testscript

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 Go to latest Published: Aug 30, 2020 License: BSD-3-Clause Imports: 25 Imported by: 12

Documentation

Overview

Package testscript provides support for defining filesystem-based tests by creating scripts in a directory.

To invoke the tests, call testscript.Run. For example: 

func TestFoo(t *testing.T) {
	testscript.Run(t, testscript.Params{
		Dir: "testdata",
	})
}

A testscript directory holds test scripts *.txt run during 'go test'. Each script defines a subtest; the exact set of allowable commands in a script are defined by the parameters passed to the Run function. To run a specific script foo.txt 

go test cmd/go -run=TestName/^foo$

where TestName is the name of the test that Run is called from.

To define an executable command (or several) that can be run as part of the script, call RunMain with the functions that implement the command's functionality. The command functions will be called in a separate process, so are free to mutate global variables without polluting the top level test binary. 

func TestMain(m *testing.M) {
	os.Exit(testscript.RunMain(m, map[string] func() int{
		"testscript": testscriptMain,
	}))
}

In general script files should have short names: a few words, not whole sentences. The first word should be the general category of behavior being tested, often the name of a subcommand to be tested or a concept (vendor, pattern).

Each script is a text archive (go doc github.com/rogpeppe/go-internal/txtar). The script begins with an actual command script to run followed by the content of zero or more supporting files to create in the script's temporary file system before it starts executing.

As an example: 

# hello world
exec cat hello.text
stdout 'hello world\n'
! stderr .

-- hello.text --
hello world

Each script runs in a fresh temporary work directory tree, available to scripts as $WORK. Scripts also have access to these other environment variables: 

HOME=/no-home
PATH=<actual PATH>
TMPDIR=$WORK/tmp
devnull=<value of os.DevNull>
goversion=<current Go version; for example, 1.12>

The environment variable $exe (lowercase) is an empty string on most systems, ".exe" on Windows.

The script's supporting files are unpacked relative to $WORK and then the script begins execution in that directory as well. Thus the example above runs in $WORK with $WORK/hello.txt containing the listed contents.

The lines at the top of the script are a sequence of commands to be executed by a small script engine in the testscript package (not the system shell). The script stops and the overall test fails if any particular command fails.

Each line is parsed into a sequence of space-separated command words, with environment variable expansion and # marking an end-of-line comment. Adding single quotes around text keeps spaces in that text from being treated as word separators and also disables environment variable expansion. Inside a single-quoted block of text, a repeated single quote indicates a literal single quote, as in: 

'Don''t communicate by sharing memory.'

A line beginning with # is a comment and conventionally explains what is being done or tested at the start of a new phase in the script.

A special form of environment variable syntax can be used to quote regexp metacharacters inside environment variables. The "@R" suffix is special, and indicates that the variable should be quoted. 

${VAR@R}

The command prefix ! indicates that the command on the rest of the line (typically go or a matching predicate) must fail, not succeed. Only certain commands support this prefix. They are indicated below by [!] in the synopsis.

The command prefix [cond] indicates that the command on the rest of the line should only run when the condition is satisfied. The predefined conditions are:

  • [short] for testing.Short()
  • net for whether the external network can be used
  • [link] for whether the OS has hard link support
  • [symlink] for whether the OS has symbolic link support
  • [exec:prog] for whether prog is available for execution (found by exec.LookPath)

A condition can be negated: [!short] means to run the rest of the line when testing.Short() is false.

Additional conditions can be added by passing a function to Params.Condition.

The predefined commands are:

  • cd dir Change to the given directory for future commands.
  • chmod perm path... Change the permissions of the files or directories named by the path arguments to the given octal mode (000 to 777).
  • cmp file1 file2 Check that the named files have the same content. By convention, file1 is the actual data and file2 the expected data. File1 can be "stdout" or "stderr" to use the standard output or standard error from the most recent exec or wait command. (If the files have differing content, the failure prints a diff.)
  • cmpenv file1 file2 Like cmp, but environment variables in file2 are substituted before the comparison. For example, $GOOS is replaced by the target GOOS.
  • cp src... dst Copy the listed files to the target file or existing directory. src can include "stdout" or "stderr" to use the standard output or standard error from the most recent exec or go command.
  • env [key=value...] With no arguments, print the environment (useful for debugging). Otherwise add the listed key=value pairs to the environment.

