gopls/internal/regtest/expectation.go - tools - Git at Google

 // Copyright 2020 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 package regtest

 import (
 	"fmt"
 	"regexp"
 	"strings"

 	"golang.org/x/tools/internal/lsp"
 	"golang.org/x/tools/internal/lsp/fake"
 	"golang.org/x/tools/internal/lsp/protocol"
 )

 // An Expectation asserts that the state of the editor at a point in time
 // matches an expected condition. This is used for signaling in tests when
 // certain conditions in the editor are met.
 type Expectation interface {
 	// Check determines whether the state of the editor satisfies the
 	// expectation, returning the results that met the condition.
 	Check(State) Verdict
 	// Description is a human-readable description of the expectation.
 	Description() string
 }

 var (
 	// InitialWorkspaceLoad is an expectation that the workspace initial load has
 	// completed. It is verified via workdone reporting.
 	InitialWorkspaceLoad = CompletedWork(lsp.DiagnosticWorkTitle(lsp.FromInitialWorkspaceLoad), 1)
 )

 // A Verdict is the result of checking an expectation against the current
 // editor state.
 type Verdict int

 // Order matters for the following constants: verdicts are sorted in order of
 // decisiveness.
 const (
 	// Met indicates that an expectation is satisfied by the current state.
 	Met Verdict = iota
 	// Unmet indicates that an expectation is not currently met, but could be met
 	// in the future.
 	Unmet
 	// Unmeetable indicates that an expectation cannot be satisfied in the
 	// future.
 	Unmeetable
 )

 func (v Verdict) String() string {
 	switch v {
 	case Met:
 		return "Met"
 	case Unmet:
 		return "Unmet"
 	case Unmeetable:
 		return "Unmeetable"
 	}
 	return fmt.Sprintf("unrecognized verdict %d", v)
 }

 // SimpleExpectation holds an arbitrary check func, and implements the Expectation interface.
 type SimpleExpectation struct {
 	check       func(State) Verdict
 	description string
 }

 // Check invokes e.check.
 func (e SimpleExpectation) Check(s State) Verdict {
 	return e.check(s)
 }

 // Description returns e.descriptin.
 func (e SimpleExpectation) Description() string {
 	return e.description
 }

 // OnceMet returns an Expectation that, once the precondition is met, asserts
 // that mustMeet is met.
 func OnceMet(precondition Expectation, mustMeet Expectation) *SimpleExpectation {
 	check := func(s State) Verdict {
 		switch pre := precondition.Check(s); pre {
 		case Unmeetable:
 			return Unmeetable
 		case Met:
 			verdict := mustMeet.Check(s)
 			if verdict != Met {
 				return Unmeetable
 			}
 			return Met
 		default:
 			return Unmet
 		}
 	}
 	return &SimpleExpectation{
 		check:       check,
 		description: fmt.Sprintf("once %q is met, must have %q", precondition.Description(), mustMeet.Description()),
 	}
 }

 // ReadDiagnostics is an 'expectation' that is used to read diagnostics
 // atomically. It is intended to be used with 'OnceMet'.
 func ReadDiagnostics(fileName string, into *protocol.PublishDiagnosticsParams) *SimpleExpectation {
 	check := func(s State) Verdict {
 		diags, ok := s.diagnostics[fileName]
 		if !ok {
 			return Unmeetable
 		}
 		*into = *diags
 		return Met
 	}
 	return &SimpleExpectation{
 		check:       check,
 		description: fmt.Sprintf("read diagnostics for %q", fileName),
 	}
 }

 // NoOutstandingWork asserts that there is no work initiated using the LSP
 // $/progress API that has not completed.
 func NoOutstandingWork() SimpleExpectation {
 	check := func(s State) Verdict {
 		if len(s.outstandingWork) == 0 {
 			return Met
 		}
 		return Unmet
 	}
 	return SimpleExpectation{
 		check:       check,
 		description: "no outstanding work",
 	}
 }

