Truncate the file to avoid messing up the config file

ecs-cli/modules/config/readwriter.go

@@ -126,6 +126,11 @@ func (rdwr *IniReadWriter) Save(dest *Destination) error {
 	// Open the file, optionally creating it with our desired permissions.
 	// This will let us pass it (as io.Writer) to go-ini but let us control the file.
 	configFile, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE, configFileMode)
+
+	// Truncate the file in case the earlier contents are longer than the new
+	// contents, so there will not be any trash at the end of the file
+	configFile.Truncate(0)
+
 	if err != nil {
 		logrus.Errorf("Unable to open/create %s with mode %s", path, configFileMode)
 		return err

ecs-cli/modules/config/readwriter_test.go

@@ -17,9 +17,14 @@ import (
 	"io/ioutil"
 	"os"
 	"testing"
+
+	"github.com/stretchr/testify/assert"
 )
 
-const testClusterName = "test-cluster"
+const (
+	testClusterName = "test-cluster"
+	testAWSProfile  = "aws-profile"
+)
 
 func newMockDestination() (*Destination, error) {
 	tmpPath, err := ioutil.TempDir(os.TempDir(), "ecs-cli-test-")
@@ -37,120 +42,97 @@ func newMockDestination() (*Destination, error) {
 
 func setupParser(t *testing.T, dest *Destination, shouldBeInitialized bool) *IniReadWriter {
 	iniCfg, err := newIniConfig(dest)
-	if err != nil {
-		t.Fatal("Error creating config ini", err)
-	}
+	assert.NoError(t, err, "Error creating config ini")
+
 	parser := &IniReadWriter{Destination: dest, cfg: iniCfg}
 
 	// Test when unitialized.
 	initialized, err := parser.IsInitialized()
-	if err != nil {
-		t.Errorf("Error getting if initialized from ini", err)
-	}
-
-	if shouldBeInitialized != initialized {
-		t.Error("Unexpected state during parser initialization. Expected initialized to be [%s] but found [%s]", shouldBeInitialized, initialized)
-	}
+	assert.NoError(t, err, "Error getting if initialized from ini")
+	assert.Equal(t, shouldBeInitialized, initialized, "Unexpected state during parser initialization.")
 
 	return parser
 }
 
-func createConfig(t *testing.T, parser *IniReadWriter, dest *Destination) {
+func saveConfigWithCluster(t *testing.T, parser *IniReadWriter, dest *Destination) {
+	saveConfig(t, parser, dest, &SectionKeys{Cluster: testClusterName})
+}
+
+func saveConfig(t *testing.T, parser *IniReadWriter, dest *Destination, sectionKeys *SectionKeys) {
 	// Create a new config file
-	newConfig := &CliConfig{&SectionKeys{Cluster: testClusterName}}
+	newConfig := &CliConfig{sectionKeys}
 	err := parser.ReadFrom(newConfig)
-	if err != nil {
-		t.Fatalf("Could not create config from struct", err)
-	}
+	assert.NoError(t, err, "Could not create config from struct")
 
 	err = parser.Save(dest)
-	if err != nil {
-		t.Fatalf("Could not save config file", err)
-	}
+	assert.NoError(t, err, "Could not save config file")
 }
 
 func TestConfigPermissions(t *testing.T) {
 	dest, err := newMockDestination()
-	if err != nil {
-		t.Fatal("Error creating mock config destination:", err)
-	}
+	assert.NoError(t, err, "Error creating mock config destination")
+
 	parser := setupParser(t, dest, false)
 
 	err = os.MkdirAll(dest.Path, *dest.Mode)
-	if err != nil {
-		t.Fatalf("Could not create config directory: ", err)
-	}
+	assert.NoError(t, err, "Could not create config directory")
+
 	defer os.RemoveAll(dest.Path)
 
 	// Create config file and confirm it has expected initial permissions
-	createConfig(t, parser, dest)
+	saveConfigWithCluster(t, parser, dest)
 
 	path := configPath(dest)
 	confirmConfigMode(t, path, configFileMode)
 
