.Configuration;
+import pl.wavesoftware.eid.configuration.ConfigurationBuilder;
+import pl.wavesoftware.eid.configuration.Configurator;
+import pl.wavesoftware.eid.configuration.Formatter;
+import pl.wavesoftware.eid.configuration.UniqueIdGenerator;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author <a href="mailto:krzysztof.suszynski@wavesoftware.pl">Krzysztof Suszynski</a>
+ * @since 2018-12-03
+ */
+public class DefaultFormatterTest {
+
+    private Configurator restore;
+
+    @Before
+    public void before() {
+        restore = Eid.getBinding().getConfigurationSystem().configure(new Configurator() {
+            @Override
+            public void configure(ConfigurationBuilder configuration) {
+                configuration.uniqueIdGenerator(new UniqueIdGenerator() {
+                    @Override
+                    public String generateUniqId() {
+                        return "deadcafe";
+                    }
+                });
+            }
+        });
+    }
+
+    @After
+    public void after() {
+        Eid.getBinding().getConfigurationSystem().configure(restore);
+    }
+
+    @Test
+    public void format() {
+        // given
+        Configuration configuration = new ConfigurationImpl();
+        Formatter formatter = new DefaultFormatter(configuration);
+
+        // when
+        String formatted = formatter.format(new Eid("20181203:224055"));
+
+        // then
+        assertThat(formatted).isEqualTo("[20181203:224055]<deadcafe>");
+    }
+
+    @Test
+    public void formatWithMessage() {
+        // given
+        Configuration configuration = new ConfigurationImpl();
+        Formatter formatter = new DefaultFormatter(configuration);
+
+        // when
+        String formatted = formatter.format(
+            new Eid("20181203:224137"),
+            "a message"
+        );
+
+        // then
+        assertThat(formatted).isEqualTo("[20181203:224137]<deadcafe> => a message");
+    }
+}

src/test/java/pl/wavesoftware/eid/impl/InternalChecksTest.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright (c) 2018 Wave Software
+ *
+ * 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 pl.wavesoftware.eid.impl;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+
+import static org.assertj.core.api.Assertions.*;
+
+/**
+ * @author <a href="mailto:krzysztof.suszynski@wavesoftware.pl">Krzysztof Suszynski</a>
+ * @since 2018-12-03
+ */
+public class InternalChecksTest {
+
+    @Rule
+    public ExpectedException expectedException = ExpectedException.none();
+
+    @Test
+    public void testCheckNotNull() {
+        // given
+        String eid = "20181203:223812";
+        String val = System.getProperty("non-existing-key-in-system");
+
+        // then
+        expectedException.expect(IllegalArgumentException.class);
+        expectedException.expectMessage(eid);
+
+        // when
+        InternalChecks.checkNotNull(val, eid);
+    }
+}

src/test/java/pl/wavesoftware/eid/impl/MessageSupplierTest.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2018 Wave Software
+ *
+ * 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 pl.wavesoftware.eid.impl;
+
+import org.junit.Test;
+import pl.wavesoftware.eid.configuration.Configuration;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author <a href="mailto:krzysztof.suszynski@wavesoftware.pl">Krzysztof Suszynski</a>
+ * @since 2018-12-03
+ */
+public class MessageSupplierTest {
+
+    @Test
+    public void testGet() {
+        // given
+        Configuration configuration = new ConfigurationImpl();
+        MessageSupplier supplier = new MessageSupplier(
+            configuration, "{0} -> 11", new Object[] { ".5" }
+        );
+
+        // when
+        String message = supplier.get();
+
+        // then
+        assertThat(message).isEqualTo(".5 -> 11");
+    }
+}