Vendor gotestyourself/env

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

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

@@ -0,0 +1,58 @@
+/*Package env provides functions to test code that read environment variables
+ */
+package env
+
+import (
+	"os"
+	"strings"
+
+	"github.com/stretchr/testify/require"
+)
+
+// 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 require.TestingT, key, value string) func() {
+	oldValue, ok := os.LookupEnv(key)
+	require.NoError(t, os.Setenv(key, value))
+	return func() {
+		if !ok {
+			require.NoError(t, os.Unsetenv(key))
+			return
+		}
+		require.NoError(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 require.TestingT, env map[string]string) func() {
+	oldEnv := os.Environ()
+	os.Clearenv()
+
+	for key, value := range env {
+		require.NoError(t, os.Setenv(key, value))
+	}
+	return func() {
+		os.Clearenv()
+		for key, oldVal := range ToMap(oldEnv) {
+			require.NoError(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
+}