vpython/venv/venv_test.go - infra/luci/luci-go - Git at Google

 // Copyright 2017 The LUCI Authors.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //      http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 package venv

 import (
 	"context"
 	"encoding/json"
 	"flag"
 	"fmt"
 	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strings"
 	"testing"

 	"go.chromium.org/luci/vpython/api/vpython"
 	"go.chromium.org/luci/vpython/python"

 	"go.chromium.org/luci/common/errors"
 	"go.chromium.org/luci/common/logging"
 	"go.chromium.org/luci/common/logging/gologger"
 	"go.chromium.org/luci/common/sync/parallel"
 	"go.chromium.org/luci/common/system/environ"
 	"go.chromium.org/luci/common/system/filesystem"

 	. "github.com/smartystreets/goconvey/convey"
 	. "go.chromium.org/luci/common/testing/assertions"
 )

 var verbose = flag.Bool("test.gologger", false, "Enable Go logging.")

 func testContext() context.Context {
 	c := context.Background()
 	if *verbose {
 		c = gologger.StdConfig.Use(c)
 		c = logging.SetLevel(c, logging.Debug)
 	}
 	return c
 }

 type resolvedInterpreter struct {
 	py      *python.Interpreter
 	version python.Version
 }

 func resolveFromPath(vers python.Version) *resolvedInterpreter {
 	c := testContext()
 	py, err := python.Find(c, vers, nil)
 	if err != nil {
 		return nil
 	}
 	if err := filesystem.AbsPath(&py.Python); err != nil {
 		panic(err)
 	}

 	ri := resolvedInterpreter{
 		py: py,
 	}
 	if ri.version, err = ri.py.GetVersion(c); err != nil {
 		panic(err)
 	}
 	return &ri
 }

 var (
 	pythonGeneric = resolveFromPath(python.Version{})
 	python27      = resolveFromPath(python.Version{Major: 2, Minor: 7, Patch: 0})
 	python3       = resolveFromPath(python.Version{Major: 3, Minor: 0, Patch: 0})
 )

 func TestResolvePythonInterpreter(t *testing.T) {
 	t.Parallel()

 	// This test is run for each resolved Python interpreter found on the host
 	// system.
 	testPythonInterpreter := func(c C, ctx context.Context, ri *resolvedInterpreter, vers string) {
 		cfg := Config{}
 		s := vpython.Spec{
 			PythonVersion: vers,
 		}

 		c.Convey(`Can resolve interpreter version`, func() {
 			So(cfg.resolvePythonInterpreter(ctx, &s), ShouldBeNil)
 			So(cfg.si.Python, ShouldEqual, ri.py.Python)

 			vers, err := python.ParseVersion(s.PythonVersion)
 			So(err, ShouldBeNil)
 			So(vers.IsSatisfiedBy(ri.version), ShouldBeTrue)
 		})

 		c.Convey(`Can resolve Runtime information`, func() {
 			var r vpython.Runtime
 			err := fillRuntime(ctx, ri.py, &r)
 			So(err, ShouldBeNil)
 			So(r.Path, ShouldNotEqual, "")
 			So(r.Prefix, ShouldNotEqual, "")
 			So(r.Hash, ShouldNotEqual, "")
 		})

 		c.Convey(fmt.Sprintf(`Fails when Python 9999 is requested, but a Python %s interpreter is forced.`, vers), func() {
 			cfg.Python = []string{ri.py.Python}
 			s.PythonVersion = "9999"
 			So(cfg.resolvePythonInterpreter(ctx, &s), ShouldErrLike, "none of [", "] matched specification")
 		})
 	}

 	Convey(`Resolving a Python interpreter`, t, func() {
 		ctx := testContext()

 		// Tests to run if we have Python 2.7 installed.
 		if python27 != nil {
 			Convey(`When Python 2.7 is requested`, func(c C) {
 				testPythonInterpreter(c, ctx, python27, "2.7")
 			})
 		}