 	// Now set the config mode to something bad
 	badMode := os.FileMode(0777)
 	err = os.Chmod(path, badMode)
-	if err != nil {
-		t.Fatalf("Unable to change mode of new config %v", path)
-	}
+	assert.NoError(t, err, "Unable to change mode of new config %v", path)
+
 	confirmConfigMode(t, path, badMode)
 
 	// Save the config and confirm it's fixed again
 	err = parser.Save(dest)
-	if err != nil {
-		t.Fatalf("Unable to save to new config %v", path)
-	}
+	assert.NoError(t, err, "Unable to save to new config %v", path)
+
 	confirmConfigMode(t, path, configFileMode)
 }
 
 func confirmConfigMode(t *testing.T, path string, expected os.FileMode) {
 	info, err := os.Stat(path)
-	if err != nil {
-		t.Fatalf("Unable to stat config file %s", path)
-	}
+	assert.NoError(t, err, "Unable to stat config file %s", path)
 
 	mode := info.Mode()
-	if mode != expected {
-		t.Fatalf("Mode of config %v not expected %v", mode, expected)
-	}
+	assert.Equal(t, expected, mode, "Made of config does not match")
+
 }
 
 func TestNewConfigReadWriter(t *testing.T) {
 	dest, err := newMockDestination()
-	if err != nil {
-		t.Fatal("Error creating mock config destination:", err)
-	}
+	assert.NoError(t, err, "Error creating mock config destination")
+
 	parser := setupParser(t, dest, false)
 
 	err = os.MkdirAll(dest.Path, *dest.Mode)
-	if err != nil {
-		t.Fatalf("Could not create config directory: ", err)
-	}
+	assert.NoError(t, err, "Could not create config directory")
+
 	defer os.RemoveAll(dest.Path)
 
-	createConfig(t, parser, dest)
+	saveConfigWithCluster(t, parser, dest)
 
 	// Reinitialize from the written file.
 	parser = setupParser(t, dest, true)
 
 	readConfig, err := parser.GetConfig()
-	if err != nil {
-		t.Errorf("Error reading config:", err)
-	}
-
-	if testClusterName != readConfig.Cluster {
-		t.Errorf("Cluster name mismatch in config. Expected [%s] Got [%s]", testClusterName, readConfig.Cluster)
-	}
-	if !parser.IsKeyPresent(ecsSectionKey, composeProjectNamePrefixKey) || readConfig.ComposeProjectNamePrefix != "" {
-		t.Errorf("Compose Project prefix name mismatch in config. Expected empty string Got [%s]", readConfig.ComposeProjectNamePrefix)
-	}
-	if !parser.IsKeyPresent(ecsSectionKey, composeServiceNamePrefixKey) || readConfig.ComposeServiceNamePrefix != "" {
-		t.Errorf("Compose service name prefix mismatch in config. Expected empty string Got [%s]", readConfig.ComposeServiceNamePrefix)
-	}
-	if !parser.IsKeyPresent(ecsSectionKey, cfnStackNamePrefixKey) || readConfig.CFNStackNamePrefix != "" {
-		t.Errorf("CFNStackNamePrefix mismatch in config. Expected empty string Got [%s]", readConfig.CFNStackNamePrefix)
-	}
+	assert.NoError(t, err, "Error reading config")
+	assert.Equal(t, testClusterName, readConfig.Cluster, "Cluster name mismatch in config.")
+	assert.True(t, parser.IsKeyPresent(ecsSectionKey, composeProjectNamePrefixKey), "Compose project prefix name should exist in config.")
+	assert.Empty(t, readConfig.ComposeProjectNamePrefix, "Compose project prefix name should be empty.")
+	assert.True(t, parser.IsKeyPresent(ecsSectionKey, composeServiceNamePrefixKey), "Compose service name prefix should exist in config.")
+	assert.Empty(t, readConfig.ComposeServiceNamePrefix, "Compose service prefix name should be empty.")
+	assert.True(t, parser.IsKeyPresent(ecsSectionKey, cfnStackNamePrefixKey), "CFNStackNamePrefix should exist in config.")
+	assert.Empty(t, readConfig.CFNStackNamePrefix, "CFNStackNamePrefix should be empty.")
 }
 
