update vendor

Signed-off-by: Daniel Nephin <dnephin@docker.com>

vendor/github.com/gotestyourself/gotestyourself/env/env.go

@@ -0,0 +1,92 @@
+/*Package env provides functions to test code that read environment variables
+or the current working directory.
+*/
+package env
+
+import (
+	"os"
+	"strings"
+
+	"github.com/gotestyourself/gotestyourself/assert"
+)
+
+type helperT interface {
+	Helper()
+}
+
+// Patch changes the value of an environment variable, and returns a
+// function which will reset the the value of that variable back to the
+// previous state.
+func Patch(t assert.TestingT, key, value string) func() {
+	if ht, ok := t.(helperT); ok {
+		ht.Helper()
+	}
+	oldValue, ok := os.LookupEnv(key)
+	assert.NilError(t, os.Setenv(key, value))
+	return func() {
+		if ht, ok := t.(helperT); ok {
+			ht.Helper()
+		}
+		if !ok {
+			assert.NilError(t, os.Unsetenv(key))
+			return
+		}
+		assert.NilError(t, os.Setenv(key, oldValue))
+	}
+}
+
+// PatchAll sets the environment to env, and returns a function which will
+// reset the environment back to the previous state.
+func PatchAll(t assert.TestingT, env map[string]string) func() {
+	if ht, ok := t.(helperT); ok {
+		ht.Helper()
+	}
+	oldEnv := os.Environ()
+	os.Clearenv()
+
+	for key, value := range env {
+		assert.NilError(t, os.Setenv(key, value))
+	}
+	return func() {
+		if ht, ok := t.(helperT); ok {
+			ht.Helper()
+		}
+		os.Clearenv()
+		for key, oldVal := range ToMap(oldEnv) {
+			assert.NilError(t, os.Setenv(key, oldVal))
+		}
+	}
+}
+
+// ToMap takes a list of strings in the format returned by os.Environ() and
+// returns a mapping of keys to values.
+func ToMap(env []string) map[string]string {
+	result := map[string]string{}
+	for _, raw := range env {
+		parts := strings.SplitN(raw, "=", 2)
+		switch len(parts) {
+		case 1:
+			result[raw] = ""
+		case 2:
+			result[parts[0]] = parts[1]
+		}
+	}
+	return result
+}
+
+// ChangeWorkingDir to the directory, and return a function which restores the
+// previous working directory.
+func ChangeWorkingDir(t assert.TestingT, dir string) func() {
+	if ht, ok := t.(helperT); ok {
+		ht.Helper()
+	}
+	cwd, err := os.Getwd()
+	assert.NilError(t, err)
+	assert.NilError(t, os.Chdir(dir))
+	return func() {
+		if ht, ok := t.(helperT); ok {
+			ht.Helper()
+		}
+		assert.NilError(t, os.Chdir(cwd))
+	}
+}