// 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 (
	"context"
	"fmt"
	"log"
	"os"
	"testing"
	"time"

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

// Use mod.com for all go.mod files due to golang/go#35230.
const exampleProgram = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

import "fmt"

func main() {
	fmt.Println("Hello World.")
}`

func TestDiagnosticErrorInEditedFile(t *testing.T) {
	// This test is very basic: start with a clean Go program, make an error, and
	// get a diagnostic for that error. However, it also demonstrates how to
	// combine Expectations to await more complex state in the editor.
	runner.Run(t, exampleProgram, func(t *testing.T, env *Env) {
		// Deleting the 'n' at the end of Println should generate a single error
		// diagnostic.
		env.OpenFile("main.go")
		env.RegexpReplace("main.go", "Printl(n)", "")
		env.Await(
			// Once we have gotten diagnostics for the change above, we should
			// satisfy the DiagnosticAtRegexp assertion.
			OnceMet(
				CompletedWork(lsp.DiagnosticWorkTitle(lsp.FromDidChange), 1),
				env.DiagnosticAtRegexp("main.go", "Printl"),
			),
			// Assert that this test has sent no error logs to the client. This is not
			// strictly necessary for testing this regression, but is included here
			// as an example of using the NoErrorLogs() expectation. Feel free to
			// delete.
			NoErrorLogs(),
		)
	})
}

const onlyMod = `
-- go.mod --
module mod.com

go 1.12
`

func TestMissingImportDiagsClearOnFirstFile(t *testing.T) {
	t.Parallel()
	runner.Run(t, onlyMod, func(t *testing.T, env *Env) {
		env.CreateBuffer("main.go", `package main

func m() {
	log.Println()
}
`)
		env.Await(
			env.DiagnosticAtRegexp("main.go", "log"),
		)
		env.SaveBuffer("main.go")
		env.Await(
			EmptyDiagnostics("main.go"),
		)
	})
}

const brokenFile = `package main

const Foo = "abc
`

func TestDiagnosticErrorInNewFile(t *testing.T) {
	runner.Run(t, brokenFile, func(t *testing.T, env *Env) {
		env.CreateBuffer("broken.go", brokenFile)
		env.Await(env.DiagnosticAtRegexp("broken.go", "\"abc"))
	})
}

// badPackage contains a duplicate definition of the 'a' const.
const badPackage = `
-- go.mod --
module mod.com

go 1.12
-- a.go --
package consts

const a = 1
-- b.go --
package consts

const a = 2
`

func TestDiagnosticClearingOnEdit(t *testing.T) {
	runner.Run(t, badPackage, func(t *testing.T, env *Env) {
		env.OpenFile("b.go")
		env.Await(env.DiagnosticAtRegexp("a.go", "a = 1"), env.DiagnosticAtRegexp("b.go", "a = 2"))

		// Fix the error by editing the const name in b.go to `b`.
		env.RegexpReplace("b.go", "(a) = 2", "b")
		env.Await(
			EmptyDiagnostics("a.go"),
			EmptyDiagnostics("b.go"),
		)
	})
}

func TestDiagnosticClearingOnDelete_Issue37049(t *testing.T) {
	runner.Run(t, badPackage, func(t *testing.T, env *Env) {
		env.OpenFile("a.go")
		env.Await(env.DiagnosticAtRegexp("a.go", "a = 1"), env.DiagnosticAtRegexp("b.go", "a = 2"))
		env.RemoveWorkspaceFile("b.go")

		env.Await(EmptyDiagnostics("a.go"), EmptyDiagnostics("b.go"))
	})
}

func TestDiagnosticClearingOnClose(t *testing.T) {
	runner.Run(t, badPackage, func(t *testing.T, env *Env) {
		env.CreateBuffer("c.go", `package consts

const a = 3`)
		env.Await(
			env.DiagnosticAtRegexp("a.go", "a = 1"),
			env.DiagnosticAtRegexp("b.go", "a = 2"),
			env.DiagnosticAtRegexp("c.go", "a = 3"))
		env.CloseBuffer("c.go")
		env.Await(
			env.DiagnosticAtRegexp("a.go", "a = 1"),
			env.DiagnosticAtRegexp("b.go", "a = 2"),
			EmptyDiagnostics("c.go"))
	})
}

// Tests golang/go#37978.
func TestIssue37978(t *testing.T) {
	runner.Run(t, exampleProgram, func(t *testing.T, env *Env) {
		// Create a new workspace-level directory and empty file.
		env.CreateBuffer("c/c.go", "")

