Added tests to point out areas for improvements with next refactoring.

Improved coverage a little as aside-effect.

src/test/java/org/torproject/collector/bridgedescs/BridgeDescriptorParserTest.java

@@ -0,0 +1,48 @@
+/* Copyright 2016 The Tor Project
+ * See LICENSE for licensing information */
+
+package org.torproject.collector.bridgedescs;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
+import org.torproject.collector.conf.Configuration;
+
+import org.junit.Test;
+
+public class BridgeDescriptorParserTest {
+
+  @Test(expected = IllegalArgumentException.class)
+  public void testNullArgForConstructor() throws Exception {
+    new BridgeDescriptorParser(null);
+  }
+
+  @Test(expected = NullPointerException.class)
+  public void testNullData() throws Exception {
+    BridgeDescriptorParser bdp = new BridgeDescriptorParser(
+        new SanitizedBridgesWriter(new Configuration()));
+    bdp.parse(null, "", "");
+  }
+
+  @Test
+  /* Empty data is not passed down to the sanitized writer.
+   * This test passes when there is no exception. */
+  public void testDataEmpty() throws Exception {
+    BridgeDescriptorParser bdp = new BridgeDescriptorParser(
+        new SanitizedBridgesWriter(new Configuration()));
+    bdp.parse(new byte[]{}, null, null);
+  }
+
+  @Test(expected = NullPointerException.class)
+  /* The SanitizedBridgesWriter wasn't initialized sufficiently.
+   * Actually that should be corrected in SanitizedBridgesWriter
+   * at some point, but that's a bigger rewrite. */
+  public void testMinimalData() throws Exception {
+    BridgeDescriptorParser bdp = new BridgeDescriptorParser(
+        new SanitizedBridgesWriter(new Configuration()));
+    bdp.parse(new byte[]{0}, "2010-10-10 10:10:10", null);
+  }
+
+}