linter: add too much test checker (#45434)

ref pingcap/tidb#44940

build/BUILD.bazel

@@ -161,6 +161,7 @@ nogo(
                "//build/linter/predeclared",
                "//build/linter/unconvert",
                "//build/linter/rowserrcheck",
+               "//build/linter/toomanytests",
            ] + staticcheck_analyzers(STATICHECK_ANALYZERS) +
            select({
                "//build:with_nogo": [

build/linter/toomanytests/BUILD.bazel

@@ -0,0 +1,9 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
+
+go_library(
+    name = "toomanytests",
+    srcs = ["analyze.go"],
+    importpath = "github.com/pingcap/tidb/build/linter/toomanytests",
+    visibility = ["//visibility:public"],
+    deps = ["@org_golang_x_tools//go/analysis"],
+)

build/linter/toomanytests/analyze.go

@@ -0,0 +1,47 @@
+// Copyright 2023 PingCAP, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package toomanytests
+
+import (
+	"go/ast"
+	"strings"
+
+	"golang.org/x/tools/go/analysis"
+)
+
+// Analyzer is the analyzer struct of toomanytests
+var Analyzer = &analysis.Analyzer{
+	Name: "toomanytests",
+	Doc:  "too many tests in the package",
+	Run: func(pass *analysis.Pass) (any, error) {
+		cnt := 0
+		for _, f := range pass.Files {
+			for _, n := range f.Decls {
+				funcDecl, ok := n.(*ast.FuncDecl)
+				if ok {
+					if strings.HasPrefix(funcDecl.Name.Name, "Test") && funcDecl.Recv == nil &&
+						funcDecl.Name.Name != "TestMain" {
+						cnt++
+					}
+				}
+			}
+			if cnt > 50 {
+				pass.Reportf(f.Pos(), "%s: Too many test cases in one package", pass.Pkg.Name())
+				return nil, nil
+			}
+		}
+		return nil, nil
+	},
+}

build/nogo_config.json

@@ -585,6 +585,23 @@
       ".*_generated\\.go$": "ignore generated code"
     }
   },
+  "toomanytests": {
+    "exclude_files": {
+      "parser/parser.go": "parser/parser.go code",
+      "external/": "no need to vet third party code",
+      ".*_generated\\.go$": "ignore generated code",
+      "/cgo/": "ignore cgo code",
+      "/rules_go_work-*": "ignore generated code",
+      ".*test_/testmain\\.go$": "ignore generated code",
+      ".*failpoint_binding__.go$": "ignore generated code",
+      "util/chunk": "ignore util/chunk"
+    },
+    "only_files": {
+      "disttask/": "disttask code",
+      "timer/": "timer code",
+      "util/": "util code"
+    }
+  },
   "unconvert": {
     "exclude_files": {
       "external/": "no need to vet third party code",