testutil: When there is // in the json test data, the test framework will report an error.

[LittleFall]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

change any testdata json file , add // in it, just like:

      {
        "SQL": "EXPLAIN SELECT * from t join s; -- FIXME: there is some bug on it, see https://github.com/pingcap/tidb/issues/26249",
        "Plan": [
          "HashJoin_8 100000000.00 root  CARTESIAN inner join",
          "├─TableReader_17(Build) 10000.00 root  data:TableFullScan_16",
          "│ └─TableFullScan_16 10000.00 cop[tiflash] table:s keep order:false, stats:pseudo",
          "└─TableReader_13(Probe) 10000.00 root  data:TableFullScan_12",
          "  └─TableFullScan_12 10000.00 cop[tiflash] table:t keep order:false, stats:pseudo"
        ],
        "Warn": [
          "MPP mode may be blocked because `Cartesian Product` is only supported by broadcast join, check value and documents of variables `tidb_opt_broadcast_cartesian_join`, `tidb_broadcast_join_threshold_size` and `tidb_broadcast_join_threshold_count`.",
          "MPP mode may be blocked because `Cartesian Product` is only supported by broadcast join, check value and documents of variables `tidb_opt_broadcast_cartesian_join`, `tidb_broadcast_join_threshold_size` and `tidb_broadcast_join_threshold_count`."
        ]
      },

add run this test:

/usr/local/Cellar/go/1.16.3/libexec/bin/go test -v ./planner/core/... -check.f TestEnforceMPP.* -check.vv

2. What did you expect to see? (Required)

test pass.

3. What did you see instead (Required)

c.Assert(err, IsNil)
Expected :
Actual   :*json.SyntaxError = &json.SyntaxError{msg:"invalid character 'P' after object key:value pair", Offset:30264} ("invalid character 'P' after object key:value pair")

4. What is your TiDB version? (Required)

20210714 master

https://github.com/pingcap/tidb/tree/737fa5b743c365e6bd7a7c30c54f9cb299b01e8d

[LittleFall]

this may because tidb wants to ignore the comment in json.

[LittleFall]

It seems that this is not a planner issue? I take the test in the planner as an example, but other tests may also have this problem.

[jyz0309]

I have checked the code, and seem it is the normal behavior?

tidb/util/testutil/testutil.go

Line 294 in a6326cc

// Remove comments, since they are not allowed in json.

[LittleFall]

I have checked the code, and seem it is the normal behavior?

tidb/util/testutil/testutil.go

Line 294 in a6326cc

// Remove comments, since they are not allowed in json.

I have seen it too, but I think it is unreasonable, tidb introduced a bug (we can't type // in json) for an unnecessary feature (support comments in json).

Or maybe we can find a way to support them both, such as a better parser.

[yudongusa]

transfer this ticket to parser/sql_infra team for further enhancement.