Removed obsolete testReadingTruncatedDataFile (#565)

This test does not throw the `IllegalBlockSizeException` on newer
versions of Android, instead the decrypted content is incomplete. There
doesn't seem to be any value in testing this underlying OS behaviour.

Author: ricellis

cloudant-sync-datastore-core/src/test/java/com/cloudant/sync/datastore/encryption/EncryptedAttachmentInputStreamTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2015 IBM Corp. All rights reserved.
+ * Copyright © 2015, 2018 IBM Corp. All rights reserved.
  *
  * 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
@@ -15,13 +15,12 @@
 package com.cloudant.sync.datastore.encryption;
 
 import com.cloudant.sync.internal.documentstore.encryption.EncryptedAttachmentInputStream;
-import com.cloudant.sync.matcher.CauseMatcher;
 import com.cloudant.sync.util.TestUtils;
 
 import org.apache.commons.io.IOUtils;
+import org.junit.Assert;
 import org.junit.Rule;
 import org.junit.Test;
-import org.junit.Assert;
 import org.junit.rules.ExpectedException;
 
 import java.io.File;
@@ -30,8 +29,6 @@
 import java.io.InputStream;
 import java.security.InvalidKeyException;
 
-import javax.crypto.IllegalBlockSizeException;
-
 /**
  * Test encrypting an attachment to check correct on disk format is read.
  */
@@ -86,25 +83,6 @@ public void testReadingTruncatedIVFile() throws IOException, InvalidKeyException
                 new FileInputStream(encryptedAttachmentBlob), EncryptionTestConstants.key16Byte);
     }
 
-    /**
-     * Test when we read file shorter than block multiple that an IOException escapes.
-     */
-    @Test
-    public void testReadingTruncatedDataFile() throws IOException, InvalidKeyException {
-        exception.expect(IOException.class);
-        exception.expectCause(new CauseMatcher(IllegalBlockSizeException.class));
-
-        File encryptedAttachmentBlob = TestUtils.loadFixture(
-                "fixture/EncryptedAttachmentTest_truncatedData");
-        InputStream encryptedInputStream = new EncryptedAttachmentInputStream(
-                new FileInputStream(encryptedAttachmentBlob), EncryptionTestConstants.key16Byte);
-
-        //noinspection StatementWithEmptyBody
-        while (encryptedInputStream.read(new byte[1024]) != -1) {
-            // just read the data
-        }
-    }
-
     @Test(expected=InvalidKeyException.class)
     public void Test31ByteKey() throws IOException, InvalidKeyException {
         new EncryptedAttachmentInputStream(null, EncryptionTestConstants.keyLength31);