#3: Not null text

src/main/java/org/cactoos/text/NotNullText.java

@@ -0,0 +1,60 @@
+/**
+ * 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.Text;
+
+/**
+ * A safe Text.
+ *
+ * <p>There is no thread-safety guarantee.
+ *
+ * @author Fabricio Cabral ([email protected])
+ * @version $Id$
+ * @since 0.2
+ */
+public final class NotNullText implements Text {
+
+    /**
+     * The text.
+     */
+    private final Text origin;
+
+    /**
+     * Ctor.
+     * @param text The text
+     */
+    public NotNullText(final Text text) {
+        this.origin = text;
+    }
+
+    @Override
+    public String asString() throws IOException {
+        if (this.origin == null) {
+            throw new IOException("invalid text (null)");
+        }
+        return this.origin.asString();
+    }
+}

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

@@ -0,0 +1,57 @@
+/**
+ * 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.TextHasString;
+import org.hamcrest.MatcherAssert;
+import org.junit.Test;
+
+/**
+ * Test case for {@link NotNullText}.
+ * @author Fabricio Cabral ([email protected])
+ * @version $Id$
+ * @since 0.2
+ * @checkstyle JavadocMethodCheck (500 lines)
+ */
+public final class NotNullTextTest {
+
+    @Test(expected = IOException.class)
+    public void failForNullText() throws IOException {
+        new NotNullText(null).asString();
+    }
+
+    @Test
+    public void checkForNullText() throws Exception {
+        final String message = "Hello";
+        MatcherAssert.assertThat(
+            "Can't work with null text",
+            new NotNullText(
+                new StringAsText(message)
+            ),
+            new TextHasString(message)
+        );
+    }
+
+}