		// Write the file contents with a missing import.
		env.EditBuffer("c/c.go", fake.Edit{
			Text: `package c

const a = http.MethodGet
`,
		})
		env.Await(
			env.DiagnosticAtRegexp("c/c.go", "http.MethodGet"),
		)
		// Save file, which will organize imports, adding the expected import.
		// Expect the diagnostics to clear.
		env.SaveBuffer("c/c.go")
		env.Await(
			EmptyDiagnostics("c/c.go"),
		)
	})
}

// Tests golang/go#38878: good a.go, bad a_test.go, remove a_test.go but its errors remain
// If the file is open in the editor, this is working as intended
// If the file is not open in the editor, the errors go away
const test38878 = `
-- go.mod --
module foo

-- a.go --
package x

func f() {}

-- a_test.go --
package x

import "testing"

func TestA(t *testing.T) {
	f(3)
}
`

func TestRmTest38878Close(t *testing.T) {
	runner.Run(t, test38878, func(t *testing.T, env *Env) {
		env.OpenFile("a_test.go")
		env.Await(DiagnosticAt("a_test.go", 5, 3))
		env.CloseBuffer("a_test.go")
		env.RemoveWorkspaceFile("a_test.go")
		// diagnostics go away
		env.Await(EmptyDiagnostics("a_test.go"))
	})
}
func TestRmTest38878(t *testing.T) {
	log.SetFlags(log.Lshortfile)
	runner.Run(t, test38878, func(t *testing.T, env *Env) {
		env.OpenFile("a_test.go")
		env.Await(DiagnosticAt("a_test.go", 5, 3))
		env.Sandbox.Workdir.RemoveFile(context.Background(), "a_test.go")
		// diagnostics remain after giving gopls a chance to do something
		// (there is not yet a better way to decide gopls isn't going
		// to do anything)
		time.Sleep(time.Second)
		env.Await(DiagnosticAt("a_test.go", 5, 3))
	})
}

// TestNoMod confirms that gopls continues to work when a user adds a go.mod
// file to their workspace.
func TestNoMod(t *testing.T) {
	const noMod = `
-- main.go --
package main

import "mod.com/bob"

func main() {
	bob.Hello()
}
-- bob/bob.go --
package bob

func Hello() {
	var x int
}
`

	t.Run("manual", func(t *testing.T) {
		runner.Run(t, noMod, func(t *testing.T, env *Env) {
			env.Await(
				env.DiagnosticAtRegexp("main.go", `"mod.com/bob"`),
			)
			env.CreateBuffer("go.mod", `module mod.com

	go 1.12
`)
			env.SaveBuffer("go.mod")
			env.Await(
				EmptyDiagnostics("main.go"),
				env.DiagnosticAtRegexp("bob/bob.go", "x"),
			)
		})
	})
	t.Run("initialized", func(t *testing.T) {
		runner.Run(t, noMod, func(t *testing.T, env *Env) {
			env.Await(
				env.DiagnosticAtRegexp("main.go", `"mod.com/bob"`),
			)
			if err := env.Sandbox.RunGoCommand(env.Ctx, "mod", "init", "mod.com"); err != nil {
				t.Fatal(err)
			}
			env.Await(
				EmptyDiagnostics("main.go"),
				env.DiagnosticAtRegexp("bob/bob.go", "x"),
			)
		})
	})
}

// Tests golang/go#38267.
func TestIssue38267(t *testing.T) {
	const testPackage = `
-- go.mod --
module mod.com

go 1.12
-- lib.go --
package lib

func Hello(x string) {
	_ = x
}
-- lib_test.go --
package lib

import "testing"

type testStruct struct{
	name string
}

func TestHello(t *testing.T) {
	testStructs := []*testStruct{
		&testStruct{"hello"},
		&testStruct{"goodbye"},
	}
	for y := range testStructs {
		_ = y
	}
}
`

	runner.Run(t, testPackage, func(t *testing.T, env *Env) {
		env.OpenFile("lib_test.go")
		env.Await(
			DiagnosticAt("lib_test.go", 10, 2),
			DiagnosticAt("lib_test.go", 11, 2),
		)
		env.OpenFile("lib.go")
		env.RegexpReplace("lib.go", "_ = x", "var y int")
		env.Await(
			env.DiagnosticAtRegexp("lib.go", "y int"),
			EmptyDiagnostics("lib_test.go"),
		)
	})
}