  • [!] exec program [args...] [&] Run the given executable program with the arguments. It must (or must not) succeed. Note that 'exec' does not terminate the script (unlike in Unix shells).

    If the last token is '&', the program executes in the background. The standard output and standard error of the previous command is cleared, but the output of the background process is buffered — and checking of its exit status is delayed — until the next call to 'wait', 'skip', or 'stop' or the end of the test. At the end of the test, any remaining background processes are terminated using os.Interrupt (if supported) or os.Kill.

    Standard input can be provided using the stdin command; this will be cleared after exec has been called.

  • [!] exists [-readonly] file... Each of the listed files or directories must (or must not) exist. If -readonly is given, the files or directories must be unwritable.
  • [!] grep [-count=N] pattern file The file's content must (or must not) match the regular expression pattern. For positive matches, -count=N specifies an exact number of matches to require.
  • mkdir path... Create the listed directories, if they do not already exists.
  • rm file... Remove the listed files or directories.
  • skip [message] Mark the test skipped, including the message if given.
  • stdin file Set the standard input for the next exec command to the contents of the given file. File can be "stdout" or "stderr" to use the standard output or standard error from the most recent exec or wait command.
  • [!] stderr [-count=N] pattern Apply the grep command (see above) to the standard error from the most recent exec or wait command.
  • [!] stdout [-count=N] pattern Apply the grep command (see above) to the standard output from the most recent exec or wait command.
  • stop [message] Stop the test early (marking it as passing), including the message if given.
  • symlink file -> target Create file as a symlink to target. The -> (like in ls -l output) is required.
  • wait Wait for all 'exec' and 'go' commands started in the background (with the '&' token) to exit, and display success or failure status for them. After a call to wait, the 'stderr' and 'stdout' commands will apply to the concatenation of the corresponding streams of the background commands, in the order in which those commands were started.

When TestScript runs a script and the script fails, by default TestScript shows the execution of the most recent phase of the script (since the last # comment) and only shows the # comments for earlier phases. For example, here is a multi-phase script with a bug in it (TODO: make this example less go-command specific): 

# GOPATH with p1 in d2, p2 in d2
env GOPATH=$WORK/d1${:}$WORK/d2

# build & install p1
env
go install -i p1
! stale p1
! stale p2

# modify p2 - p1 should appear stale
cp $WORK/p2x.go $WORK/d2/src/p2/p2.go
stale p1 p2

# build & install p1 again
go install -i p11
! stale p1
! stale p2

-- $WORK/d1/src/p1/p1.go --
package p1
import "p2"
func F() { p2.F() }
-- $WORK/d2/src/p2/p2.go --
package p2
func F() {}
-- $WORK/p2x.go --
package p2
func F() {}
func G() {}

The bug is that the final phase installs p11 instead of p1. The test failure looks like: 

$ go test -run=Script
--- FAIL: TestScript (3.75s)
    --- FAIL: TestScript/install_rebuild_gopath (0.16s)
        script_test.go:223:
            # GOPATH with p1 in d2, p2 in d2 (0.000s)
            # build & install p1 (0.087s)
            # modify p2 - p1 should appear stale (0.029s)
            # build & install p1 again (0.022s)
            > go install -i p11
            [stderr]
            can't load package: package p11: cannot find package "p11" in any of:
            	/Users/rsc/go/src/p11 (from $GOROOT)
            	$WORK/d1/src/p11 (from $GOPATH)
            	$WORK/d2/src/p11
            [exit status 1]
            FAIL: unexpected go command failure

        script_test.go:73: failed at testdata/script/install_rebuild_gopath.txt:15 in $WORK/gopath/src

FAIL
exit status 1
FAIL	cmd/go	4.875s
$

Note that the commands in earlier phases have been hidden, so that the relevant commands are more easily found, and the elapsed time for a completed phase is shown next to the phase heading. To see the entire execution, use "go test -v", which also adds an initial environment dump to the beginning of the log.

Note also that in reported output, the actual name of the per-script temporary directory has been consistently replaced with the literal string $WORK.

