cmd/jsonimports: add static analyzer for consistent "json" imports (#17669)

This migrates an internal tool to open source so that we can run it on the tailscale.com module as well. We add the "util/safediff" also as a dependency of the tool. This PR does not yet set up a CI to run this analyzer. Updates tailscale/corp#791 Signed-off-by: Joe Tsai <joetsai@digital-static.net>
2025-10-28 14:48:02 -07:00
parent 09a2a1048d
commit fcb614a53e
5 changed files with 937 additions and 0 deletions
@@ -0,0 +1,162 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+package main
+
+import (
+	"go/format"
+	"testing"
+
+	"tailscale.com/util/must"
+	"tailscale.com/util/safediff"
+)
+
+func TestFormatFile(t *testing.T) {
+	tests := []struct{ in, want string }{{
+		in: `package foobar
+
+			import (
+				"encoding/json"
+				jsonv2exp "github.com/go-json-experiment/json"
+			)
+
+			func main() {
+				json.Marshal()
+				jsonv2exp.Marshal()
+				{
+					var json T     // deliberately shadow "json" package name
+					json.Marshal() // should not be re-written
+				}
+			}
+		`,
+		want: `package foobar
+
+			import (
+				jsonv1 "encoding/json"
+				jsonv2 "github.com/go-json-experiment/json"
+			)
+
+			func main() {
+				jsonv1.Marshal()
+				jsonv2.Marshal()
+				{
+					var json T     // deliberately shadow "json" package name
+					json.Marshal() // should not be re-written
+				}
+			}
+		`,
+	}, {
+		in: `package foobar
+
+			import (
+				"github.com/go-json-experiment/json"
+				jsonv2exp "github.com/go-json-experiment/json"
+			)
+
+			func main() {
+				json.Marshal()
+				jsonv2exp.Marshal()
+			}
+		`,
+		want: `package foobar
+			import (
+				jsonv2 "github.com/go-json-experiment/json"
+			)
+			func main() {
+				jsonv2.Marshal()
+				jsonv2.Marshal()
+			}
+		`,
+	}, {
+		in: `package foobar
+			import "github.com/go-json-experiment/json/v1"
+			func main() {
+				json.Marshal()
+			}
+		`,
+		want: `package foobar
+			import jsonv1 "github.com/go-json-experiment/json/v1"
+			func main() {
+				jsonv1.Marshal()
+			}
+		`,
+	}, {
+		in: `package foobar
+			import (
+				"encoding/json"
+				jsonv1in2 "github.com/go-json-experiment/json/v1"
+			)
+			func main() {
+				json.Marshal()
+				jsonv1in2.Marshal()
+			}
+		`,
+		want: `package foobar
+			import (
+				jsonv1std "encoding/json"
+				jsonv1 "github.com/go-json-experiment/json/v1"
+			)
+			func main() {
+				jsonv1std.Marshal()
+				jsonv1.Marshal()
+			}
+		`,
+	}, {
+		in: `package foobar
+			import (
+				"encoding/json"
+				jsonv1in2 "github.com/go-json-experiment/json/v1"
+			)
+			func main() {
+				json.Marshal()
+				jsonv1in2.Marshal()
+			}
+		`,
+		want: `package foobar
+			import (
+				jsonv1std "encoding/json"
+				jsonv1 "github.com/go-json-experiment/json/v1"
+			)
+			func main() {
+				jsonv1std.Marshal()
+				jsonv1.Marshal()
+			}
+		`,
+	}, {
+		in: `package foobar
+			import (
+				"encoding/json"
+				j2 "encoding/json/v2"
+				"encoding/json/jsontext"
+			)
+			func main() {
+				json.Marshal()
+				j2.Marshal()
+				jsontext.NewEncoder
+			}
+		`,
+		want: `package foobar
+			import (
+				jsonv1 "encoding/json"
+				jsonv2 "github.com/go-json-experiment/json"
+				"github.com/go-json-experiment/json/jsontext"
+			)
+			func main() {
+				jsonv1.Marshal()
+				jsonv2.Marshal()
+				jsontext.NewEncoder
+			}
+		`,
+	}}
+	for _, tt := range tests {
+		got := string(must.Get(format.Source([]byte(tt.in))))
+		got = string(mustFormatFile([]byte(got)))
+		want := string(must.Get(format.Source([]byte(tt.want))))
+		if got != want {
+			diff, _ := safediff.Lines(got, want, -1)
+			t.Errorf("mismatch (-got +want)\n%s", diff)
+			t.Error(got)
+			t.Error(want)
+		}
+	}
+}