 		// Tests to run if we have Python 2.7 and a generic Python installed.
 		if pythonGeneric != nil && python27 != nil {
 			// Our generic Python resolves to a known version, so we can proceed.
 			Convey(`When no Python version is specified, spec resolves to generic.`, func() {
 				cfg := Config{}
 				s := vpython.Spec{}
 				So(cfg.resolvePythonInterpreter(ctx, &s), ShouldBeNil)
 				So(cfg.si.Python, ShouldEqual, pythonGeneric.py.Python)

 				vers, err := python.ParseVersion(s.PythonVersion)
 				So(err, ShouldBeNil)
 				So(vers.IsSatisfiedBy(pythonGeneric.version), ShouldBeTrue)
 			})
 		}

 		// Tests to run if we have Python 3 installed.
 		if python3 != nil {
 			Convey(`When Python 3 is requested`, func(c C) {
 				testPythonInterpreter(c, ctx, python3, "3")
 			})
 		}
 	})

 	Convey(`Resolving interpreter from multiple options`, t, func() {
 		ctx := testContext()

 		pythons := []*resolvedInterpreter{}
 		tryAddPython := func(majorVersion, minorVersion int) {
 			ri := resolveFromPath(python.Version{majorVersion, minorVersion, 0})

 			// Ignore interpreters without '.' in the filename. Such binaries
 			// are usually just symlinks to binaries named with the specific
 			// minor version (e.g. "python3.9"), and if we don't ignore them we
 			// can end up with duplicate entries.
 			if ri != nil && strings.Contains(ri.py.Python, ".") {
 				pythons = append(pythons, ri)
 			}
 		}

 		tryAddPython(2, 7)
 		for v := 5; v < 20; v += 1 {
 			tryAddPython(3, v)
 		}

 		if len(pythons) < 2 {
 			// These tests aren't meaningful if we don't have at least two
 			// Python interpreters to test with.
 			return
 		}

 		Convey(`First interpreter in slice is selected by default`, func() {
 			for i := 0; i < len(pythons); i += 1 {
 				cfgPythons := SliceFlag{pythons[i].py.Python}
 				for j := 0; j < len(pythons); j += 1 {
 					if i != j {
 						cfgPythons = append(cfgPythons, pythons[j].py.Python)
 					}
 				}

 				cfg := Config{Python: cfgPythons}

 				// No Python version specified in the spec, so we should default
 				// to the first interpreter from the config.
 				s := vpython.Spec{}
 				So(cfg.resolvePythonInterpreter(ctx, &s), ShouldBeNil)
 				So(cfg.si.Python, ShouldEqual, cfgPythons[0])
 			}
 		})

 		Convey(`Spec selects matching Python interpreter from config`, func() {
 			cfgPythons := SliceFlag{}
 			for _, ri := range pythons {
 				cfgPythons = append(cfgPythons, ri.py.Python)
 			}

 			for _, ri := range pythons {
 				cfg := Config{Python: cfgPythons}

 				// Python version specified in the spec, so we should select
 				// the matching interpreter from the config.
 				s := vpython.Spec{
 					PythonVersion: fmt.Sprintf("%d.%d", ri.version.Major, ri.version.Minor),
 				}
 				So(cfg.resolvePythonInterpreter(ctx, &s), ShouldBeNil)
 				So(cfg.si.Python, ShouldEqual, ri.py.Python)
 			}
 		})
 	})
 }

 type setupCheckManifest struct {
 	Interpreter string `json:"interpreter"`
 	Pants       string `json:"pants"`
 	Shirt       string `json:"shirt"`
 }

 func testVirtualEnvWith(t *testing.T, ri *resolvedInterpreter) {
 	t.Parallel()

 	if ri == nil {
 		t.Skipf("No python interpreter found.")
 	}

 	tl, err := loadTestEnvironment(testContext(), t)
 	if err != nil {
 		t.Fatalf("could not set up test loader for %q: %s", ri.py.Python, err)
 	}

 	Convey(`Testing the VirtualEnv`, t, func() {
 		tdir := t.TempDir()
 		defer func() {
 			So(filesystem.RemoveAll(tdir), ShouldBeNil)
 		}()
 		c := testContext()

 		// Load the bootstrap wheels for the next part of the test.
 		So(tl.ensureWheels(c, t, ri.py, tdir), ShouldBeNil)

 		config := Config{
 			BaseDir:    tdir,
 			MaxHashLen: 4,
 			SetupEnv:   environ.System(),
 			Package: vpython.Spec_Package{
 				Name:    "foo/bar/virtualenv",
 				Version: "unresolved",
 			},
 			Python: []string{ri.py.Python},
 			Loader: tl,
 			Spec: &vpython.Spec{
 				Wheel: []*vpython.Spec_Package{
 					{Name: "foo/bar/shirt", Version: "unresolved"},
 					{Name: "foo/bar/pants", Version: "unresolved"},
 				},
 			},
 		}