 // NoShowMessage asserts that the editor has not received a ShowMessage.
 func NoShowMessage() SimpleExpectation {
 	check := func(s State) Verdict {
 		if len(s.showMessage) == 0 {
 			return Met
 		}
 		return Unmeetable
 	}
 	return SimpleExpectation{
 		check:       check,
 		description: "no ShowMessage received",
 	}
 }

 // ShownMessage asserts that the editor has received a ShownMessage with the
 // given title.
 func ShownMessage(title string) SimpleExpectation {
 	check := func(s State) Verdict {
 		for _, m := range s.showMessage {
 			if strings.Contains(m.Message, title) {
 				return Met
 			}
 		}
 		return Unmet
 	}
 	return SimpleExpectation{
 		check:       check,
 		description: "received ShowMessage",
 	}
 }

 // ShowMessageRequest asserts that the editor has received a ShowMessageRequest
 // with an action item that has the given title.
 func ShowMessageRequest(title string) SimpleExpectation {
 	check := func(s State) Verdict {
 		if len(s.showMessageRequest) == 0 {
 			return Unmet
 		}
 		// Only check the most recent one.
 		m := s.showMessageRequest[len(s.showMessageRequest)-1]
 		if len(m.Actions) == 0 || len(m.Actions) > 1 {
 			return Unmet
 		}
 		if m.Actions[0].Title == title {
 			return Met
 		}
 		return Unmet
 	}
 	return SimpleExpectation{
 		check:       check,
 		description: "received ShowMessageRequest",
 	}
 }

 // CompletedWork expects a work item to have been completed >= atLeast times.
 //
 // Since the Progress API doesn't include any hidden metadata, we must use the
 // progress notification title to identify the work we expect to be completed.
 func CompletedWork(title string, atLeast int) SimpleExpectation {
 	check := func(s State) Verdict {
 		if s.completedWork[title] >= atLeast {
 			return Met
 		}
 		return Unmet
 	}
 	return SimpleExpectation{
 		check:       check,
 		description: fmt.Sprintf("completed work %q at least %d time(s)", title, atLeast),
 	}
 }

 // OutstandingWork expects a work item to be outstanding. The given title must
 // be an exact match, whereas the given msg must only be contained in the work
 // item's message.
 func OutstandingWork(title, msg string) SimpleExpectation {
 	check := func(s State) Verdict {
 		for _, work := range s.outstandingWork {
 			if work.title == title && strings.Contains(work.msg, msg) {
 				return Met
 			}
 		}
 		return Unmet
 	}
 	return SimpleExpectation{
 		check:       check,
 		description: fmt.Sprintf("outstanding work: %s", title),
 	}
 }

 // LogExpectation is an expectation on the log messages received by the editor
 // from gopls.
 type LogExpectation struct {
 	check       func([]*protocol.LogMessageParams) Verdict
 	description string
 }

 // Check implements the Expectation interface.
 func (e LogExpectation) Check(s State) Verdict {
 	return e.check(s.logs)
 }

 // Description implements the Expectation interface.
 func (e LogExpectation) Description() string {
 	return e.description
 }

 // NoErrorLogs asserts that the client has not received any log messages of
 // error severity.
 func NoErrorLogs() LogExpectation {
 	return NoLogMatching(protocol.Error, "")
 }

 // LogMatching asserts that the client has received a log message
 // of type typ matching the regexp re.
 func LogMatching(typ protocol.MessageType, re string, count int) LogExpectation {
 	rec, err := regexp.Compile(re)
 	if err != nil {
 		panic(err)
 	}
 	check := func(msgs []*protocol.LogMessageParams) Verdict {
 		var found int
 		for _, msg := range msgs {
 			if msg.Type == typ && rec.Match([]byte(msg.Message)) {
 				found++
 			}
 		}
 		if found == count {
 			return Met
 		}
 		return Unmet
 	}
 	return LogExpectation{
 		check:       check,
 		description: fmt.Sprintf("log message matching %q", re),
 	}
 }

