gopls/internal/lsp/cmd: add instrumentation for TestFix

To help pin down golang/go#59475, add some additional debug output.

For golang/go#59475

Change-Id: Ibed0743bcc00a51c0fa56a15fb7fe1be88ec403c
Reviewed-on: https://go-review.googlesource.com/c/tools/+/486799
Reviewed-by: Alan Donovan <adonovan@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
gopls-CI: kokoro <noreply+kokoro@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>

Author: findleyr

gopls/internal/lsp/cmd/suggested_fix.go

@@ -9,6 +9,7 @@ import (
 	"flag"
 	"fmt"
 	"io/ioutil"
+	"log"
 	"os"
 
 	"golang.org/x/tools/gopls/internal/lsp/protocol"
@@ -41,11 +42,16 @@ fix-flags:
 	printFlagDefaults(f)
 }
 
+const DebugSuggestedFixEnvVar = "_DEBUG_SUGGESTED_FIX"
+
 // Run performs diagnostic checks on the file specified and either;
 // - if -w is specified, updates the file in place;
 // - if -d is specified, prints out unified diffs of the changes; or
 // - otherwise, prints the new versions to stdout.
 func (s *suggestedFix) Run(ctx context.Context, args ...string) error {
+	// For debugging golang/go#59475, enable some additional output.
+	var debug = os.Getenv(DebugSuggestedFixEnvVar) == "true"
+
 	if len(args) < 1 {
 		return tool.CommandLineErrorf("fix expects at least 1 argument")
 	}
@@ -84,6 +90,9 @@ func (s *suggestedFix) Run(ctx context.Context, args ...string) error {
 		// LSP requires a slice, not a nil.
 		file.diagnostics = []protocol.Diagnostic{}
 	}
+	if debug {
+		log.Printf("file diagnostics: %#v", file.diagnostics)
+	}
 	p := protocol.CodeActionParams{
 		TextDocument: protocol.TextDocumentIdentifier{
 			URI: protocol.URIFromSpanURI(uri),
@@ -98,6 +107,10 @@ func (s *suggestedFix) Run(ctx context.Context, args ...string) error {
 	if err != nil {
 		return fmt.Errorf("%v: %v", from, err)
 	}
+	if debug {
+		log.Printf("code actions: %#v", actions)
+	}
+
 	var edits []protocol.TextEdit
 	for _, a := range actions {
 		if a.Command != nil {

gopls/internal/lsp/cmd/test/integration_test.go

@@ -712,7 +712,7 @@ func f() (int, string) { return 0, "" }
 		res.checkExit(true)
 		got := res.stdout
 		if got != want {
-			t.Errorf("fix: got <<%s>>, want <<%s>>", got, want)
+			t.Errorf("fix: got <<%s>>, want <<%s>>\nstderr:\n%s", got, want, res.stderr)
 		}
 	}
 	// TODO(adonovan): more tests:
@@ -800,16 +800,19 @@ func gopls(t *testing.T, dir string, args ...string) *result {
 		t.Fatalf("dir is not absolute: %s", dir)
 	}
 
-	cmd := exec.Command(os.Args[0], args...)
-	cmd.Env = append(os.Environ(), "ENTRYPOINT=goplsMain")
-	cmd.Dir = dir
-	cmd.Stdout = new(bytes.Buffer)
-	cmd.Stderr = new(bytes.Buffer)
+	goplsCmd := exec.Command(os.Args[0], args...)
+	goplsCmd.Env = append(os.Environ(),
+		"ENTRYPOINT=goplsMain",
+		fmt.Sprintf("%s=true", cmd.DebugSuggestedFixEnvVar),
+	)
+	goplsCmd.Dir = dir
+	goplsCmd.Stdout = new(bytes.Buffer)
+	goplsCmd.Stderr = new(bytes.Buffer)
 
-	cmdErr := cmd.Run()
+	cmdErr := goplsCmd.Run()
 
-	stdout := strings.ReplaceAll(fmt.Sprint(cmd.Stdout), dir, ".")
-	stderr := strings.ReplaceAll(fmt.Sprint(cmd.Stderr), dir, ".")
+	stdout := strings.ReplaceAll(fmt.Sprint(goplsCmd.Stdout), dir, ".")
+	stderr := strings.ReplaceAll(fmt.Sprint(goplsCmd.Stderr), dir, ".")
 	exitcode := 0
 	if cmdErr != nil {
 		if exitErr, ok := cmdErr.(*exec.ExitError); ok {