 		Convey(`Testing Setup`, func() {
 			config.FailIfLocked = true
 			err := With(c, config, func(c context.Context, v *Env) error {
 				testScriptTarget := python.ScriptTarget{
 					Path: filepath.Join(testDataDir, "setup_check.py"),
 				}
 				checkOut := filepath.Join(tdir, "output.json")
 				cmd := v.Interpreter().MkIsolatedCommand(c, testScriptTarget, "--json-output", checkOut)
 				defer cmd.Cleanup()
 				cmd.Dir = "" // we want cwd
 				So(cmd.Run(), ShouldBeNil)

 				var m setupCheckManifest
 				So(loadJSON(checkOut, &m), ShouldBeNil)
 				So(m.Interpreter, ShouldStartWith, v.Root)
 				So(m.Pants, ShouldStartWith, v.Root)
 				So(m.Shirt, ShouldStartWith, v.Root)
 				So(v.Environment, ShouldNotBeNil)

 				// We should be able to load its environment stamp.
 				v.Environment = nil
 				So(v.AssertCompleteAndLoad(), ShouldBeNil)
 				So(v.Environment, ShouldNotBeNil)
 				So(len(v.Environment.Pep425Tag), ShouldBeGreaterThan, 0)
 				So(v.Environment.Spec, ShouldNotBeNil)
 				So(len(v.Environment.Spec.Wheel), ShouldEqual, len(config.Spec.Wheel))
 				So(v.Environment.Spec.Virtualenv, ShouldNotBeNil)
 				So(v.Environment.Spec.PythonVersion, ShouldNotEqual, "")

 				return nil
 			})
 			So(err, ShouldBeNil)

 			// We should be able to delete it.
 			v, err := config.makeEnv(c, nil)
 			So(err, ShouldBeNil)

 			So(v.Delete(c), ShouldBeNil)
 			So(v.Root, shouldNotExist)
 			So(v.lockPath, shouldNotExist)
 		})

 		Convey(`Testing new environment setup race`, func() {
 			const workers = 4

 			envs := make([]*vpython.Environment, workers)
 			err := parallel.FanOutIn(func(taskC chan<- func() error) {
 				for i := 0; i < workers; i++ {
 					i := i

 					taskC <- func() error {
 						return With(c, config, func(c context.Context, v *Env) error {
 							// Has successfully loaded an Environment.
 							envs[i] = v.Environment

 							// Can use the Python interpreter.
 							if _, err := v.Interpreter().GetVersion(c); err != nil {
 								return err
 							}
 							return nil
 						})
 					}
 				}
 			})
 			So(err, ShouldBeNil)

 			// All Environments must be equal.
 			var archetype *vpython.Environment
 			for _, env := range envs {
 				if archetype == nil {
 					archetype = env
 				} else {
 					So(env, ShouldResembleProto, archetype)
 				}
 			}
 		})
 	})
 }

 func TestVirtualEnv(t *testing.T) {
 	// TODO(crbug/1060092): fix and re-enable the test.
 	t.Skip("flaky, see https://crbug.com/1060092")
 	t.Parallel()

 	for _, tc := range []struct {
 		name string
 		ri   *resolvedInterpreter
 	}{
 		{"python27", python27},
 		{"python3", python3},
 	} {
 		tc := tc

 		t.Run(fmt.Sprintf(`Testing Virtualenv for: %s`, tc.name), func(t *testing.T) {
 			testVirtualEnvWith(t, tc.ri)
 		})
 	}
 }

 func loadJSON(path string, dst interface{}) error {
 	content, err := ioutil.ReadFile(path)
 	if err != nil {
 		return errors.Annotate(err, "failed to open file").Err()
 	}
 	if err := json.Unmarshal(content, dst); err != nil {
 		return errors.Annotate(err, "failed to unmarshal JSON").Err()
 	}
 	return nil
 }

 func shouldNotExist(actual interface{}, expected ...interface{}) string {
 	path := actual.(string)
 	switch _, err := os.Stat(path); {
 	case err == nil:
 		return fmt.Sprintf("Path %q should not exist, but it does.", path)
 	case os.IsNotExist(err):
 		return ""
 	default:
 		return fmt.Sprintf("Couldn't check if %q exists: %s", path, err)
 	}
 }
	// Copyright 2017 The LUCI Authors.
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	package venv

	import (
	"context"
	"encoding/json"
	"flag"
	"fmt"
	"io/ioutil"
	"os"
	"path/filepath"
	"strings"
	"testing"

