Add config file tests

Signed-off-by: Christopher Crone <christopher.crone@docker.com>

cli/config/config_test.go

@@ -0,0 +1,103 @@
+/*
+	Copyright (c) 2020 Docker Inc.
+
+	Permission is hereby granted, free of charge, to any person
+	obtaining a copy of this software and associated documentation
+	files (the "Software"), to deal in the Software without
+	restriction, including without limitation the rights to use, copy,
+	modify, merge, publish, distribute, sublicense, and/or sell copies
+	of the Software, and to permit persons to whom the Software is
+	furnished to do so, subject to the following conditions:
+
+	The above copyright notice and this permission notice shall be
+	included in all copies or substantial portions of the Software.
+
+	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+	EXPRESS OR IMPLIED,
+	INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+	IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+	HOLDERS BE LIABLE FOR ANY CLAIM,
+	DAMAGES OR OTHER LIABILITY,
+	WHETHER IN AN ACTION OF CONTRACT,
+	TORT OR OTHERWISE,
+	ARISING FROM, OUT OF OR IN CONNECTION WITH
+	THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*/
+
+package config
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"github.com/stretchr/testify/suite"
+)
+
+var sampleConfig = []byte(`{
+	"otherField": "value",
+	"currentContext": "moby"
+}`)
+
+type ConfigTestSuite struct {
+	suite.Suite
+	configDir string
+}
+
+func (s *ConfigTestSuite) BeforeTest(suite, test string) {
+	d, _ := ioutil.TempDir("", "")
+	s.configDir = d
+}
+
+func (s *ConfigTestSuite) AfterTest(suite, test string) {
+	err := os.RemoveAll(s.configDir)
+	require.NoError(s.T(), err)
+}
+
+func writeSampleConfig(t *testing.T, d string) {
+	err := ioutil.WriteFile(filepath.Join(d, ConfigFileName), sampleConfig, 0644)
+	require.NoError(t, err)
+}
+
+func (s *ConfigTestSuite) TestLoadFile() {
+	writeSampleConfig(s.T(), s.configDir)
+	f, err := LoadFile(s.configDir)
+	require.NoError(s.T(), err)
+	require.Equal(s.T(), "moby", f.CurrentContext)
+}
+
+func (s *ConfigTestSuite) TestOverWriteCurrentContext() {
+	writeSampleConfig(s.T(), s.configDir)
+	f, err := LoadFile(s.configDir)
+	require.NoError(s.T(), err)
+	require.Equal(s.T(), "moby", f.CurrentContext)
+
+	err = WriteCurrentContext(s.configDir, "overwrite")
+	require.NoError(s.T(), err)
+	f, err = LoadFile(s.configDir)
+	require.NoError(s.T(), err)
+	require.Equal(s.T(), "overwrite", f.CurrentContext)
+
+	m := map[string]interface{}{}
+	err = loadFile(filepath.Join(s.configDir, ConfigFileName), &m)
+	require.NoError(s.T(), err)
+	require.Equal(s.T(), "overwrite", m["currentContext"])
+	require.Equal(s.T(), "value", m["otherField"])
+}
+
+// TestWriteDefaultContextToEmptyConfig tests a specific case seen on the CI:
+// panic when setting context to default with empty config file
+func (s *ConfigTestSuite) TestWriteDefaultContextToEmptyConfig() {
+	err := WriteCurrentContext(s.configDir, "default")
+	require.NoError(s.T(), err)
+	d, err := ioutil.ReadFile(filepath.Join(s.configDir, ConfigFileName))
+	require.NoError(s.T(), err)
+	require.Equal(s.T(), string(d), "{}")
+}
+
+func TestConfig(t *testing.T) {
+	suite.Run(t, new(ConfigTestSuite))
+}