From 569645a050dec9db212b9e49bde6ed2537012407 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mislav=20Marohni=C4=87?= <mislav.marohnic@gmail.com>
Date: Wed, 1 Jul 2020 14:34:44 +0200
Subject: [PATCH] Support `hosts.yml` existing while `config.yml` does not

After a person copies `hosts.yml` to a headless system, they will still
be forced to go through re-authentication flow unless they copy or
initialize a `config.yml` as well. This fixes respecting authentication
info from `hosts.yml` even if `config.yml` is missing.
---
 internal/config/config_file.go      |  6 ++++-
 internal/config/config_file_test.go | 36 +++++++++++++++++++++++------
 internal/config/config_type.go      |  8 +++++--
 internal/config/testing.go          |  6 ++++-
 4 files changed, 45 insertions(+), 11 deletions(-)

diff --git a/internal/config/config_file.go b/internal/config/config_file.go
index 49a2770d3..af2c2d560 100644
--- a/internal/config/config_file.go
+++ b/internal/config/config_file.go
@@ -138,7 +138,11 @@ func migrateConfig(filename string) error {
 func ParseConfig(filename string) (Config, error) {
 	_, root, err := parseConfigFile(filename)
 	if err != nil {
-		return nil, err
+		if os.IsNotExist(err) {
+			root = NewBlankRoot()
+		} else {
+			return nil, err
+		}
 	}
 
 	if isLegacy(root) {
diff --git a/internal/config/config_file_test.go b/internal/config/config_file_test.go
index d19130bb5..f921d2c67 100644
--- a/internal/config/config_file_test.go
+++ b/internal/config/config_file_test.go
@@ -110,14 +110,36 @@ github.com:
 }
 
 func Test_parseConfigFile(t *testing.T) {
-	fileContents := []string{"", " ", "\n"}
-	for _, contents := range fileContents {
-		t.Run(fmt.Sprintf("contents: %q", contents), func(t *testing.T) {
-			defer StubConfig(contents, "")()
+	tests := []struct {
+		contents string
+		wantsErr bool
+	}{
+		{
+			contents: "",
+			wantsErr: true,
+		},
+		{
+			contents: " ",
+			wantsErr: false,
+		},
+		{
+			contents: "\n",
+			wantsErr: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(fmt.Sprintf("contents: %q", tt.contents), func(t *testing.T) {
+			defer StubConfig(tt.contents, "")()
 			_, yamlRoot, err := parseConfigFile("config.yml")
-			eq(t, err, nil)
-			eq(t, yamlRoot.Content[0].Kind, yaml.MappingNode)
-			eq(t, len(yamlRoot.Content[0].Content), 0)
+			if tt.wantsErr != (err != nil) {
+				t.Fatalf("got error: %v", err)
+			}
+			if tt.wantsErr {
+				return
+			}
+			assert.Equal(t, yaml.MappingNode, yamlRoot.Content[0].Kind)
+			assert.Equal(t, 0, len(yamlRoot.Content[0].Content))
 		})
 	}
 }
diff --git a/internal/config/config_type.go b/internal/config/config_type.go
index a57d21dec..85e5c0d4a 100644
--- a/internal/config/config_type.go
+++ b/internal/config/config_type.go
@@ -123,7 +123,11 @@ func NewConfig(root *yaml.Node) Config {
 }
 
 func NewBlankConfig() Config {
-	return NewConfig(&yaml.Node{
+	return NewConfig(NewBlankRoot())
+}
+
+func NewBlankRoot() *yaml.Node {
+	return &yaml.Node{
 		Kind: yaml.DocumentNode,
 		Content: []*yaml.Node{
 			{
@@ -168,7 +172,7 @@ func NewBlankConfig() Config {
 				},
 			},
 		},
-	})
+	}
 }
 
 // This type implements a Config interface and represents a config file on disk.
diff --git a/internal/config/testing.go b/internal/config/testing.go
index 59c2ff212..a49178705 100644
--- a/internal/config/testing.go
+++ b/internal/config/testing.go
@@ -42,7 +42,11 @@ func StubConfig(main, hosts string) func() {
 	ReadConfigFile = func(fn string) ([]byte, error) {
 		switch path.Base(fn) {
 		case "config.yml":
-			return []byte(main), nil
+			if main == "" {
+				return []byte(nil), os.ErrNotExist
+			} else {
+				return []byte(main), nil
+			}
 		case "hosts.yml":
 			if hosts == "" {
 				return []byte(nil), os.ErrNotExist