	"go.chromium.org/luci/vpython/api/vpython"
	"go.chromium.org/luci/vpython/python"

	"go.chromium.org/luci/common/errors"
	"go.chromium.org/luci/common/logging"
	"go.chromium.org/luci/common/logging/gologger"
	"go.chromium.org/luci/common/sync/parallel"
	"go.chromium.org/luci/common/system/environ"
	"go.chromium.org/luci/common/system/filesystem"

	. "github.com/smartystreets/goconvey/convey"
	. "go.chromium.org/luci/common/testing/assertions"
	)

	var verbose = flag.Bool("test.gologger", false, "Enable Go logging.")

	func testContext() context.Context {
	c := context.Background()
	if *verbose {
	c = gologger.StdConfig.Use(c)
	c = logging.SetLevel(c, logging.Debug)
	}
	return c
	}

	type resolvedInterpreter struct {
	py *python.Interpreter
	version python.Version
	}

	func resolveFromPath(vers python.Version) *resolvedInterpreter {
	c := testContext()
	py, err := python.Find(c, vers, nil)
	if err != nil {
	return nil
	}
	if err := filesystem.AbsPath(&py.Python); err != nil {
	panic(err)
	}

	ri := resolvedInterpreter{
	py: py,
	}
	if ri.version, err = ri.py.GetVersion(c); err != nil {
	panic(err)
	}
	return &ri
	}

	var (
	pythonGeneric = resolveFromPath(python.Version{})
	python27 = resolveFromPath(python.Version{Major: 2, Minor: 7, Patch: 0})
	python3 = resolveFromPath(python.Version{Major: 3, Minor: 0, Patch: 0})
	)

	func TestResolvePythonInterpreter(t *testing.T) {
	t.Parallel()

	// This test is run for each resolved Python interpreter found on the host
	// system.
	testPythonInterpreter := func(c C, ctx context.Context, ri *resolvedInterpreter, vers string) {
	cfg := Config{}
	s := vpython.Spec{
	PythonVersion: vers,
	}

	c.Convey(`Can resolve interpreter version`, func() {
	So(cfg.resolvePythonInterpreter(ctx, &s), ShouldBeNil)
	So(cfg.si.Python, ShouldEqual, ri.py.Python)

	vers, err := python.ParseVersion(s.PythonVersion)
	So(err, ShouldBeNil)
	So(vers.IsSatisfiedBy(ri.version), ShouldBeTrue)
	})

	c.Convey(`Can resolve Runtime information`, func() {
	var r vpython.Runtime
	err := fillRuntime(ctx, ri.py, &r)
	So(err, ShouldBeNil)
	So(r.Path, ShouldNotEqual, "")
	So(r.Prefix, ShouldNotEqual, "")
	So(r.Hash, ShouldNotEqual, "")
	})

	c.Convey(fmt.Sprintf(`Fails when Python 9999 is requested, but a Python %s interpreter is forced.`, vers), func() {
	cfg.Python = []string{ri.py.Python}
	s.PythonVersion = "9999"
	So(cfg.resolvePythonInterpreter(ctx, &s), ShouldErrLike, "none of [", "] matched specification")
	})
	}

	Convey(`Resolving a Python interpreter`, t, func() {
	ctx := testContext()

	// Tests to run if we have Python 2.7 installed.
	if python27 != nil {
	Convey(`When Python 2.7 is requested`, func(c C) {
	testPythonInterpreter(c, ctx, python27, "2.7")
	})
	}

