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From "Tsz Wo Nicholas Sze (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-7738) Add more negative tests for truncate
Date Fri, 06 Feb 2015 20:20:37 GMT

    [ https://issues.apache.org/jira/browse/HDFS-7738?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14309818#comment-14309818

Tsz Wo Nicholas Sze commented on HDFS-7738:

> In general I don't like random tests because they imply intermittent failures, ...

If there are intermittent failures, it means that there are bugs either in the code or in
the test.  I guess what you don't like is poorly written random tests which may experience
intermittent failures.  For well written tests, it won't have intermittent failures.

Why we need random tests?  It is because the problem space is huge so that it is impossible
to try all the cases.  We have to do random sampling.

testBasicTruncate, which is a well written test, does cover a lot of cases.  However, it only
tests a 12 bytes file with 3 blocks.  Also, toTruncate is consecutive.  For example, it does
not test the case calling truncate to take out 10 blocks at once.

> Add more negative tests for truncate
> ------------------------------------
>                 Key: HDFS-7738
>                 URL: https://issues.apache.org/jira/browse/HDFS-7738
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>          Components: test
>            Reporter: Tsz Wo Nicholas Sze
>            Assignee: Tsz Wo Nicholas Sze
>            Priority: Minor
>             Fix For: 2.7.0
>         Attachments: h7738_20150204.patch, h7738_20150205.patch, h7738_20150205b.patch,
> The following are negative test cases for truncate.
> - new length > old length
> - truncating a directory
> - truncating a non-existing file
> - truncating a file without write permission
> - truncating a file opened for append
> - truncating a file in safemode

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