// Tests golang/go#38328.
func TestPackageChange_Issue38328(t *testing.T) {
	const packageChange = `
-- go.mod --
module fake
-- a.go --
package foo
func main() {}
`
	runner.Run(t, packageChange, func(t *testing.T, env *Env) {
		env.OpenFile("a.go")
		env.RegexpReplace("a.go", "foo", "foox")
		env.Await(
			// When the bug reported in #38328 was present, we didn't get erroneous
			// file diagnostics until after the didChange message generated by the
			// package renaming was fully processed. Therefore, in order for this
			// test to actually exercise the bug, we must wait until that work has
			// completed.
			OnceMet(
				CompletedWork(lsp.DiagnosticWorkTitle(lsp.FromDidChange), 1),
				NoDiagnostics("a.go"),
			),
		)
	})
}

const testPackageWithRequire = `
-- go.mod --
module mod.com

go 1.12

require (
	foo.test v1.2.3
)
-- print.go --
package lib

import (
	"fmt"

	"foo.test/bar"
)

func PrintAnswer() {
	fmt.Printf("answer: %s", bar.Answer)
}
`

const testPackageWithRequireProxy = `
-- foo.test@v1.2.3/go.mod --
module foo.test

go 1.12
-- foo.test@v1.2.3/bar/const.go --
package bar

const Answer = 42
`

func TestResolveDiagnosticWithDownload(t *testing.T) {
	runner.Run(t, testPackageWithRequire, func(t *testing.T, env *Env) {
		env.OpenFile("print.go")
		// Check that gopackages correctly loaded this dependency. We should get a
		// diagnostic for the wrong formatting type.
		// TODO: we should be able to easily also match the diagnostic message.
		env.Await(env.DiagnosticAtRegexp("print.go", "fmt.Printf"))
	}, WithProxy(testPackageWithRequireProxy))
}

func TestMissingDependency(t *testing.T) {
	runner.Run(t, testPackageWithRequire, func(t *testing.T, env *Env) {
		env.OpenFile("print.go")
		env.Await(LogMatching(protocol.Error, "initial workspace load failed"))
	})
}

// Tests golang/go#36951.
func TestAdHocPackages_Issue36951(t *testing.T) {
	const adHoc = `
-- b/b.go --
package b

func Hello() {
	var x int
}
`
	runner.Run(t, adHoc, func(t *testing.T, env *Env) {
		env.OpenFile("b/b.go")
		env.Await(env.DiagnosticAtRegexp("b/b.go", "x"))
	})
}

// Tests golang/go#37984: GOPATH should be read from the go command.
func TestNoGOPATH_Issue37984(t *testing.T) {
	const missingImport = `
-- main.go --
package main

func _() {
	fmt.Println("Hello World")
}
`
	runner.Run(t, missingImport, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		env.Await(env.DiagnosticAtRegexp("main.go", "fmt"))
		env.SaveBuffer("main.go")
		env.Await(EmptyDiagnostics("main.go"))
	}, WithEditorConfig(fake.EditorConfig{Env: []string{"GOPATH="}}))
}

// Tests golang/go#38669.
func TestEqualInEnv_Issue38669(t *testing.T) {
	const missingImport = `
-- go.mod --
module mod.com

-- main.go --
package main

var _ = x.X
-- x/x.go --
package x

var X = 0
`
	runner.Run(t, missingImport, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		env.OrganizeImports("main.go")
		env.Await(EmptyDiagnostics("main.go"))
	}, WithEditorConfig(fake.EditorConfig{Env: []string{"GOFLAGS=-tags=foo"}}))
}

// Tests golang/go#38467.
func TestNoSuggestedFixesForGeneratedFiles_Issue38467(t *testing.T) {
	const generated = `
-- go.mod --
module mod.com

-- main.go --
package main

// Code generated by generator.go. DO NOT EDIT.

func _() {
	for i, _ := range []string{} {
		_ = i
	}
}
`
	runner.Run(t, generated, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		original := env.ReadWorkspaceFile("main.go")
		metBy := env.Await(
			DiagnosticAt("main.go", 5, 8),
		)
		d, ok := metBy[0].(*protocol.PublishDiagnosticsParams)
		if !ok {
			t.Fatalf("unexpected met by result %v (%T)", metBy, metBy)
		}
		// Apply fixes and save the buffer.
		env.ApplyQuickFixes("main.go", d.Diagnostics)
		env.SaveBuffer("main.go")
		fixed := env.ReadWorkspaceFile("main.go")
		if original != fixed {
			t.Fatalf("generated file was changed by quick fixes:\n%s", tests.Diff(original, fixed))
		}
	})
}

