*:move explain_test to tidb repository (pingcap#6555)

.gitignore

@@ -13,3 +13,4 @@ tags
 temp_parser_file
 y.output
 profile.coverprofile
+explain_test

Makefile

@@ -106,7 +106,10 @@ todo:
 	@grep -n BUG */*.go parser/parser.y || true
 	@grep -n println */*.go parser/parser.y || true
 
-test: checklist gotest
+test: checklist gotest explaintest
+
+explaintest: server
+	@cd cmd/explaintest && ./run-tests.sh -s ../../bin/tidb-server
 
 gotest: parserlib
 	go get github.com/coreos/gofail
@@ -166,6 +169,7 @@ benchraw:
 
 benchdb:
 	$(GOBUILD) -ldflags '$(LDFLAGS)' -o bin/benchdb cmd/benchdb/main.go
+
 importer:
 	$(GOBUILD) -ldflags '$(LDFLAGS)' -o bin/importer ./cmd/importer
 

cmd/explaintest/README.md

@@ -0,0 +1,65 @@
+# ExplainTest
+
+ExplainTest is a explain test command tool, also with some useful test cases for TiDB execute plan logic, we can run case via `run-tests.sh`.
+
+```
+Usage: ./run-tests.sh [options]
+
+    -h: Print this help message.
+
+    -s <tidb-server-path>: Use tidb-server in <tidb-server-path> for testing.
+                           eg. "./run-tests.sh -s ./explaintest_tidb-server"
+
+    -b <y|Y|n|N>: "y" or "Y" for building test binaries [default "y" if this option is not specified].
+                  "n" or "N" for not to build.
+                  The building of tidb-server will be skiped if "-s <tidb-server-path>" is provided.
+
+    -r <test-name>|all: Run tests in file "t/<test-name>.test" and record result to file "r/<test-name>.result".
+                        "all" for running all tests and record their results.
+
+    -t <test-name>: Run tests in file "t/<test-name>.test".
+                    This option will be ignored if "-r <test-name>" is provided.
+                    Run all tests if this option is not provided.
+
+    -v <vendor-path>: Add <vendor-path> to $GOPATH.
+
+    -c <test-name>|all: Create data according to creating statements in file "t/<test-name>.test" and save stats in "s/<test-name>_tableName.json".
+                    <test-name> must has a suffix of '_stats'.
+                    "all" for creating stats of all tests.
+
+    -i <importer-path>: Use importer in <importer-path> for creating data.
+```
+
+## How it works
+
+ExplainTest will read test case in `t/*.test`, and execute them in TiDB server with `s/*.json` stat, and compare explain result in `r/*.result`.
+
+For convenience, we can generate new `*.result` and `*.json` from execute by use `-r` parameter for `run-tests.sh`
+
+## Usage
+
+### Regression Execute Plan Modification
+
+After modify code and before commit, please run this command under TiDB root folder.
+
+```sh
+make dev
+```
+
+or
+
+```sh
+make explaintest
+```
+It will identify execute plan change.
+
+### Generate New Stats and Result from Execute
+
+First, add new test query in `t/` folder.
+
+```sh
+cd cmd/explaintest
+./run-tests.sh -r [casename]
+./run-tests.sh -c [casename]
+``
+It will generate result and stats base on last execution, and then we can reuse them or open editor to do some modify.

cmd/explaintest/_helper.sh

@@ -0,0 +1,31 @@
+#!/bin/bash
+# set -ueax
+# when you want to debug, please uncomment the above line and comment the following line.
+set -uea
+
+OLD_GOPATH=$GOPATH
+PINGCAP_PATH="$(dirname $PWD)"
+while [ "$(basename $PINGCAP_PATH)" != "pingcap" ]; do
+    PINGCAP_PATH="$(dirname $PINGCAP_PATH)"
+done
+TIDB_VENDOR_PATH=$PINGCAP_PATH/tidb/vendor
+
+function prepare_env {
+    export GOPATH=$GOPATH:$TIDB_VENDOR_PATH
+}
+
+function recover_env {
+    export GOPATH=$OLD_GOPATH
+}
+
+function kill_proc_by_port() {
+    if [ ! -z $1 ]; then
+        kill $(lsof -t -i:$1)
+    else 
+        echo "please specify port number"
+    fi
+}
+
+set +uea
+trap 'set +e; PIDS=$(jobs -p); [ -n "$PIDS" ] && kill -9 $PIDS' EXIT
+

cmd/explaintest/config.toml

@@ -0,0 +1,11 @@
+port = 4001
+lease = "0"
+
+[log]
+level = "error"
+
+[status]
+status-port = 10081
+
+[performance]
+stats-lease = "0"