 // NoLogMatching asserts that the client has not received a log message
 // of type typ matching the regexp re. If re is an empty string, any log
 // message is considered a match.
 func NoLogMatching(typ protocol.MessageType, re string) LogExpectation {
 	var r *regexp.Regexp
 	if re != "" {
 		var err error
 		r, err = regexp.Compile(re)
 		if err != nil {
 			panic(err)
 		}
 	}
 	check := func(msgs []*protocol.LogMessageParams) Verdict {
 		for _, msg := range msgs {
 			if msg.Type != typ {
 				continue
 			}
 			if r == nil || r.Match([]byte(msg.Message)) {
 				return Unmeetable
 			}
 		}
 		return Met
 	}
 	return LogExpectation{
 		check:       check,
 		description: fmt.Sprintf("no log message matching %q", re),
 	}
 }

 // RegistrationExpectation is an expectation on the capability registrations
 // received by the editor from gopls.
 type RegistrationExpectation struct {
 	check       func([]*protocol.RegistrationParams) Verdict
 	description string
 }

 // Check implements the Expectation interface.
 func (e RegistrationExpectation) Check(s State) Verdict {
 	return e.check(s.registrations)
 }

 // Description implements the Expectation interface.
 func (e RegistrationExpectation) Description() string {
 	return e.description
 }

 // RegistrationMatching asserts that the client has received a capability
 // registration matching the given regexp.
 func RegistrationMatching(re string) RegistrationExpectation {
 	rec, err := regexp.Compile(re)
 	if err != nil {
 		panic(err)
 	}
 	check := func(params []*protocol.RegistrationParams) Verdict {
 		for _, p := range params {
 			for _, r := range p.Registrations {
 				if rec.Match([]byte(r.Method)) {
 					return Met
 				}
 			}
 		}
 		return Unmet
 	}
 	return RegistrationExpectation{
 		check:       check,
 		description: fmt.Sprintf("registration matching %q", re),
 	}
 }

 // UnregistrationExpectation is an expectation on the capability
 // unregistrations received by the editor from gopls.
 type UnregistrationExpectation struct {
 	check       func([]*protocol.UnregistrationParams) Verdict
 	description string
 }

 // Check implements the Expectation interface.
 func (e UnregistrationExpectation) Check(s State) Verdict {
 	return e.check(s.unregistrations)
 }

 // Description implements the Expectation interface.
 func (e UnregistrationExpectation) Description() string {
 	return e.description
 }

 // UnregistrationMatching asserts that the client has received an
 // unregistration whose ID matches the given regexp.
 func UnregistrationMatching(re string) UnregistrationExpectation {
 	rec, err := regexp.Compile(re)
 	if err != nil {
 		panic(err)
 	}
 	check := func(params []*protocol.UnregistrationParams) Verdict {
 		for _, p := range params {
 			for _, r := range p.Unregisterations {
 				if rec.Match([]byte(r.Method)) {
 					return Met
 				}
 			}
 		}
 		return Unmet
 	}
 	return UnregistrationExpectation{
 		check:       check,
 		description: fmt.Sprintf("unregistration matching %q", re),
 	}
 }

 // A DiagnosticExpectation is a condition that must be met by the current set
 // of diagnostics for a file.
 type DiagnosticExpectation struct {
 	// optionally, the position of the diagnostic and the regex used to calculate it.
 	pos *fake.Pos
 	re  string

 	// optionally, the message that the diagnostic should contain.
 	message string

 	// whether the expectation is that the diagnostic is present, or absent.
 	present bool

 	// path is the scratch workdir-relative path to the file being asserted on.
 	path string
 }