	// Tests to run if we have Python 2.7 and a generic Python installed.
	if pythonGeneric != nil && python27 != nil {
	// Our generic Python resolves to a known version, so we can proceed.
	Convey(`When no Python version is specified, spec resolves to generic.`, func() {
	cfg := Config{}
	s := vpython.Spec{}
	So(cfg.resolvePythonInterpreter(ctx, &s), ShouldBeNil)
	So(cfg.si.Python, ShouldEqual, pythonGeneric.py.Python)

	vers, err := python.ParseVersion(s.PythonVersion)
	So(err, ShouldBeNil)
	So(vers.IsSatisfiedBy(pythonGeneric.version), ShouldBeTrue)
	})
	}

	// Tests to run if we have Python 3 installed.
	if python3 != nil {
	Convey(`When Python 3 is requested`, func(c C) {
	testPythonInterpreter(c, ctx, python3, "3")
	})
	}
	})

	Convey(`Resolving interpreter from multiple options`, t, func() {
	ctx := testContext()

	pythons := []*resolvedInterpreter{}
	tryAddPython := func(majorVersion, minorVersion int) {
	ri := resolveFromPath(python.Version{majorVersion, minorVersion, 0})

	// Ignore interpreters without '.' in the filename. Such binaries
	// are usually just symlinks to binaries named with the specific
	// minor version (e.g. "python3.9"), and if we don't ignore them we
	// can end up with duplicate entries.
	if ri != nil && strings.Contains(ri.py.Python, ".") {
	pythons = append(pythons, ri)
	}
	}

	tryAddPython(2, 7)
	for v := 5; v < 20; v += 1 {
	tryAddPython(3, v)
	}

	if len(pythons) < 2 {
	// These tests aren't meaningful if we don't have at least two
	// Python interpreters to test with.
	return
	}

	Convey(`First interpreter in slice is selected by default`, func() {
	for i := 0; i < len(pythons); i += 1 {
	cfgPythons := SliceFlag{pythons[i].py.Python}
	for j := 0; j < len(pythons); j += 1 {
	if i != j {
	cfgPythons = append(cfgPythons, pythons[j].py.Python)
	}
	}

	cfg := Config{Python: cfgPythons}

	// No Python version specified in the spec, so we should default
	// to the first interpreter from the config.
	s := vpython.Spec{}
	So(cfg.resolvePythonInterpreter(ctx, &s), ShouldBeNil)
	So(cfg.si.Python, ShouldEqual, cfgPythons[0])
	}
	})

	Convey(`Spec selects matching Python interpreter from config`, func() {
	cfgPythons := SliceFlag{}
	for _, ri := range pythons {
	cfgPythons = append(cfgPythons, ri.py.Python)
	}

	for _, ri := range pythons {
	cfg := Config{Python: cfgPythons}

	// Python version specified in the spec, so we should select
	// the matching interpreter from the config.
	s := vpython.Spec{
	PythonVersion: fmt.Sprintf("%d.%d", ri.version.Major, ri.version.Minor),
	}
	So(cfg.resolvePythonInterpreter(ctx, &s), ShouldBeNil)
	So(cfg.si.Python, ShouldEqual, ri.py.Python)
	}
	})
	})
	}

	type setupCheckManifest struct {
	Interpreter string `json:"interpreter"`
	Pants string `json:"pants"`
	Shirt string `json:"shirt"`
	}

	func testVirtualEnvWith(t testing.T, ri resolvedInterpreter) {
	t.Parallel()

	if ri == nil {
	t.Skipf("No python interpreter found.")
	}

	tl, err := loadTestEnvironment(testContext(), t)
	if err != nil {
	t.Fatalf("could not set up test loader for %q: %s", ri.py.Python, err)
	}

	Convey(`Testing the VirtualEnv`, t, func() {
	tdir := t.TempDir()
	defer func() {
	So(filesystem.RemoveAll(tdir), ShouldBeNil)
	}()
	c := testContext()

	// Load the bootstrap wheels for the next part of the test.
	So(tl.ensureWheels(c, t, ri.py, tdir), ShouldBeNil)

	config := Config{
	BaseDir: tdir,
	MaxHashLen: 4,
	SetupEnv: environ.System(),
	Package: vpython.Spec_Package{
	Name: "foo/bar/virtualenv",
	Version: "unresolved",
	},
	Python: []string{ri.py.Python},
	Loader: tl,
	Spec: &vpython.Spec{
	Wheel: []*vpython.Spec_Package{
	{Name: "foo/bar/shirt", Version: "unresolved"},
	{Name: "foo/bar/pants", Version: "unresolved"},
	},
	},
	}

