Add a function/some tests for string to nanocoin conversions and vice-versa, along with a TODO to clean this whole thing up. Patch from Thilo Planz.

Fixes issue 1.

tests/com/google/bitcoin/core/UtilsTest.java

@@ -0,0 +1,46 @@
+/**
+ * Copyright 2011 Thilo Planz
+ *
+ * Licensed 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.google.bitcoin.core;
+
+import static junit.framework.Assert.assertEquals;
+import static junit.framework.Assert.fail;
+
+import org.junit.Test;
+
+public class UtilsTest {
+
+    @Test
+    public void testToNanoCoins() {
+        // String version
+        assertEquals(Utils.CENT, Utils.toNanoCoins("0.01"));
+        assertEquals(Utils.CENT, Utils.toNanoCoins("1E-2"));
+        assertEquals(Utils.COIN.add(Utils.CENT), Utils.toNanoCoins("1.01"));
+        try {
+            Utils.toNanoCoins("2E-20");
+            fail("should not have accepted fractional nanocoins");
+        } catch (ArithmeticException e) {
+        }
+
+        // int version
+        assertEquals(Utils.CENT, Utils.toNanoCoins(0, 1));
+
+        // TODO: should this really pass?
+        assertEquals(Utils.COIN.subtract(Utils.CENT), Utils.toNanoCoins(1, -1));
+        assertEquals(Utils.COIN.negate(), Utils.toNanoCoins(-1, 0));
+        assertEquals(Utils.COIN.negate(), Utils.toNanoCoins("-1"));
+    }
+}