feat: allow to specify Go version

README.md

@@ -45,9 +45,9 @@ go vet -vettool=(which tenv) ./...
 ./main_test.go:11:2: os.Setenv() can be replaced by `t.Setenv()` in TestMain
 ```
 
-### option
+### options
 
-The option `all` will run against whole test files (`_test.go`) regardless of method/function signatures.  
+The option `all` will run against whole test files (`_test.go`) regardless of method/function signatures.
 
 By default, only methods that take `*testing.T`, `*testing.B`, and `testing.TB` as arguments are checked.
 
@@ -75,13 +75,20 @@ func helper() {
 ```
 
 ```console
-go vet -vettool=(which tenv) -tenv.all ./...
+go vet -vettool=$(which tenv) -tenv.all ./...
 
 # a
 ./main_test.go:11:2: os.Setenv() can be replaced by `t.Setenv()` in TestMain
 ./main_test.go:19:2: os.Setenv() can be replaced by `testing.Setenv()` in helper
 ```
 
+The option `go` allows to specify Go version. If the version is not empty or lower than Go 1.17, the analysis will be skipped.
+
+```console
+go vet -vettool=$(which tenv) -tenv.go 1.16 ./...
+
+Outputs nothing because specified Go 1.16 is lower than 1.17.
+
 ## CI
 
 ### CircleCI

tenv.go

@@ -1,7 +1,10 @@
 package tenv
 
 import (
+	"errors"
+	"fmt"
 	"go/ast"
+	"strconv"
 	"strings"
 
 	"golang.org/x/tools/go/analysis"
@@ -24,13 +27,27 @@ var Analyzer = &analysis.Analyzer{
 var (
 	A     = "all"
 	aflag bool
+
+	Go     = "go"
+	goflag string
 )
 
 func init() {
 	Analyzer.Flags.BoolVar(&aflag, A, false, "the all option will run against all method in test file")
+	Analyzer.Flags.StringVar(&goflag, Go, "1.17", "Go version")
 }
 
 func run(pass *analysis.Pass) (interface{}, error) {
+	lower, err := goVersionLower117(goflag)
+	if err != nil {
+		return nil, err
+	}
+
+	if lower {
+		// Do nothing because T.Setenv added in go1.17
+		return nil, nil
+	}
+
 	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
 
 	nodeFilter := []ast.Node{
@@ -211,3 +228,33 @@ func checkSelectorExprTarget(typ *ast.SelectorExpr) bool {
 	targetName := x.Name + "." + typ.Sel.Name
 	return targetName == "testing.TB"
 }
+
+// goVersionLower117 returns true if version is lower than Go 1.17 or empty.
+// version must be in the format 'go1.17', '1.17'.
+// In case of an invalid input returns not-nil error.
+func goVersionLower117(version string) (bool, error) {
+	version = strings.TrimPrefix(version, "go")
+	if version == "" {
+		return false, nil
+	}
+
+	parts := strings.Split(version, ".")
+	if len(parts) != 2 {
+		return false, errors.New(`go version must has format "go<MAJOR>.<MINOR>" or "<MAJOR>.<MINOR>"`)
+	}
+
+	major, err := strconv.Atoi(parts[0])
+	if err != nil {
+		return false, fmt.Errorf("go version major part must be a number: %w", err)
+	}
+	if major < 1 {
+		return true, nil
+	}
+
+	minor, err := strconv.Atoi(parts[1])
+	if err != nil {
+		return false, fmt.Errorf("go version minor part must be a number: %w", err)
+	}
+
+	return minor < 17, nil
+}

tenv_test.go

@@ -14,3 +14,37 @@ func TestAnalyzer(t *testing.T) {
 	testdata := testutil.WithModules(t, analysistest.TestData(), nil)
 	analysistest.Run(t, testdata, tenv.Analyzer, "a")
 }
+
+func TestAnalyzerGo116(t *testing.T) {
+	testdata := testutil.WithModules(t, analysistest.TestData(), nil)
+	a := tenv.Analyzer
+	a.Flags.Parse([]string{"-go", "1.16"})
+	analysistest.Run(t, testdata, a, "go116")
+}
+
+func TestRun(t *testing.T) {
+	t.Run("empty Go version", func(t *testing.T) {
+		for _, goVersion := range []string{
+			"", "go",
+		} {
+			testdata := testutil.WithModules(t, analysistest.TestData(), nil)
+			a := tenv.Analyzer
+			a.Flags.Parse([]string{"-go", goVersion})
+			analysistest.Run(t, testdata, a, "a")
+		}
+	})
+
+	t.Run("invalid Go version", func(t *testing.T) {
+		for _, goVersion := range []string{
+			"go1", "goa.2", "go1.a",
+		} {
+			a := tenv.Analyzer
+			a.Flags.Parse([]string{"-go", goVersion})
+			_, err := a.Run(nil)
+
+			if err == nil {
+				t.Error("expected error, but got <nil>")
+			}
+		}
+	})
+}

testdata/src/go116/go.mod

@@ -0,0 +1,3 @@
+module go116
+
+go 1.16

testdata/src/go116/go116_test.go

@@ -0,0 +1,12 @@
+package go116
+
+import (
+	"os"
+	"testing"
+)
+
+func TestF(t *testing.T) {
+	os.Setenv("a", "b")        // if -go = 1.16, ""
+	err := os.Setenv("a", "b") // if -go = 1.16, ""
+	_ = err
+}