 // Check implements the Expectation interface.
 func (e DiagnosticExpectation) Check(s State) Verdict {
 	diags, ok := s.diagnostics[e.path]
 	if !ok {
 		if !e.present {
 			return Met
 		}
 		return Unmet
 	}

 	found := false
 	for _, d := range diags.Diagnostics {
 		if e.pos != nil {
 			if d.Range.Start.Line != float64(e.pos.Line) || d.Range.Start.Character != float64(e.pos.Column) {
 				continue
 			}
 		}
 		if e.message != "" {
 			if !strings.Contains(d.Message, e.message) {
 				continue
 			}
 		}
 		found = true
 		break
 	}

 	if found == e.present {
 		return Met
 	}
 	return Unmet
 }

 // Description implements the Expectation interface.
 func (e DiagnosticExpectation) Description() string {
 	desc := e.path + ":"
 	if !e.present {
 		desc += " no"
 	}
 	desc += " diagnostic"
 	if e.pos != nil {
 		desc += fmt.Sprintf(" at {line:%d, column:%d}", e.pos.Line, e.pos.Column)
 		if e.re != "" {
 			desc += fmt.Sprintf(" (location of %q)", e.re)
 		}
 	}
 	if e.message != "" {
 		desc += fmt.Sprintf(" with message %q", e.message)
 	}
 	return desc
 }

 // EmptyDiagnostics asserts that empty diagnostics are sent for the
 // workspace-relative path name.
 func EmptyDiagnostics(name string) Expectation {
 	check := func(s State) Verdict {
 		if diags := s.diagnostics[name]; diags != nil && len(diags.Diagnostics) == 0 {
 			return Met
 		}
 		return Unmet
 	}
 	return SimpleExpectation{
 		check:       check,
 		description: "empty diagnostics",
 	}
 }

 // NoDiagnostics asserts that no diagnostics are sent for the
 // workspace-relative path name. It should be used primarily in conjunction
 // with a OnceMet, as it has to check that all outstanding diagnostics have
 // already been delivered.
 func NoDiagnostics(name string) Expectation {
 	check := func(s State) Verdict {
 		if _, ok := s.diagnostics[name]; !ok {
 			return Met
 		}
 		return Unmet
 	}
 	return SimpleExpectation{
 		check:       check,
 		description: "no diagnostics",
 	}
 }

 // AnyDiagnosticAtCurrentVersion asserts that there is a diagnostic report for
 // the current edited version of the buffer corresponding to the given
 // workdir-relative pathname.
 func (e *Env) AnyDiagnosticAtCurrentVersion(name string) Expectation {
 	version := e.Editor.BufferVersion(name)
 	check := func(s State) Verdict {
 		diags, ok := s.diagnostics[name]
 		if ok && diags.Version == float64(version) {
 			return Met
 		}
 		return Unmet
 	}
 	return SimpleExpectation{
 		check:       check,
 		description: fmt.Sprintf("any diagnostics at version %d", version),
 	}
 }

 // DiagnosticAtRegexp expects that there is a diagnostic entry at the start
 // position matching the regexp search string re in the buffer specified by
 // name. Note that this currently ignores the end position.
 func (e *Env) DiagnosticAtRegexp(name, re string) DiagnosticExpectation {
 	e.T.Helper()
 	pos := e.RegexpSearch(name, re)
 	return DiagnosticExpectation{path: name, pos: &pos, re: re, present: true}
 }

 // DiagnosticAt asserts that there is a diagnostic entry at the position
 // specified by line and col, for the workdir-relative path name.
 func DiagnosticAt(name string, line, col int) DiagnosticExpectation {
 	return DiagnosticExpectation{path: name, pos: &fake.Pos{Line: line, Column: col}, present: true}
 }

 // NoDiagnosticAtRegexp expects that there is no diagnostic entry at the start
 // position matching the regexp search string re in the buffer specified by
 // name. Note that this currently ignores the end position.
 // This should only be used in combination with OnceMet for a given condition,
 // otherwise it may always succeed.
 func (e *Env) NoDiagnosticAtRegexp(name, re string) DiagnosticExpectation {
 	e.T.Helper()
 	pos := e.RegexpSearch(name, re)
 	return DiagnosticExpectation{path: name, pos: &pos, re: re, present: false}
 }

 // NoDiagnosticAt asserts that there is no diagnostic entry at the position
 // specified by line and col, for the workdir-relative path name.
 // This should only be used in combination with OnceMet for a given condition,
 // otherwise it may always succeed.
 func NoDiagnosticAt(name string, line, col int) DiagnosticExpectation {
 	return DiagnosticExpectation{path: name, pos: &fake.Pos{Line: line, Column: col}, present: false}
 }

