*: Add testfork.RunTest to run multiple tests in one function

[lcwangchao]

What problem does this PR solve?

Issue Number: close #35747

What is changed and how it works?

Some times we want to do a series of tests and all the them are similar except for some parameters. For example:

	for _, autocommit := range []bool{false, true} {
		for _, isolation := range []string{"READ-COMMITTED", "REPEATABLE-READ"} {
			t.Run("", func(t *testing.T) {
				tk := testkit.NewTestKit(t, store)
				tk.MustExec(fmt.Sprintf("set tx_isolation = '%s'", isolation)
				tk.MustExec(fmt.Sprintf("set autocommit=%d", autocommit))
				tk.MustExec("insert into t values(1, 2)")
				tk.MustQuery("select * from t where id=1").Check(testkit.Rows("1 2"))
			})
		}
	}

The above test will generate 4 sub tests and each of them will test one combination of isolation and autcommit settings. However, the implement is very elegant because the "for loops" are nested. When we have more and more parameters to composite, we will get a very deep syntax tree.

This PR provide a new method testfork.RunTest to simplify the above cases, for example, the above test codes can be like this:

	testfork.RunTest(t, func(t *testfork.T) {
		tk := testkit.NewTestKit(t, store)
		isolation := testfork.PickEnum(t, "READ-COMMITTED", "REPEATABLE-READ")
		tk.MustExec(fmt.Sprintf("set tx_isolation = '%s'", isolation))
		autocommit := testfork.PickEnum(t, 1, 0)
		tk.MustExec(fmt.Sprintf("set autocommit=%d", autocommit))
		tk.MustExec("insert into t values(1, 2)")
		tk.MustQuery("select * from t where id=1").Check(testkit.Rows("1 2"))
	})

When we call Pick or PickEnum in a function, the test will "fork" to several sub tests according to the candidate values passed to it. Pick or PickEnum can be called multiple times in a function, and it will "fork" multiple times if you do it.

It also support conditional fork, for example:

	testfork.RunTest(t, func(t *testfork.T) {
		tk := testkit.NewTestKit(t, store)
		if pessimistic := testfork.PickEnum(t, true, false); pessimistic {
			isolation := testfork.PickEnum(t, "READ-COMMITTED", "REPEATABLE-READ")
			tk.MustExec(fmt.Sprintf("set tx_isolation = '%s'", isolation))
		}

		autocommit := testfork.PickEnum(t, 1, 0)
		tk.MustExec(fmt.Sprintf("set autocommit=%d", autocommit))
		tk.MustExec("insert into t values(1, 2)")
		tk.MustQuery("select * from t where id=1").Check(testkit.Rows("1 2"))
	})

In the above demo tx_siolation will only be forked and set when pessimistic is true (it is also a forked value and can be different in different sub tests).

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• bb7133
• tiancaiamao

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[sre-bot]

Please follow PR Title Format:

• pkg [, pkg2, pkg3]: what is changed

Or if the count of mainly changed packages are more than 3, use

• *: what is changed

After you have format title, you can leave a comment /run-check_title to recheck it

[sre-bot]

Code Coverage Details: https://codecov.io/github/pingcap/tidb/commit/59d51e2487ffc9a5d2c628756b27114210843750

[tiancaiamao]

You code make me think of a old joke:
"what's the biggest hinder that prevent functional programming language from being popular?"
The answer is:
"we don't get enough "clever" programmers. That's the biggest hinder and it's insoluble."

The code itself is clever, but I can't claim this developing philosophy as wise.
Stupid simple code is the real wisdom for the averages.

[lcwangchao]

You code make me think of a old joke:

"what's the biggest hinder that prevent functional programming language from being popular?"
The answer is:
"we don't get enough "clever" programmers. That's the biggest hinder and it's insoluble."
The code itself is clever, but I can't claim this developing philosophy as wise. Stupid simple code is the real wisdom for the averages.

I agree with you with some of the opinions. But I think the key point is "only use it when it is necessary". "Necessary" means it can reduce the implement complex a lot when use it. I don't think it's a good practice to apply the FP to the whole project, but they can work better in some certain cases for example: react UI. Whether to use it or not can be determined by the developer.

[bb7133]

LGTM

[bb7133]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 374bee1

[lcwangchao]

/rebuild

[lcwangchao]

/rebuild

[lcwangchao]

/run-check_dev_2

[lcwangchao]

/run-mysql-test

[sre-bot]

TiDB MergeCI notify

🔴 Bad News! New failing [1] after this pr merged.
These new failed integration tests seem to be caused by the current PR, please try to fix these new failed integration tests, thanks!

CI Name	Result	Duration	Compare with Parent commit
idc-jenkins-ci-tidb/integration-ddl-test	🟥 failed 1, success 5, total 6	14 min	New failing
idc-jenkins-ci-tidb/integration-common-test	🔴 failed 2, success 9, total 11	27 min	Existing failure
idc-jenkins-ci-tidb/common-test	✅ all 12 tests passed	9 min 33 sec	Fixed
idc-jenkins-ci/integration-cdc-test	🟢 all 35 tests passed	30 min	Existing passed
idc-jenkins-ci-tidb/sqllogic-test-2	🟢 all 28 tests passed	7 min 32 sec	Existing passed
idc-jenkins-ci-tidb/sqllogic-test-1	🟢 all 26 tests passed	6 min 52 sec	Existing passed
idc-jenkins-ci-tidb/tics-test	🟢 all 1 tests passed	6 min 6 sec	Existing passed
idc-jenkins-ci-tidb/integration-compatibility-test	🟢 all 1 tests passed	3 min 33 sec	Existing passed
idc-jenkins-ci-tidb/mybatis-test	🟢 all 1 tests passed	2 min 52 sec	Existing passed
idc-jenkins-ci-tidb/plugin-test	🟢 build success, plugin test success	4min	Existing passed