#3: Not null output

src/main/java/org/cactoos/io/NotNullOutput.java

@@ -0,0 +1,62 @@
+/**
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 Yegor Bugayenko
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package org.cactoos.io;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import org.cactoos.Output;
+
+/**
+ * A safe Output.
+ *
+ * <p>There is no thread-safety guarantee.
+ *
+ * @author Fabricio Cabral ([email protected])
+ * @version $Id$
+ * @since 0.2
+ */
+public final class NotNullOutput implements Output {
+
+    /**
+     * The output.
+     */
+    private final Output origin;
+
+    /**
+     * Ctor.
+     * @param output The output
+     */
+    public NotNullOutput(final Output output) {
+        this.origin = output;
+    }
+
+    @Override
+    public OutputStream stream() throws IOException {
+        if (this.origin == null) {
+            throw new IOException("invalid output (null)");
+        }
+        return this.origin.stream();
+    }
+
+}

src/test/java/org/cactoos/text/NotNullOutputTest.java

@@ -0,0 +1,45 @@
+/**
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 Yegor Bugayenko
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package org.cactoos.text;
+
+import java.io.IOException;
+import org.cactoos.io.NotNullInput;
+import org.cactoos.io.NotNullOutput;
+import org.junit.Test;
+
+/**
+ * Test case for {@link NotNullInput}.
+ * @author Fabricio Cabral ([email protected])
+ * @version $Id$
+ * @since 0.2
+ * @checkstyle JavadocMethodCheck (500 lines)
+ */
+public final class NotNullOutputTest {
+
+    @Test(expected = IOException.class)
+    public void failForNullOutput() throws IOException {
+        new NotNullOutput(null).stream();
+    }
+
+}