// Expect a module/GOPATH error if there is an error in the file at startup.
// Tests golang/go#37279.
func TestShowMessage_Issue37279(t *testing.T) {
	const noModule = `
-- a.go --
package foo

func f() {
	fmt.Printl()
}
`
	runner.Run(t, noModule, func(t *testing.T, env *Env) {
		env.OpenFile("a.go")
		env.Await(env.DiagnosticAtRegexp("a.go", "fmt.Printl"), SomeShowMessage(""))
	})
}

// Expect no module/GOPATH error if there is no error in the file.
// Tests golang/go#37279.
func TestNoShowMessage_Issue37279(t *testing.T) {
	const noModule = `
-- a.go --
package foo

func f() {
}
`
	runner.Run(t, noModule, func(t *testing.T, env *Env) {
		env.OpenFile("a.go")
		env.Await(
			OnceMet(
				CompletedWork(lsp.DiagnosticWorkTitle(lsp.FromDidOpen), 1),
				NoDiagnostics("a.go"),
			),
			EmptyShowMessage(""),
		)
		// introduce an error, expect no Show Message
		env.RegexpReplace("a.go", "func", "fun")
		env.Await(env.DiagnosticAtRegexp("a.go", "fun"), EmptyShowMessage(""))
	})
}

// Tests golang/go#38602.
func TestNonexistentFileDiagnostics_Issue38602(t *testing.T) {
	const collision = `
-- x/x.go --
package x

import "x/hello"

func Hello() {
	hello.HiThere()
}
-- x/main.go --
package main

func main() {
	fmt.Println("")
}
`
	runner.Run(t, collision, func(t *testing.T, env *Env) {
		env.OpenFile("x/main.go")
		env.Await(
			env.DiagnosticAtRegexp("x/main.go", "fmt.Println"),
		)
		env.OrganizeImports("x/main.go")
		// span.Parse misparses the error message when multiple packages are
		// defined in the same directory, creating a garbage filename.
		// Previously, we would send diagnostics for this nonexistent file.
		// This test checks that we don't send diagnostics for this file.
		dir, err := os.Getwd()
		if err != nil {
			t.Fatal(err)
		}
		badFile := fmt.Sprintf("%s/found packages main (main.go) and x (x.go) in %s/src/x", dir, env.Sandbox.GOPATH())
		env.Await(
			OnceMet(
				CompletedWork(lsp.DiagnosticWorkTitle(lsp.FromDidChange), 1),
				EmptyDiagnostics("x/main.go"),
			),
			NoDiagnostics(badFile),
		)
	}, InGOPATH())
}

const ardanLabsProxy = `
-- github.com/ardanlabs/conf@v1.2.3/go.mod --
module github.com/ardanlabs/conf

go 1.12
-- github.com/ardanlabs/conf@v1.2.3/conf.go --
package conf

var ErrHelpWanted error
`

// Test for golang/go#38211.
func Test_Issue38211(t *testing.T) {
	testenv.NeedsGo1Point(t, 14)
	const ardanLabs = `
-- go.mod --
module mod.com

go 1.14
-- main.go --
package main

import "github.com/ardanlabs/conf"

func main() {
	_ = conf.ErrHelpWanted
}
`
	runner.Run(t, ardanLabs, func(t *testing.T, env *Env) {
		// Expect a diagnostic with a suggested fix to add
		// "github.com/ardanlabs/conf" to the go.mod file.
		env.OpenFile("go.mod")
		env.OpenFile("main.go")
		metBy := env.Await(
			env.DiagnosticAtRegexp("main.go", `"github.com/ardanlabs/conf"`),
		)
		d, ok := metBy[0].(*protocol.PublishDiagnosticsParams)
		if !ok {
			t.Fatalf("unexpected type for metBy (%T)", metBy)
		}
		env.ApplyQuickFixes("main.go", d.Diagnostics)
		env.SaveBuffer("go.mod")
		env.Await(
			EmptyDiagnostics("main.go"),
		)
		// Comment out the line that depends on conf and expect a
		// diagnostic and a fix to remove the import.
		env.RegexpReplace("main.go", "_ = conf.ErrHelpWanted", "//_ = conf.ErrHelpWanted")
		env.Await(
			env.DiagnosticAtRegexp("main.go", `"github.com/ardanlabs/conf"`),
		)
		env.SaveBuffer("main.go")
		// Expect a diagnostic and fix to remove the dependency in the go.mod.
		metBy = env.Await(
			EmptyDiagnostics("main.go"),
			env.DiagnosticAtRegexp("go.mod", "require github.com/ardanlabs/conf"),
		)
		d, ok = metBy[1].(*protocol.PublishDiagnosticsParams)
		if !ok {
			t.Fatalf("unexpected type for metBy (%T)", metBy)
		}
		env.ApplyQuickFixes("go.mod", d.Diagnostics)
		env.SaveBuffer("go.mod")
		env.Await(
			EmptyDiagnostics("go.mod"),
		)
		// Uncomment the lines and expect a new diagnostic for the import.
		env.RegexpReplace("main.go", "//_ = conf.ErrHelpWanted", "_ = conf.ErrHelpWanted")
		env.SaveBuffer("main.go")
		env.Await(
			env.DiagnosticAtRegexp("main.go", `"github.com/ardanlabs/conf"`),
		)
	}, WithProxy(ardanLabsProxy))
}

