fix(battery): hide segment when no batteries

resolves #633

src/environment.go

@@ -32,6 +32,12 @@ func (e *commandError) Error() string {
 	return e.err
 }
 
+type noBatteryError struct{}
+
+func (m *noBatteryError) Error() string {
+	return "no battery"
+}
+
 type fileInfo struct {
 	parentFolder string
 	path         string
@@ -253,6 +259,9 @@ func (env *environment) getBatteryInfo() (*battery.Battery, error) {
 	if err != nil {
 		return nil, err
 	}
+	if batteries == nil {
+		return nil, &noBatteryError{}
+	}
 	batt := &battery.Battery{}
 	for _, bt := range batteries {
 		batt.Current += bt.Current

src/segment_battery.go

@@ -35,22 +35,8 @@ const (
 func (b *batt) enabled() bool {
 	var err error
 	b.Battery, err = b.env.getBatteryInfo()
-
-	displayError := b.props.getBool(DisplayError, false)
-	if err != nil && displayError {
-		b.Error = err.Error()
-		return true
-	}
-	if err != nil {
-		// On Windows, it sometimes errors when the battery is full.
-		// This hack ensures we display a fully charged battery, even if
-		// that state can be incorrect. It's better to "ignore" the error
-		// than to not display the segment at all as that will confuse users.
-		b.Battery = &battery.Battery{
-			Current: 100,
-			Full:    100,
-			State:   battery.Full,
-		}
+	if !b.enabledWhileError(err) {
+		return false
 	}
 
 	display := b.props.getBool(DisplayCharging, true)
@@ -83,6 +69,30 @@ func (b *batt) enabled() bool {
 	return true
 }
 
+func (b *batt) enabledWhileError(err error) bool {
+	if err == nil {
+		return true
+	}
+	if _, ok := err.(*noBatteryError); ok {
+		return false
+	}
+	displayError := b.props.getBool(DisplayError, false)
+	if !displayError {
+		return false
+	}
+	b.Error = err.Error()
+	// On Windows, it sometimes errors when the battery is full.
+	// This hack ensures we display a fully charged battery, even if
+	// that state can be incorrect. It's better to "ignore" the error
+	// than to not display the segment at all as that will confuse users.
+	b.Battery = &battery.Battery{
+		Current: 100,
+		Full:    100,
+		State:   battery.Full,
+	}
+	return true
+}
+
 func (b *batt) string() string {
 	segmentTemplate := b.props.getString(SegmentTemplate, "{{.Icon}}{{ if not .Error }}{{.Percentage}}{{ end }}{{.Error}}")
 	template := &textTemplate{

src/segment_battery_test.go

@@ -146,8 +146,22 @@ func TestBatteryErrorHidden(t *testing.T) {
 		},
 		env: env,
 	}
-	assert.True(t, b.enabled())
-	assert.Equal(t, "100", b.string())
+	assert.False(t, b.enabled())
+}
+
+func TestBatteryNoBattery(t *testing.T) {
+	env := &MockedEnvironment{}
+	err := &noBatteryError{}
+	env.On("getBatteryInfo", nil).Return(&battery.Battery{}, err)
+	b := &batt{
+		props: &properties{
+			values: map[Property]interface{}{
+				DisplayError: true,
+			},
+		},
+		env: env,
+	}
+	assert.False(t, b.enabled())
 }
 
 func TestBatteryDischargingAndDisplayChargingDisabled(t *testing.T) {