 func TestMissingPrefixes(t *testing.T) {
@@ -162,33 +144,52 @@ aws_access_key_id =
 aws_secret_access_key =
 `
 	dest, err := newMockDestination()
-	if err != nil {
-		t.Fatal("Error creating mock config destination:", err)
-	}
+	assert.NoError(t, err, "Error creating mock config destination")
+
 	err = os.MkdirAll(dest.Path, *dest.Mode)
-	if err != nil {
-		t.Fatalf("Could not create config directory: ", err)
-	}
+	assert.NoError(t, err, "Could not create config directory")
+
 	defer os.RemoveAll(dest.Path)
 
-	if err = ioutil.WriteFile(dest.Path+"/"+configFileName, []byte(configContentsNoPrefixes), *dest.Mode); err != nil {
-		t.Fatal(err)
-	}
+	err = ioutil.WriteFile(dest.Path+"/"+configFileName, []byte(configContentsNoPrefixes), *dest.Mode)
+	assert.NoError(t, err)
 
 	parser := setupParser(t, dest, true)
-	readConfig, err := parser.GetConfig()
-	if err != nil {
-		t.Errorf("Error reading config:", err)
-	}
+	_, err = parser.GetConfig()
+	assert.NoError(t, err, "Error reading config")
+	assert.False(t, parser.IsKeyPresent(ecsSectionKey, cfnStackNamePrefixKey), "CFNStackNamePrefix should not exist in config")
+	assert.False(t, parser.IsKeyPresent(ecsSectionKey, composeServiceNamePrefixKey), "Compose service name prefix should not exist in config")
+	assert.False(t, parser.IsKeyPresent(ecsSectionKey, composeProjectNamePrefixKey), "Compose project name prefix should not exist in config")
+}
 
-	if parser.IsKeyPresent(ecsSectionKey, cfnStackNamePrefixKey) {
-		t.Errorf("Expected key [%s] not to be present. Got value=[%s]", cfnStackNamePrefixKey, readConfig.CFNStackNamePrefix)
-	}
-	if parser.IsKeyPresent(ecsSectionKey, composeServiceNamePrefixKey) {
-		t.Errorf("Expected key [%s] not to be present. Got value=[%s]", composeServiceNamePrefixKey, readConfig.ComposeServiceNamePrefix)
-	}
-	if parser.IsKeyPresent(ecsSectionKey, composeProjectNamePrefixKey) {
-		t.Errorf("Expected key [%s] not to be present. Got value=[%s]", composeProjectNamePrefixKey, readConfig.ComposeProjectNamePrefix)
-	}
+func TestConfigFileTruncation(t *testing.T) {
+	configContents := `[ecs]
+cluster = very-long-cluster-name
+aws_profile = some-long-profile
+region = us-west-2
+aws_access_key_id =
+aws_secret_access_key =
+compose-project-name-prefix = ecscompose-
+compose-service-name-prefix = ecscompose-service-
+cfn-stack-name-prefix = amazon-ecs-cli-setup-
+`
+	dest, err := newMockDestination()
+	assert.NoError(t, err, "Error creating mock config destination")
+
+	parser := setupParser(t, dest, false)
+
+	err = os.MkdirAll(dest.Path, *dest.Mode)
+	assert.NoError(t, err, "Could not create config directory")
+
+	defer os.RemoveAll(dest.Path)
+
+	// Save config for the first time
+	err = ioutil.WriteFile(dest.Path+"/"+configFileName, []byte(configContents), *dest.Mode)
+	assert.NoError(t, err)
+
+	// Save config with shorter cluster name
+	saveConfigWithCluster(t, parser, dest)
 
+	_, err = newIniConfig(dest)
+	assert.NoError(t, err)
 }