// Test for golang/go#38207.
func TestNewModule_Issue38207(t *testing.T) {
	testenv.NeedsGo1Point(t, 14)
	const emptyFile = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
`
	runner.Run(t, emptyFile, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		env.OpenFile("go.mod")
		env.EditBuffer("main.go", fake.NewEdit(0, 0, 0, 0, `package main

import "github.com/ardanlabs/conf"

func main() {
	_ = conf.ErrHelpWanted
}
`))
		env.SaveBuffer("main.go")
		metBy := env.Await(
			env.DiagnosticAtRegexp("main.go", `"github.com/ardanlabs/conf"`),
		)
		d, ok := metBy[0].(*protocol.PublishDiagnosticsParams)
		if !ok {
			t.Fatalf("unexpected type for diagnostics (%T)", d)
		}
		env.ApplyQuickFixes("main.go", d.Diagnostics)
		env.Await(
			EmptyDiagnostics("main.go"),
		)
	}, WithProxy(ardanLabsProxy))
}

// Test for golang/go#36960.
func TestNewFileBadImports_Issue36960(t *testing.T) {
	testenv.NeedsGo1Point(t, 14)
	const simplePackage = `
-- go.mod --
module mod.com

go 1.14
-- a/a1.go --
package a

import "fmt"

func _() {
	fmt.Println("hi")
}
`
	runner.Run(t, simplePackage, func(t *testing.T, env *Env) {
		env.OpenFile("a/a1.go")
		env.CreateBuffer("a/a2.go", ``)
		if err := env.Editor.SaveBufferWithoutActions(env.Ctx, "a/a2.go"); err != nil {
			t.Fatal(err)
		}
		env.Await(
			OnceMet(
				CompletedWork(lsp.DiagnosticWorkTitle(lsp.FromDidSave), 1),
				NoDiagnostics("a/a1.go"),
			),
		)
		env.EditBuffer("a/a2.go", fake.NewEdit(0, 0, 0, 0, `package a`))
		env.Await(
			OnceMet(
				CompletedWork(lsp.DiagnosticWorkTitle(lsp.FromDidChange), 1),
				NoDiagnostics("a/a1.go"),
			),
		)
	})
}

// This test tries to replicate the workflow of a user creating a new x test.
// It also tests golang/go#39315.
func TestManuallyCreatingXTest(t *testing.T) {
	// Only for 1.15 because of golang/go#37971.
	testenv.NeedsGo1Point(t, 15)

	// Create a package that already has a test variant (in-package test).
	const testVariant = `
-- go.mod --
module mod.com

go 1.15
-- hello/hello.go --
package hello

func Hello() {
	var x int
}
-- hello/hello_test.go --
package hello

import "testing"

func TestHello(t *testing.T) {
	var x int
	Hello()
}
`
	runner.Run(t, testVariant, func(t *testing.T, env *Env) {
		// Open the file, triggering the workspace load.
		// There are errors in the code to ensure all is working as expected.
		env.OpenFile("hello/hello.go")
		env.Await(
			env.DiagnosticAtRegexp("hello/hello.go", "x"),
			env.DiagnosticAtRegexp("hello/hello_test.go", "x"),
		)

		// Create an empty file with the intention of making it an x test.
		// This resembles a typical flow in an editor like VS Code, in which
		// a user would create an empty file and add content, saving
		// intermittently.
		// TODO(rstambler): There might be more edge cases here, as file
		// content can be added incrementally.
		env.CreateBuffer("hello/hello_x_test.go", ``)

