diff -r 000000000000 -r 6474c204b198 mobile/android/tests/background/junit3/src/healthreport/TestEnvironmentV1HashAppender.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mobile/android/tests/background/junit3/src/healthreport/TestEnvironmentV1HashAppender.java	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,146 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+package org.mozilla.gecko.background.healthreport;
+
+import java.io.UnsupportedEncodingException;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.util.Arrays;
+import java.util.LinkedList;
+
+import org.mozilla.apache.commons.codec.binary.Base64;
+import org.mozilla.gecko.background.healthreport.EnvironmentV1.EnvironmentAppender;
+import org.mozilla.gecko.background.healthreport.EnvironmentV1.HashAppender;
+import org.mozilla.gecko.background.helpers.FakeProfileTestCase;
+import org.mozilla.gecko.sync.Utils;
+
+/**
+ * Tests the HashAppender functionality. Note that these tests must be run on an Android
+ * device because the SHA-1 native library needs to be loaded.
+ */
+public class TestEnvironmentV1HashAppender extends FakeProfileTestCase {
+  // input and expected values via: http://oauth.googlecode.com/svn/code/c/liboauth/src/sha1.c
+  private final static String[] INPUTS = new String[] {
+    "abc",
+    "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq",
+    "" // To be filled in below.
+  };
+  static {
+    final String baseStr = "01234567";
+    final int repetitions = 80;
+    final StringBuilder builder = new StringBuilder(baseStr.length() * repetitions);
+    for (int i = 0; i < 80; ++i) {
+      builder.append(baseStr);
+    }
+    INPUTS[2] = builder.toString();
+  }
+
+  private final static String[] EXPECTEDS = new String[] {
+    "a9993e364706816aba3e25717850c26c9cd0d89d",
+    "84983e441c3bd26ebaae4aa1f95129e5e54670f1",
+    "dea356a2cddd90c7a7ecedc5ebb563934f460452"
+  };
+  static {
+    for (int i = 0; i < EXPECTEDS.length; ++i) {
+      EXPECTEDS[i] = new Base64(-1, null, false).encodeAsString(Utils.hex2Byte(EXPECTEDS[i]));
+    }
+  }
+
+  public void testSHA1Hashing() throws Exception {
+    for (int i = 0; i < INPUTS.length; ++i) {
+      final String input = INPUTS[i];
+      final String expected = EXPECTEDS[i];
+
+      final HashAppender appender = new HashAppender();
+      addStringToAppenderInParts(appender, input);
+      final String result = appender.toString();
+
+      assertEquals(expected, result);
+    }
+  }
+
+  /**
+   * Tests to ensure output is the same as the former MessageDigest implementation (bug 959652).
+   */
+  public void testAgainstMessageDigestImpl() throws Exception {
+    // List.add doesn't allow add(null) so we make a LinkedList here.
+    final LinkedList<String> inputs = new LinkedList<String>(Arrays.asList(INPUTS));
+    inputs.add(null);
+
+    for (final String input : inputs) {
+      final HashAppender hAppender = new HashAppender();
+      final MessageDigestHashAppender mdAppender = new MessageDigestHashAppender();
+
+      hAppender.append(input);
+      mdAppender.append(input);
+
+      final String hResult = hAppender.toString();
+      final String mdResult = mdAppender.toString();
+      assertEquals(mdResult, hResult);
+    }
+  }
+
+  public void testIntegersAgainstMessageDigestImpl() throws Exception {
+    final int[] INPUTS = {Integer.MIN_VALUE, -1337, -42, 0, 42, 1337, Integer.MAX_VALUE};
+    for (final int input : INPUTS) {
+      final HashAppender hAppender = new HashAppender();
+      final MessageDigestHashAppender mdAppender = new MessageDigestHashAppender();
+
+      hAppender.append(input);
+      mdAppender.append(input);
+
+      final String hResult = hAppender.toString();
+      final String mdResult = mdAppender.toString();
+      assertEquals(mdResult, hResult);
+    }
+  }
+
+  private void addStringToAppenderInParts(final EnvironmentAppender appender, final String input) {
+    int substrInd = 0;
+    int substrLength = 1;
+    while (substrInd < input.length()) {
+      final int endInd = Math.min(substrInd + substrLength, input.length());
+
+      appender.append(input.substring(substrInd, endInd));
+
+      substrInd = endInd;
+      ++substrLength;
+    }
+  }
+
+  // --- COPY-PASTA'D CODE, FOR TESTING PURPOSES. ---
+  public static class MessageDigestHashAppender extends EnvironmentAppender {
+    final MessageDigest hasher;
+
+    public MessageDigestHashAppender() throws NoSuchAlgorithmException {
+      // Note to the security-minded reader: we deliberately use SHA-1 here, not
+      // a stronger hash. These identifiers don't strictly need a cryptographic
+      // hash function, because there is negligible value in attacking the hash.
+      // We use SHA-1 because it's *shorter* -- the exact same reason that Git
+      // chose SHA-1.
+      hasher = MessageDigest.getInstance("SHA-1");
+    }
+
+    @Override
+    public void append(String s) {
+      try {
+        hasher.update(((s == null) ? "null" : s).getBytes("UTF-8"));
+      } catch (UnsupportedEncodingException e) {
+        // This can never occur. Thanks, Java.
+      }
+    }
+
+    @Override
+    public void append(int profileCreation) {
+      append(Integer.toString(profileCreation, 10));
+    }
+
+    @Override
+    public String toString() {
+      // We *could* use ASCII85… but the savings would be negated by the
+      // inclusion of JSON-unsafe characters like double-quote.
+      return new Base64(-1, null, false).encodeAsString(hasher.digest());
+    }
+  }
+}