DATAKV-136 - Choose SecureRandom algorithm based on operating system and availability.

We now distinguish between operating systems when choosing a SecureRandom algorithm. Additionally we check the availability of the implementations and choose the first one available.

Original pull request: #21.

src/test/java/org/springframework/data/keyvalue/core/DefaultIdentifierGeneratorUnitTests.java

@@ -0,0 +1,92 @@
+/*
+ * Copyright 2016 the original author or authors.
+ *
+ * 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 org.springframework.data.keyvalue.core;
+
+import static org.hamcrest.core.Is.*;
+import static org.hamcrest.core.IsInstanceOf.*;
+import static org.hamcrest.core.IsNull.*;
+import static org.junit.Assert.*;
+
+import java.util.Date;
+import java.util.UUID;
+
+import org.junit.Test;
+import org.springframework.dao.InvalidDataAccessApiUsageException;
+import org.springframework.data.util.ClassTypeInformation;
+
+/**
+ * @author Christoph Strobl
+ */
+public class DefaultIdentifierGeneratorUnitTests {
+
+	DefaultIdentifierGenerator generator = DefaultIdentifierGenerator.INSTANCE;
+
+	/**
+	 * @DATAKV-136
+	 */
+	@Test(expected = InvalidDataAccessApiUsageException.class)
+	public void shouldThrowExceptionForUnsupportedType() {
+		generator.generateIdentifierOfType(ClassTypeInformation.from(Date.class));
+	}
+
+	/**
+	 * @DATAKV-136
+	 */
+	@Test
+	public void shouldGenerateUUIDValueCorrectly() {
+
+		Object value = generator.generateIdentifierOfType(ClassTypeInformation.from(UUID.class));
+
+		assertThat(value, is(notNullValue()));
+		assertThat(value, instanceOf(UUID.class));
+	}
+
+	/**
+	 * @DATAKV-136
+	 */
+	@Test
+	public void shouldGenerateStringValueCorrectly() {
+
+		Object value = generator.generateIdentifierOfType(ClassTypeInformation.from(String.class));
+
+		assertThat(value, is(notNullValue()));
+		assertThat(value, instanceOf(String.class));
+	}
+
+	/**
+	 * @DATAKV-136
+	 */
+	@Test
+	public void shouldGenerateLongValueCorrectly() {
+
+		Object value = generator.generateIdentifierOfType(ClassTypeInformation.from(Long.class));
+
+		assertThat(value, is(notNullValue()));
+		assertThat(value, instanceOf(Long.class));
+	}
+
+	/**
+	 * @DATAKV-136
+	 */
+	@Test
+	public void shouldGenerateIntValueCorrectly() {
+
+		Object value = generator.generateIdentifierOfType(ClassTypeInformation.from(Integer.class));
+
+		assertThat(value, is(notNullValue()));
+		assertThat(value, instanceOf(Integer.class));
+	}
+}