 // NoDiagnosticWithMessage asserts that there is no diagnostic entry with the
 // given message.
 //
 // This should only be used in combination with OnceMet for a given condition,
 // otherwise it may always succeed.
 func NoDiagnosticWithMessage(name, msg string) DiagnosticExpectation {
 	return DiagnosticExpectation{path: name, message: msg, present: false}
 }
	// Copyright 2020 The Go Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	package regtest

	import (
	"fmt"
	"regexp"
	"strings"

	"golang.org/x/tools/internal/lsp"
	"golang.org/x/tools/internal/lsp/fake"
	"golang.org/x/tools/internal/lsp/protocol"
	)

	// An Expectation asserts that the state of the editor at a point in time
	// matches an expected condition. This is used for signaling in tests when
	// certain conditions in the editor are met.
	type Expectation interface {
	// Check determines whether the state of the editor satisfies the
	// expectation, returning the results that met the condition.
	Check(State) Verdict
	// Description is a human-readable description of the expectation.
	Description() string
	}

	var (
	// InitialWorkspaceLoad is an expectation that the workspace initial load has
	// completed. It is verified via workdone reporting.
	InitialWorkspaceLoad = CompletedWork(lsp.DiagnosticWorkTitle(lsp.FromInitialWorkspaceLoad), 1)
	)

	// A Verdict is the result of checking an expectation against the current
	// editor state.
	type Verdict int

	// Order matters for the following constants: verdicts are sorted in order of
	// decisiveness.
	const (
	// Met indicates that an expectation is satisfied by the current state.
	Met Verdict = iota
	// Unmet indicates that an expectation is not currently met, but could be met
	// in the future.
	Unmet
	// Unmeetable indicates that an expectation cannot be satisfied in the
	// future.
	Unmeetable
	)

	func (v Verdict) String() string {
	switch v {
	case Met:
	return "Met"
	case Unmet:
	return "Unmet"
	case Unmeetable:
	return "Unmeetable"
	}
	return fmt.Sprintf("unrecognized verdict %d", v)
	}

	// SimpleExpectation holds an arbitrary check func, and implements the Expectation interface.
	type SimpleExpectation struct {
	check func(State) Verdict
	description string
	}

	// Check invokes e.check.
	func (e SimpleExpectation) Check(s State) Verdict {
	return e.check(s)
	}

	// Description returns e.descriptin.
	func (e SimpleExpectation) Description() string {
	return e.description
	}

	// OnceMet returns an Expectation that, once the precondition is met, asserts
	// that mustMeet is met.
	func OnceMet(precondition Expectation, mustMeet Expectation) *SimpleExpectation {
	check := func(s State) Verdict {
	switch pre := precondition.Check(s); pre {
	case Unmeetable:
	return Unmeetable
	case Met:
	verdict := mustMeet.Check(s)
	if verdict != Met {
	return Unmeetable
	}
	return Met
	default:
	return Unmet
	}
	}
	return &SimpleExpectation{
	check: check,
	description: fmt.Sprintf("once %q is met, must have %q", precondition.Description(), mustMeet.Description()),
	}
	}

	// ReadDiagnostics is an 'expectation' that is used to read diagnostics
	// atomically. It is intended to be used with 'OnceMet'.
	func ReadDiagnostics(fileName string, into protocol.PublishDiagnosticsParams) SimpleExpectation {
	check := func(s State) Verdict {
	diags, ok := s.diagnostics[fileName]
	if !ok {
	return Unmeetable
	}
	into = diags
	return Met
	}
	return &SimpleExpectation{
	check: check,
	description: fmt.Sprintf("read diagnostics for %q", fileName),
	}
	}

	// NoOutstandingWork asserts that there is no work initiated using the LSP
	// $/progress API that has not completed.
	func NoOutstandingWork() SimpleExpectation {
	check := func(s State) Verdict {
	if len(s.outstandingWork) == 0 {
	return Met
	}
	return Unmet
	}
	return SimpleExpectation{
	check: check,
	description: "no outstanding work",
	}
	}

