whatcanGOwrong

go/pkg/mod/mvdan.cc/gofumpt@v0.6.0/format/fuzz_test.go

@@ -0,0 +1,64 @@
+// Copyright (c) 2021, Daniel Martí <mvdan@mvdan.cc>
+// See LICENSE for licensing information
+
+package format
+
+import (
+	"errors"
+	"fmt"
+	"go/scanner"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	qt "github.com/frankban/quicktest"
+	"golang.org/x/tools/txtar"
+)
+
+func FuzzFormat(f *testing.F) {
+	// Initialize the corpus with the Go files from our test scripts.
+	paths, err := filepath.Glob(filepath.Join("..", "testdata", "script", "*.txtar"))
+	qt.Assert(f, err, qt.IsNil)
+	qt.Assert(f, paths, qt.Not(qt.HasLen), 0)
+	for _, path := range paths {
+		archive, err := txtar.ParseFile(path)
+		qt.Assert(f, err, qt.IsNil)
+		for _, file := range archive.Files {
+			f.Logf("adding %s from %s", file.Name, path)
+			if strings.HasSuffix(file.Name, ".go") || strings.Contains(file.Name, ".go.") {
+				f.Add(string(file.Data), int8(18), false) // -lang=1.18
+				f.Add(string(file.Data), int8(1), false)  // -lang=1.1
+				f.Add(string(file.Data), int8(18), true)  // -lang=1.18 -extra
+			}
+		}
+	}
+
+	f.Fuzz(func(t *testing.T, src string,
+		majorVersion int8, // Empty version if negative, 1.N otherwise.
+		extraRules bool,
+	) {
+		// TODO: also fuzz Options.ModulePath
+		opts := Options{ExtraRules: extraRules}
+		if majorVersion >= 0 {
+			opts.LangVersion = fmt.Sprintf("1.%d", majorVersion)
+		}
+
+		orig := []byte(src)
+		formatted, err := Source(orig, opts)
+		if errors.As(err, &scanner.ErrorList{}) {
+			return // invalid syntax from parsing
+		}
+		qt.Assert(t, err, qt.IsNil)
+		_ = formatted
+
+		// TODO: verify that the result is idempotent
+
+		// TODO: verify that, if the input was valid Go 1.N syntax,
+		// so is the output (how? go/parser lacks an option)
+
+		// TODO: check calling format.Node directly as well
+
+		qt.Assert(t, string(orig), qt.Equals, src,
+			qt.Commentf("input source bytes were modified"))
+	})
+}