yegor256#278 NoNulls for Text

src/main/java/org/cactoos/Text.java

@@ -24,6 +24,7 @@
 package org.cactoos;
 
 import java.io.IOException;
+import org.cactoos.text.UncheckedText;
 
 /**
  * Text.
@@ -44,4 +45,47 @@ public interface Text extends Comparable<Text> {
      */
     String asString() throws IOException;
 
+    /**
+     * Text check for no nulls.
+     *
+     * <p>There is no thread-safety guarantee.
+     *
+     * @author Fabricio Cabral (fabriciofx@gmail.com)
+     * @version $Id$
+     * @since 0.11
+     */
+    final class NoNulls implements Text {
+        /**
+         * The origin text.
+         */
+        private final Text origin;
+        /**
+         * Ctor.
+         * @param text The text
+         */
+        public NoNulls(final Text text) {
+            this.origin = text;
+        }
+        @Override
+        public String asString() throws IOException {
+            if (this.origin == null) {
+                throw new IOException("NULL instead of a valid text");
+            }
+            final String string = this.origin.asString();
+            if (string == null) {
+                throw new IOException("NULL instead of a valid result string");
+            }
+            return string;
+        }
+        @Override
+        public int compareTo(final Text text) {
+            if (text == null) {
+                throw new IllegalArgumentException(
+                    "NULL parameter instead of a valid text"
+                );
+            }
+            return new UncheckedText(this).compareTo(text);
+        }
+    }
+
 }

src/test/java/org/cactoos/text/NotNullTextTest.java → src/test/java/org/cactoos/TextTest.java

@@ -21,33 +21,49 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package org.cactoos.text;
+package org.cactoos;
 
 import java.io.IOException;
-import org.cactoos.TextHasString;
+import org.cactoos.text.StringAsText;
 import org.hamcrest.MatcherAssert;
 import org.junit.Test;
 
 /**
- * Test case for {@link NotNullText}.
+ * Test case for {@link Text}.
  * @author Fabricio Cabral (fabriciofx@gmail.com)
  * @version $Id$
- * @since 0.3
+ * @since 0.11
  * @checkstyle JavadocMethodCheck (500 lines)
  */
-public final class NotNullTextTest {
+public final class TextTest {
 
     @Test(expected = IOException.class)
     public void failForNullText() throws IOException {
-        new NotNullText(null).asString();
+        new Text.NoNulls(null).asString();
+    }
+
+    @Test(expected = IOException.class)
+    public void failForReturnNullString() throws IOException {
+        new Text.NoNulls(
+            new Text() {
+                @Override
+                public String asString() throws IOException {
+                    return null;
+                }
+                @Override
+                public int compareTo(final Text text) {
+                    return 0;
+                }
+            }
+        ).asString();
     }
 
     @Test
     public void checkForNullText() throws Exception {
         final String message = "Hello";
         MatcherAssert.assertThat(
             "Can't work with null text",
-            new NotNullText(
+            new Text.NoNulls(
                 new StringAsText(message)
             ),
             new TextHasString(message)