	// NoShowMessage asserts that the editor has not received a ShowMessage.
	func NoShowMessage() SimpleExpectation {
	check := func(s State) Verdict {
	if len(s.showMessage) == 0 {
	return Met
	}
	return Unmeetable
	}
	return SimpleExpectation{
	check: check,
	description: "no ShowMessage received",
	}
	}

	// ShownMessage asserts that the editor has received a ShownMessage with the
	// given title.
	func ShownMessage(title string) SimpleExpectation {
	check := func(s State) Verdict {
	for _, m := range s.showMessage {
	if strings.Contains(m.Message, title) {
	return Met
	}
	}
	return Unmet
	}
	return SimpleExpectation{
	check: check,
	description: "received ShowMessage",
	}
	}

	// ShowMessageRequest asserts that the editor has received a ShowMessageRequest
	// with an action item that has the given title.
	func ShowMessageRequest(title string) SimpleExpectation {
	check := func(s State) Verdict {
	if len(s.showMessageRequest) == 0 {
	return Unmet
	}
	// Only check the most recent one.
	m := s.showMessageRequest[len(s.showMessageRequest)-1]
	if len(m.Actions) == 0 \|\| len(m.Actions) > 1 {
	return Unmet
	}
	if m.Actions[0].Title == title {
	return Met
	}
	return Unmet
	}
	return SimpleExpectation{
	check: check,
	description: "received ShowMessageRequest",
	}
	}

	// CompletedWork expects a work item to have been completed >= atLeast times.
	//
	// Since the Progress API doesn't include any hidden metadata, we must use the
	// progress notification title to identify the work we expect to be completed.
	func CompletedWork(title string, atLeast int) SimpleExpectation {
	check := func(s State) Verdict {
	if s.completedWork[title] >= atLeast {
	return Met
	}
	return Unmet
	}
	return SimpleExpectation{
	check: check,
	description: fmt.Sprintf("completed work %q at least %d time(s)", title, atLeast),
	}
	}

	// OutstandingWork expects a work item to be outstanding. The given title must
	// be an exact match, whereas the given msg must only be contained in the work
	// item's message.
	func OutstandingWork(title, msg string) SimpleExpectation {
	check := func(s State) Verdict {
	for _, work := range s.outstandingWork {
	if work.title == title && strings.Contains(work.msg, msg) {
	return Met
	}
	}
	return Unmet
	}
	return SimpleExpectation{
	check: check,
	description: fmt.Sprintf("outstanding work: %s", title),
	}
	}

	// LogExpectation is an expectation on the log messages received by the editor
	// from gopls.
	type LogExpectation struct {
	check func([]*protocol.LogMessageParams) Verdict
	description string
	}

	// Check implements the Expectation interface.
	func (e LogExpectation) Check(s State) Verdict {
	return e.check(s.logs)
	}

	// Description implements the Expectation interface.
	func (e LogExpectation) Description() string {
	return e.description
	}

	// NoErrorLogs asserts that the client has not received any log messages of
	// error severity.
	func NoErrorLogs() LogExpectation {
	return NoLogMatching(protocol.Error, "")
	}

	// LogMatching asserts that the client has received a log message
	// of type typ matching the regexp re.
	func LogMatching(typ protocol.MessageType, re string, count int) LogExpectation {
	rec, err := regexp.Compile(re)
	if err != nil {
	panic(err)
	}
	check := func(msgs []*protocol.LogMessageParams) Verdict {
	var found int
	for _, msg := range msgs {
	if msg.Type == typ && rec.Match([]byte(msg.Message)) {
	found++
	}
	}
	if found == count {
	return Met
	}
	return Unmet
	}
	return LogExpectation{
	check: check,
	description: fmt.Sprintf("log message matching %q", re),
	}
	}

