Merge branch '__rultor'

src/main/java/org/cactoos/Scalar.java

@@ -54,4 +54,41 @@ public interface Scalar<T> {
      */
     T value() throws Exception;
 
+    /**
+     * Scalar check for no nulls.
+     *
+     * @author Fabricio Cabral (fabriciofx@gmail.com)
+     * @version $Id$
+     * @param <T> Type of result
+     * @since 0.11
+     */
+    final class NoNulls<T> implements Scalar<T> {
+        /**
+         * The scalar.
+         */
+        private final Scalar<T> origin;
+        /**
+         * Ctor.
+         * @param sclr The scalar
+         */
+        public NoNulls(final Scalar<T> sclr) {
+            this.origin = sclr;
+        }
+        @Override
+        public T value() throws Exception {
+            if (this.origin == null) {
+                throw new IllegalArgumentException(
+                    "NULL instead of a valid scalar"
+                );
+            }
+            final T value = this.origin.value();
+            if (value == null) {
+                throw new IllegalStateException(
+                    "NULL instead of a valid value"
+                );
+            }
+            return value;
+        }
+    }
+
 }

src/test/java/org/cactoos/ScalarTest.java

@@ -0,0 +1,51 @@
+/**
+ * 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;
+
+import org.junit.Test;
+
+/**
+ * Test case for {@link Scalar.NoNulls}.
+ * @author Fabricio Cabral (fabriciofx@gmail.com)
+ * @version $Id$
+ * @since 0.11
+ * @checkstyle JavadocMethodCheck (500 lines)
+ */
+public final class ScalarTest {
+
+    @Test(expected = IllegalArgumentException.class)
+    public void failForNullArgument() throws Exception {
+        new Scalar.NoNulls<>(null).value();
+    }
+
+    @Test(expected = IllegalStateException.class)
+    public void failForNullResult() throws Exception {
+        new Scalar.NoNulls<>(() -> null).value();
+    }
+
+    @Test
+    public void okForNoNulls() throws Exception {
+        new Scalar.NoNulls<>(() -> 1).value();
+    }
+}