A few extra fixes and tests.

config_test.go

@@ -0,0 +1,54 @@
+package kong_test
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"os"
+	"testing"
+
+	"github.com/alecthomas/kong"
+	"github.com/stretchr/testify/require"
+)
+
+func TestMultipleConfigLoading(t *testing.T) {
+	var cli struct {
+		Flag string `json:"flag,omitempty"`
+	}
+
+	cli.Flag = "first"
+	first, cleanFirst := makeConfig(t, &cli)
+	defer cleanFirst()
+
+	cli.Flag = ""
+	second, cleanSecond := makeConfig(t, &cli)
+	defer cleanSecond()
+
+	p := mustNew(t, &cli, kong.Configuration(kong.JSON, first, second))
+	_, err := p.Parse(nil)
+	require.NoError(t, err)
+	require.Equal(t, "first", cli.Flag)
+}
+
+func TestConfigValidation(t *testing.T) {
+	var cli struct {
+		Flag string `json:"flag,omitempty" enum:"valid"`
+	}
+
+	cli.Flag = "invalid"
+	conf, cleanConf := makeConfig(t, &cli)
+	defer cleanConf()
+
+	p := mustNew(t, &cli, kong.Configuration(kong.JSON, conf))
+	_, err := p.Parse(nil)
+	require.Error(t, err)
+}
+
+func makeConfig(t *testing.T, config interface{}) (path string, cleanup func()) {
+	t.Helper()
+	w, err := ioutil.TempFile("", "")
+	require.NoError(t, err)
+	defer w.Close()
+	err = json.NewEncoder(w).Encode(config)
+	require.NoError(t, err)
+	return w.Name(), func() { os.Remove(w.Name()) }
+}

kong.go

@@ -326,7 +326,6 @@ func (k *Kong) FatalIfErrorf(err error, args ...interface{}) {
 	if err, ok := err.(*ParseError); ok && k.usageOnError {
 		fmt.Fprintln(k.Stdout)
 		options := k.helpOptions
-		options.Summary = true
 		_ = k.help(options, err.Context)
 	}
 	k.Exit(1)

kong_test.go

@@ -707,3 +707,12 @@ func TestDefaultValueIsHyphen(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, "-", cli.Flag)
 }
+
+func TestDefaultEnumValidated(t *testing.T) {
+	var cli struct {
+		Flag string `default:"invalid" enum:"valid"`
+	}
+	p := mustNew(t, &cli)
+	_, err := p.Parse(nil)
+	require.Error(t, err)
+}

options_test.go

@@ -1,9 +1,6 @@
 package kong
 
 import (
-	"encoding/json"
-	"io/ioutil"
-	"os"
 	"reflect"
 	"testing"
 
@@ -21,35 +18,6 @@ func TestOptions(t *testing.T) {
 	require.Nil(t, p.Exit)
 }
 
-func TestConfigLoading(t *testing.T) {
-	first, err := ioutil.TempFile("", "")
-	require.NoError(t, err)
-	defer first.Close()
-	defer os.Remove(first.Name())
-	second, err := ioutil.TempFile("", "")
-	require.NoError(t, err)
-	defer second.Close()
-	defer os.Remove(second.Name())
-
-	var cli struct {
-		Flag string `json:"flag,omitempty"`
-	}
-
-	cli.Flag = "first"
-	err = json.NewEncoder(first).Encode(&cli)
-	require.NoError(t, err)
-
-	cli.Flag = ""
-	err = json.NewEncoder(second).Encode(&cli)
-	require.NoError(t, err)
-
-	p, err := New(&cli, Configuration(JSON, first.Name(), second.Name()))
-	require.NoError(t, err)
-	_, err = p.Parse(nil)
-	require.NoError(t, err)
-	require.Equal(t, "first", cli.Flag)
-}
-
 type impl string
 
 func (impl) Method() {}

resolver_test.go

@@ -74,6 +74,24 @@ func TestEnvarsTag(t *testing.T) {
 	require.Equal(t, []int{5, 2, 9}, cli.Slice)
 }
 
+func TestEnvarsWithDefault(t *testing.T) {
+	var cli struct {
+		Flag string `env:"KONG_FLAG" default:"default"`
+	}
+	parser, restoreEnv := newEnvParser(t, &cli, envMap{})
+	defer restoreEnv()
+
+	_, err := parser.Parse(nil)
+	require.NoError(t, err)
+	require.Equal(t, "default", cli.Flag)
+
+	parser, restoreEnv = newEnvParser(t, &cli, envMap{"KONG_FLAG": "moo"})
+	defer restoreEnv()
+	_, err = parser.Parse(nil)
+	require.NoError(t, err)
+	require.Equal(t, "moo", cli.Flag)
+}
+
 func TestJSONBasic(t *testing.T) {
 	var cli struct {
 		String          string