	Convey(`Testing Setup`, func() {
	config.FailIfLocked = true
	err := With(c, config, func(c context.Context, v *Env) error {
	testScriptTarget := python.ScriptTarget{
	Path: filepath.Join(testDataDir, "setup_check.py"),
	}
	checkOut := filepath.Join(tdir, "output.json")
	cmd := v.Interpreter().MkIsolatedCommand(c, testScriptTarget, "--json-output", checkOut)
	defer cmd.Cleanup()
	cmd.Dir = "" // we want cwd
	So(cmd.Run(), ShouldBeNil)

	var m setupCheckManifest
	So(loadJSON(checkOut, &m), ShouldBeNil)
	So(m.Interpreter, ShouldStartWith, v.Root)
	So(m.Pants, ShouldStartWith, v.Root)
	So(m.Shirt, ShouldStartWith, v.Root)
	So(v.Environment, ShouldNotBeNil)

	// We should be able to load its environment stamp.
	v.Environment = nil
	So(v.AssertCompleteAndLoad(), ShouldBeNil)
	So(v.Environment, ShouldNotBeNil)
	So(len(v.Environment.Pep425Tag), ShouldBeGreaterThan, 0)
	So(v.Environment.Spec, ShouldNotBeNil)
	So(len(v.Environment.Spec.Wheel), ShouldEqual, len(config.Spec.Wheel))
	So(v.Environment.Spec.Virtualenv, ShouldNotBeNil)
	So(v.Environment.Spec.PythonVersion, ShouldNotEqual, "")

	return nil
	})
	So(err, ShouldBeNil)

	// We should be able to delete it.
	v, err := config.makeEnv(c, nil)
	So(err, ShouldBeNil)

	So(v.Delete(c), ShouldBeNil)
	So(v.Root, shouldNotExist)
	So(v.lockPath, shouldNotExist)
	})

	Convey(`Testing new environment setup race`, func() {
	const workers = 4

	envs := make([]*vpython.Environment, workers)
	err := parallel.FanOutIn(func(taskC chan<- func() error) {
	for i := 0; i < workers; i++ {
	i := i

	taskC <- func() error {
	return With(c, config, func(c context.Context, v *Env) error {
	// Has successfully loaded an Environment.
	envs[i] = v.Environment

	// Can use the Python interpreter.
	if _, err := v.Interpreter().GetVersion(c); err != nil {
	return err
	}
	return nil
	})
	}
	}
	})
	So(err, ShouldBeNil)

	// All Environments must be equal.
	var archetype *vpython.Environment
	for _, env := range envs {
	if archetype == nil {
	archetype = env
	} else {
	So(env, ShouldResembleProto, archetype)
	}
	}
	})
	})
	}

	func TestVirtualEnv(t *testing.T) {
	// TODO(crbug/1060092): fix and re-enable the test.
	t.Skip("flaky, see https://crbug.com/1060092")
	t.Parallel()

	for _, tc := range []struct {
	name string
	ri *resolvedInterpreter
	}{
	{"python27", python27},
	{"python3", python3},
	} {
	tc := tc

	t.Run(fmt.Sprintf(`Testing Virtualenv for: %s`, tc.name), func(t *testing.T) {
	testVirtualEnvWith(t, tc.ri)
	})
	}
	}

	func loadJSON(path string, dst interface{}) error {
	content, err := ioutil.ReadFile(path)
	if err != nil {
	return errors.Annotate(err, "failed to open file").Err()
	}
	if err := json.Unmarshal(content, dst); err != nil {
	return errors.Annotate(err, "failed to unmarshal JSON").Err()
	}
	return nil
	}

	func shouldNotExist(actual interface{}, expected ...interface{}) string {
	path := actual.(string)
	switch _, err := os.Stat(path); {
	case err == nil:
	return fmt.Sprintf("Path %q should not exist, but it does.", path)
	case os.IsNotExist(err):
	return ""
	default:
	return fmt.Sprintf("Couldn't check if %q exists: %s", path, err)
	}
	}