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/cc @tisonkun
hi, please help review, thanks

@feitian124 thanks for your contribution @feitian124 ! I'll review this PR tomorrow.

@tisonkun ok, thanks

sorry, it is large and take me some time to finish...
but i am not sure how to separate them to 2 pr as they solve 1 issue， and if put them in 2 different branch the unit test will fail without aditional work.

i did reorder my commit and pushed to a new branch https://github.com/feitian124/tidb/commits/issue-26420-new,
so statement_summary_test.go is in an separate commit.

commit f01914e8ecf743b3a22edf81a49ed25eb9ac6c7d (HEAD -> issue-26420-new, my/issue-26420-new, issue-26420-part1)
Author: feitian124 <feitian124@gmail.com>
Date:   Tue Aug 3 13:32:11 2021 +0800

    util/stmtsummary: migrate test-infra to testify, part 2

 util/stmtsummary/evicted_test.go   | 143 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-------------------------------------------------------------------
 util/stmtsummary/main_test.go      |  26 ++++++++++++++++++++++++++
 util/stmtsummary/variables_test.go |  98 +++++++++++++++++++++++++++++++++++++++++++++++++-------------------------------------------------
 3 files changed, 151 insertions(+), 116 deletions(-)

commit 68a3829fefe77aa229af61963710366bfe452120
Author: feitian124 <feitian124@gmail.com>
Date:   Tue Aug 3 13:32:00 2021 +0800

    util/stmtsummary: migrate test-infra to testify, part 1

 util/stmtsummary/statement_summary_test.go | 615 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-------------------------------------------------------------------------------------------
 1 file changed, 311 insertions(+), 304 deletions(-)

not sure if this help.
if this is what you want, i can create a new pr based on issue-26420-new and close this pr.
if this is not what you want, please give some guide.
thanks.

@feitian124 you can take a look at how we do it for domain pkg #26306, or if you separate in multiple commits in one PR said this one, it is fine also.

Here is an example how to break diff into meaningful commits that helps on reviewing. https://github.com/apache/flink/pull/9832/commits

@feitian124 you can take a look at how we do it for domain pkg #26306, or if you separate in multiple commits in one PR said this one, it is fine also.

hi @tisonkun , i have separate them to 3 pr, hopefully can make your review easier.