If Params.TestWork is true, it causes each test to log the name of its $WORK directory and other environment variable settings and also to leave that directory behind when it exits, for manual debugging of failing tests: 

$ go test -run=Script -work
--- FAIL: TestScript (3.75s)
    --- FAIL: TestScript/install_rebuild_gopath (0.16s)
        script_test.go:223:
            WORK=/tmp/cmd-go-test-745953508/script-install_rebuild_gopath
            GOARCH=
            GOCACHE=/Users/rsc/Library/Caches/go-build
            GOOS=
            GOPATH=$WORK/gopath
            GOROOT=/Users/rsc/go
            HOME=/no-home
            TMPDIR=$WORK/tmp
            exe=

            # GOPATH with p1 in d2, p2 in d2 (0.000s)
            # build & install p1 (0.085s)
            # modify p2 - p1 should appear stale (0.030s)
            # build & install p1 again (0.019s)
            > go install -i p11
            [stderr]
            can't load package: package p11: cannot find package "p11" in any of:
            	/Users/rsc/go/src/p11 (from $GOROOT)
            	$WORK/d1/src/p11 (from $GOPATH)
            	$WORK/d2/src/p11
            [exit status 1]
            FAIL: unexpected go command failure

        script_test.go:73: failed at testdata/script/install_rebuild_gopath.txt:15 in $WORK/gopath/src

FAIL
exit status 1
FAIL	cmd/go	4.875s
$

$ WORK=/tmp/cmd-go-test-745953508/script-install_rebuild_gopath
$ cd $WORK/d1/src/p1
$ cat p1.go
package p1
import "p2"
func F() { p2.F() }
$

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

func IgnoreMissedCoverage 

func IgnoreMissedCoverage()

IgnoreMissedCoverage causes any missed coverage information (for example when a function passed to RunMain calls os.Exit, for example) to be ignored. This function should be called before calling RunMain.

func Run 

func Run(t *testing.T, p Params)

RunDir runs the tests in the given directory. All files in dir with a ".txt" are considered to be test files.

func RunMain 

func RunMain(m TestingM, commands map[string]func() int) (exitCode int)

RunMain should be called within a TestMain function to allow subcommands to be run in the testscript context.

The commands map holds the set of command names, each with an associated run function which should return the code to pass to os.Exit. It's OK for a command function to exit itself, but this may result in loss of coverage information.

When Run is called, these commands will be available as testscript commands; note that these commands behave like commands run with the "exec" command: they set stdout and stderr, and can be run in the background by passing "&" as a final argument.

This function returns an exit code to pass to os.Exit, after calling m.Run.

func RunT 

func RunT(t T, p Params)

RunT is like Run but uses an interface type instead of the concrete *testing.T type to make it possible to use testscript functionality outside of go test.

Types

type Env 

type Env struct {
	// WorkDir holds the path to the root directory of the
	// extracted files.
	WorkDir string
	// Vars holds the initial set environment variables that will be passed to the
	// testscript commands.
	Vars []string
	// Cd holds the initial current working directory.
	Cd string
	// Values holds a map of arbitrary values for use by custom
	// testscript commands. This enables Setup to pass arbitrary
	// values (not just strings) through to custom commands.
	Values map[interface{}]interface{}
	// contains filtered or unexported fields
}

Env holds the environment to use at the start of a test script invocation.

func (*Env) Defer added in v1.2.0 

func (e *Env) Defer(f func())

Defer arranges for f to be called at the end of the test. If Defer is called multiple times, the defers are executed in reverse order (similar to Go's defer statement)

func (*Env) Getenv added in v1.6.0 

func (e *Env) Getenv(key string) string

Getenv retrieves the value of the environment variable named by the key. It returns the value, which will be empty if the variable is not present.

func (*Env) Setenv added in v1.6.0 

func (e *Env) Setenv(key, value string)

Setenv sets the value of the environment variable named by the key. It panics if key is invalid.

func (*Env) T added in v1.6.0 

func (e *Env) T() T

T returns the t argument passed to the current test by the T.Run method. Note that if the tests were started by calling Run, the returned value will implement testing.TB. Note that, despite that, the underlying value will not be of type *testing.T because *testing.T does not implement T.