	// NoLogMatching asserts that the client has not received a log message
	// of type typ matching the regexp re. If re is an empty string, any log
	// message is considered a match.
	func NoLogMatching(typ protocol.MessageType, re string) LogExpectation {
	var r *regexp.Regexp
	if re != "" {
	var err error
	r, err = regexp.Compile(re)
	if err != nil {
	panic(err)
	}
	}
	check := func(msgs []*protocol.LogMessageParams) Verdict {
	for _, msg := range msgs {
	if msg.Type != typ {
	continue
	}
	if r == nil \|\| r.Match([]byte(msg.Message)) {
	return Unmeetable
	}
	}
	return Met
	}
	return LogExpectation{
	check: check,
	description: fmt.Sprintf("no log message matching %q", re),
	}
	}

	// RegistrationExpectation is an expectation on the capability registrations
	// received by the editor from gopls.
	type RegistrationExpectation struct {
	check func([]*protocol.RegistrationParams) Verdict
	description string
	}

	// Check implements the Expectation interface.
	func (e RegistrationExpectation) Check(s State) Verdict {
	return e.check(s.registrations)
	}

	// Description implements the Expectation interface.
	func (e RegistrationExpectation) Description() string {
	return e.description
	}

	// RegistrationMatching asserts that the client has received a capability
	// registration matching the given regexp.
	func RegistrationMatching(re string) RegistrationExpectation {
	rec, err := regexp.Compile(re)
	if err != nil {
	panic(err)
	}
	check := func(params []*protocol.RegistrationParams) Verdict {
	for _, p := range params {
	for _, r := range p.Registrations {
	if rec.Match([]byte(r.Method)) {
	return Met
	}
	}
	}
	return Unmet
	}
	return RegistrationExpectation{
	check: check,
	description: fmt.Sprintf("registration matching %q", re),
	}
	}

	// UnregistrationExpectation is an expectation on the capability
	// unregistrations received by the editor from gopls.
	type UnregistrationExpectation struct {
	check func([]*protocol.UnregistrationParams) Verdict
	description string
	}

	// Check implements the Expectation interface.
	func (e UnregistrationExpectation) Check(s State) Verdict {
	return e.check(s.unregistrations)
	}

	// Description implements the Expectation interface.
	func (e UnregistrationExpectation) Description() string {
	return e.description
	}

	// UnregistrationMatching asserts that the client has received an
	// unregistration whose ID matches the given regexp.
	func UnregistrationMatching(re string) UnregistrationExpectation {
	rec, err := regexp.Compile(re)
	if err != nil {
	panic(err)
	}
	check := func(params []*protocol.UnregistrationParams) Verdict {
	for _, p := range params {
	for _, r := range p.Unregisterations {
	if rec.Match([]byte(r.Method)) {
	return Met
	}
	}
	}
	return Unmet
	}
	return UnregistrationExpectation{
	check: check,
	description: fmt.Sprintf("unregistration matching %q", re),
	}
	}

	// A DiagnosticExpectation is a condition that must be met by the current set
	// of diagnostics for a file.
	type DiagnosticExpectation struct {
	// optionally, the position of the diagnostic and the regex used to calculate it.
	pos *fake.Pos
	re string

	// optionally, the message that the diagnostic should contain.
	message string

	// whether the expectation is that the diagnostic is present, or absent.
	present bool

	// path is the scratch workdir-relative path to the file being asserted on.
	path string
	}

	// Check implements the Expectation interface.
	func (e DiagnosticExpectation) Check(s State) Verdict {
	diags, ok := s.diagnostics[e.path]
	if !ok {
	if !e.present {
	return Met
	}
	return Unmet
	}

	found := false
	for _, d := range diags.Diagnostics {
	if e.pos != nil {
	if d.Range.Start.Line != float64(e.pos.Line) \|\| d.Range.Start.Character != float64(e.pos.Column) {
	continue
	}
	}
	if e.message != "" {
	if !strings.Contains(d.Message, e.message) {
	continue
	}
	}
	found = true
	break
	}

	if found == e.present {
	return Met
	}
	return Unmet
	}

	// Description implements the Expectation interface.
	func (e DiagnosticExpectation) Description() string {
	desc := e.path + ":"
	if !e.present {
	desc += " no"
	}
	desc += " diagnostic"
	if e.pos != nil {
	desc += fmt.Sprintf(" at {line:%d, column:%d}", e.pos.Line, e.pos.Column)
	if e.re != "" {
	desc += fmt.Sprintf(" (location of %q)", e.re)
	}
	}
	if e.message != "" {
	desc += fmt.Sprintf(" with message %q", e.message)
	}
	return desc
	}

