fix human readable formatter for negative sizes, zero bytes, and one …

…byte

pom.xml

@@ -69,6 +69,11 @@
       <artifactId>picocli</artifactId>
       <scope>compile</scope>
     </dependency>
+    <dependency>
+      <groupId>junit</groupId>
+      <artifactId>junit</artifactId>
+      <scope>test</scope>
+    </dependency>
     <dependency>
       <groupId>org.slf4j</groupId>
       <artifactId>slf4j-simple</artifactId>

src/main/java/com/github/heuermh/cooper/HumanReadableFormatter.java

@@ -48,11 +48,20 @@ final class HumanReadableFormatter {
      * Format the specified size in bytes to human readable
      * binary multi-byte units.
      *
-     * @param size, size in bytes
+     * @param size, size in bytes, must be at least zero
      * @return the specified size in bytes formatted to human readable
      *    binary multi-byte units
      */
     String format(final long size) {
+        if (size < 0L) {
+            throw new IllegalArgumentException("size must be at least zero");
+        }
+        if (size == 0L) {
+            return "0 Bytes";
+        }
+        if (size == 1L) {
+            return "1 Byte";
+        }
         int digitGroups = (int) (Math.log10(size) / Math.log10(1024));
         return decimalFormat.format(size / Math.pow(1024, digitGroups)) + " " + UNITS[digitGroups];
     }

src/test/java/com/github/heuermh/cooper/HumanReadableFormatterTest.java

@@ -0,0 +1,44 @@
+/*
+ * The authors of this file license it to you 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 com.github.heuermh.cooper;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.Test;
+
+/**
+ * Unit test for HumanReadableFormatter.
+ *
+ * @author  Michael Heuer
+ */
+public final class HumanReadableFormatterTest {
+
+    @Test(expected=IllegalArgumentException.class)
+    public void testFormatLessThanZero() {
+        new HumanReadableFormatter().format(-1L);
+    }
+
+    @Test
+    public void testFormat() {
+        HumanReadableFormatter formatter = new HumanReadableFormatter();
+        assertEquals("0 Bytes", formatter.format(0L));
+        assertEquals("1 Byte", formatter.format(1L));
+        assertEquals("113 Bytes", formatter.format(113L));
+        assertEquals("2.1 KiB", formatter.format(2122L));
+        assertEquals("377.3 MiB", formatter.format(395610342L));
+        assertEquals("1.7 GiB", formatter.format(1826577054L));
+    }
+}