If Cleanup is called on the returned value, the function will run after any functions passed to Env.Defer.

type Params 

type Params struct {
	// Dir holds the name of the directory holding the scripts.
	// All files in the directory with a .txt suffix will be considered
	// as test scripts. By default the current directory is used.
	// Dir is interpreted relative to the current test directory.
	Dir string

	// Setup is called, if not nil, to complete any setup required
	// for a test. The WorkDir and Vars fields will have already
	// been initialized and all the files extracted into WorkDir,
	// and Cd will be the same as WorkDir.
	// The Setup function may modify Vars and Cd as it wishes.
	Setup func(*Env) error

	// Condition is called, if not nil, to determine whether a particular
	// condition is true. It's called only for conditions not in the
	// standard set, and may be nil.
	Condition func(cond string) (bool, error)

	// Cmds holds a map of commands available to the script.
	// It will only be consulted for commands not part of the standard set.
	Cmds map[string]func(ts *TestScript, neg bool, args []string)

	// TestWork specifies that working directories should be
	// left intact for later inspection.
	TestWork bool

	// WorkdirRoot specifies the directory within which scripts' work
	// directories will be created. Setting WorkdirRoot implies TestWork=true.
	// If empty, the work directories will be created inside
	// $GOTMPDIR/go-test-script*, where $GOTMPDIR defaults to os.TempDir().
	WorkdirRoot string

	// IgnoreMissedCoverage specifies that if coverage information
	// is being generated (with the -test.coverprofile flag) and a subcommand
	// function passed to RunMain fails to generate coverage information
	// (for example because the function invoked os.Exit), then the
	// error will be ignored.
	IgnoreMissedCoverage bool

	// UpdateScripts specifies that if a `cmp` command fails and its second
	// argument refers to a file inside the testscript file, the command will
	// succeed and the testscript file will be updated to reflect the actual
	// content (which could be stdout, stderr or a real file).
	//
	// The content will be quoted with txtar.Quote if needed;
	// a manual change will be needed if it is not unquoted in the
	// script.
	UpdateScripts bool
}

Params holds parameters for a call to Run.

type T 

type T interface {
	Skip(...interface{})
	Fatal(...interface{})
	Parallel()
	Log(...interface{})
	FailNow()
	Run(string, func(T))
	// Verbose is usually implemented by the testing package
	// directly rather than on the *testing.T type.
	Verbose() bool
}

T holds all the methods of the *testing.T type that are used by testscript.

type TestScript 

type TestScript struct {
	// contains filtered or unexported fields
}

A TestScript holds execution state for a single test script.

func (*TestScript) BackgroundCmds added in v1.2.0 

func (ts *TestScript) BackgroundCmds() []*exec.Cmd

BackgroundCmds returns a slice containing all the commands that have been started in the background since the most recent wait command, or the start of the script if wait has not been called.

func (*TestScript) Check 

func (ts *TestScript) Check(err error)

Check calls ts.Fatalf if err != nil.

func (*TestScript) Defer added in v1.2.0 

func (ts *TestScript) Defer(f func())

Defer arranges for f to be called at the end of the test. If Defer is called multiple times, the defers are executed in reverse order (similar to Go's defer statement)

func (*TestScript) Exec 

func (ts *TestScript) Exec(command string, args ...string) error

Exec runs the given command and saves its stdout and stderr so they can be inspected by subsequent script commands.

func (*TestScript) Fatalf 

func (ts *TestScript) Fatalf(format string, args ...interface{})

fatalf aborts the test with the given failure message.

func (*TestScript) Getenv 

func (ts *TestScript) Getenv(key string) string

Getenv gets the value of the environment variable named by the key.

func (*TestScript) Logf 

func (ts *TestScript) Logf(format string, args ...interface{})

Logf appends the given formatted message to the test log transcript.

func (*TestScript) MkAbs 

func (ts *TestScript) MkAbs(file string) string

MkAbs interprets file relative to the test script's current directory and returns the corresponding absolute path.

func (*TestScript) ReadFile added in v1.4.0 

func (ts *TestScript) ReadFile(file string) string

ReadFile returns the contents of the file with the given name, intepreted relative to the test script's current directory. It interprets "stdout" and "stderr" to mean the standard output or standard error from the most recent exec or wait command respectively.

If the file cannot be read, the script fails.

func (*TestScript) Setenv 

func (ts *TestScript) Setenv(key, value string)

Setenv sets the value of the environment variable named by the key.

func (*TestScript) Value added in v1.3.0 

func (ts *TestScript) Value(key interface{}) interface{}

Value returns a value from Env.Values, or nil if no value was set by Setup.

type TestingM 

type TestingM interface {
	Run() int
}

TestingM is implemented by *testing.M. It's defined as an interface to allow testscript to co-exist with other testing frameworks that might also wish to call M.Run.

Source Files

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