	// EmptyDiagnostics asserts that empty diagnostics are sent for the
	// workspace-relative path name.
	func EmptyDiagnostics(name string) Expectation {
	check := func(s State) Verdict {
	if diags := s.diagnostics[name]; diags != nil && len(diags.Diagnostics) == 0 {
	return Met
	}
	return Unmet
	}
	return SimpleExpectation{
	check: check,
	description: "empty diagnostics",
	}
	}

	// NoDiagnostics asserts that no diagnostics are sent for the
	// workspace-relative path name. It should be used primarily in conjunction
	// with a OnceMet, as it has to check that all outstanding diagnostics have
	// already been delivered.
	func NoDiagnostics(name string) Expectation {
	check := func(s State) Verdict {
	if _, ok := s.diagnostics[name]; !ok {
	return Met
	}
	return Unmet
	}
	return SimpleExpectation{
	check: check,
	description: "no diagnostics",
	}
	}

	// AnyDiagnosticAtCurrentVersion asserts that there is a diagnostic report for
	// the current edited version of the buffer corresponding to the given
	// workdir-relative pathname.
	func (e *Env) AnyDiagnosticAtCurrentVersion(name string) Expectation {
	version := e.Editor.BufferVersion(name)
	check := func(s State) Verdict {
	diags, ok := s.diagnostics[name]
	if ok && diags.Version == float64(version) {
	return Met
	}
	return Unmet
	}
	return SimpleExpectation{
	check: check,
	description: fmt.Sprintf("any diagnostics at version %d", version),
	}
	}

	// DiagnosticAtRegexp expects that there is a diagnostic entry at the start
	// position matching the regexp search string re in the buffer specified by
	// name. Note that this currently ignores the end position.
	func (e *Env) DiagnosticAtRegexp(name, re string) DiagnosticExpectation {
	e.T.Helper()
	pos := e.RegexpSearch(name, re)
	return DiagnosticExpectation{path: name, pos: &pos, re: re, present: true}
	}

	// DiagnosticAt asserts that there is a diagnostic entry at the position
	// specified by line and col, for the workdir-relative path name.
	func DiagnosticAt(name string, line, col int) DiagnosticExpectation {
	return DiagnosticExpectation{path: name, pos: &fake.Pos{Line: line, Column: col}, present: true}
	}

	// NoDiagnosticAtRegexp expects that there is no diagnostic entry at the start
	// position matching the regexp search string re in the buffer specified by
	// name. Note that this currently ignores the end position.
	// This should only be used in combination with OnceMet for a given condition,
	// otherwise it may always succeed.
	func (e *Env) NoDiagnosticAtRegexp(name, re string) DiagnosticExpectation {
	e.T.Helper()
	pos := e.RegexpSearch(name, re)
	return DiagnosticExpectation{path: name, pos: &pos, re: re, present: false}
	}

	// NoDiagnosticAt asserts that there is no diagnostic entry at the position
	// specified by line and col, for the workdir-relative path name.
	// This should only be used in combination with OnceMet for a given condition,
	// otherwise it may always succeed.
	func NoDiagnosticAt(name string, line, col int) DiagnosticExpectation {
	return DiagnosticExpectation{path: name, pos: &fake.Pos{Line: line, Column: col}, present: false}
	}

	// NoDiagnosticWithMessage asserts that there is no diagnostic entry with the
	// given message.
	//
	// This should only be used in combination with OnceMet for a given condition,
	// otherwise it may always succeed.
	func NoDiagnosticWithMessage(name, msg string) DiagnosticExpectation {
	return DiagnosticExpectation{path: name, message: msg, present: false}
	}