		// Save the empty file (no actions since formatting will fail).
		env.Editor.SaveBufferWithoutActions(env.Ctx, "hello/hello_x_test.go")

		// Add the content. The missing import is for the package under test.
		env.EditBuffer("hello/hello_x_test.go", fake.NewEdit(0, 0, 0, 0, `package hello_test

import (
	"testing"
)

func TestHello(t *testing.T) {
	hello.Hello()
}
`))
		// Expect a diagnostic for the missing import. Save, which should
		// trigger import organization. The diagnostic should clear.
		env.Await(
			env.DiagnosticAtRegexp("hello/hello_x_test.go", "hello.Hello"),
		)
		env.SaveBuffer("hello/hello_x_test.go")
		env.Await(
			EmptyDiagnostics("hello/hello_x_test.go"),
		)
	})
}

func TestIgnoredFiles(t *testing.T) {
	const ws = `
-- go.mod --
module mod.com

go 1.15
-- _foo/x.go --
package x

var _ = foo.Bar
`
	runner.Run(t, ws, func(t *testing.T, env *Env) {
		env.OpenFile("_foo/x.go")
		env.Await(
			OnceMet(
				CompletedWork(lsp.DiagnosticWorkTitle(lsp.FromDidOpen), 1),
				NoDiagnostics("_foo/x.go"),
			))
	})
}

// Partially reproduces golang/go#38977, moving a file between packages.
// It also gets hit by some go command bug fixed in 1.15, but we don't
// care about that so much here.
func TestDeletePackage(t *testing.T) {
	const ws = `
-- go.mod --
module mod.com

go 1.15
-- a/a.go --
package a

const A = 1

-- b/b.go --
package b

import "mod.com/a"

const B = a.A

-- c/c.go --
package c

import "mod.com/a"

const C = a.A
`
	runner.Run(t, ws, func(t *testing.T, env *Env) {
		env.OpenFile("b/b.go")
		env.Await(CompletedWork(lsp.DiagnosticWorkTitle(lsp.FromDidOpen), 1))
		// Delete c/c.go, the only file in package c.
		env.RemoveWorkspaceFile("c/c.go")

		// We should still get diagnostics for files that exist.
		env.RegexpReplace("b/b.go", `a.A`, "a.Nonexistant")
		env.Await(env.DiagnosticAtRegexp("b/b.go", `Nonexistant`))
	})
}

// This is a copy of the scenario_default/quickfix_empty_files.txt test from
// govim. Reproduces golang/go#39646.
func TestQuickFixEmptyFiles(t *testing.T) {
	const mod = `
-- go.mod --
module mod.com

go 1.12
`
	runner.Run(t, mod, func(t *testing.T, env *Env) {
		// To fully recreate the govim tests, we create files by inserting
		// a newline, adding to the file, and then deleting the newline.
		// Wait for each event to process to avoid cancellations.
		writeGoVim := func(name, content string) {
			env.OpenFileWithContent(name, "\n")
			env.Await(CompletedWork(lsp.DiagnosticWorkTitle(lsp.FromDidOpen), 1))

			env.EditBuffer(name, fake.NewEdit(1, 0, 1, 0, content))
			env.Await(env.AnyDiagnosticAtCurrentVersion(name))

			env.EditBuffer(name, fake.NewEdit(0, 0, 1, 0, ""))
			env.Await(CompletedWork(lsp.DiagnosticWorkTitle(lsp.FromDidChange), 1))
		}
		writeGoVim("p/p.go", `package p


func DoIt(s string) {
	var x int
}
`)
		writeGoVim("main.go", `package main

import "mod.com/p"

func main() {
	p.DoIt(5)
}
`)
		writeGoVim("p/p_test.go", `package p

import "testing"

func TestDoIt(t *testing.T) {
	DoIt(5)
}
`)
		writeGoVim("p/x_test.go", `package p_test

import (
	"testing"

	"mod.com/p"
)

func TestDoIt(t *testing.T) {
	p.DoIt(5)
}
`)
		env.Await(
			env.DiagnosticAtRegexp("main.go", "5"),
			env.DiagnosticAtRegexp("p/p_test.go", "5"),
			env.DiagnosticAtRegexp("p/x_test.go", "5"),
		)
		env.RegexpReplace("p/p.go", "s string", "i int")
		env.Await(
			EmptyDiagnostics("main.go"),
			EmptyDiagnostics("p/p_test.go"),
			EmptyDiagnostics("p/x_test.go"),
		)
	})
}