agent: small refactoring and tests for battery package (#1872)

agent/battery/battery_linux_test.go

@@ -0,0 +1,201 @@
+//go:build testing && linux
+
+package battery
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+// setupFakeSysfs creates a temporary sysfs-like tree under t.TempDir(),
+// swaps sysfsPowerSupply, resets the sync.Once caches, and restores
+// everything on cleanup. Returns a helper to create battery directories.
+func setupFakeSysfs(t *testing.T) (tmpDir string, addBattery func(name, capacity, status string)) {
+	t.Helper()
+
+	tmp := t.TempDir()
+	resetBatteryState(tmp)
+
+	write := func(path, content string) {
+		t.Helper()
+		dir := filepath.Dir(path)
+		if err := os.MkdirAll(dir, 0o755); err != nil {
+			t.Fatal(err)
+		}
+		if err := os.WriteFile(path, []byte(content), 0o644); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	addBattery = func(name, capacity, status string) {
+		t.Helper()
+		batDir := filepath.Join(tmp, name)
+		write(filepath.Join(batDir, "type"), "Battery")
+		write(filepath.Join(batDir, "capacity"), capacity)
+		write(filepath.Join(batDir, "status"), status)
+	}
+
+	return tmp, addBattery
+}
+
+func TestParseSysfsState(t *testing.T) {
+	tests := []struct {
+		input string
+		want  uint8
+	}{
+		{"Empty", stateEmpty},
+		{"Full", stateFull},
+		{"Charging", stateCharging},
+		{"Discharging", stateDischarging},
+		{"Not charging", stateIdle},
+		{"", stateUnknown},
+		{"SomethingElse", stateUnknown},
+	}
+	for _, tt := range tests {
+		assert.Equal(t, tt.want, parseSysfsState(tt.input), "parseSysfsState(%q)", tt.input)
+	}
+}
+
+func TestGetBatteryStats_SingleBattery(t *testing.T) {
+	_, addBattery := setupFakeSysfs(t)
+	addBattery("BAT0", "72", "Discharging")
+
+	pct, state, err := GetBatteryStats()
+	assert.NoError(t, err)
+	assert.Equal(t, uint8(72), pct)
+	assert.Equal(t, stateDischarging, state)
+}
+
+func TestGetBatteryStats_MultipleBatteries(t *testing.T) {
+	_, addBattery := setupFakeSysfs(t)
+	addBattery("BAT0", "80", "Charging")
+	addBattery("BAT1", "40", "Charging")
+
+	pct, state, err := GetBatteryStats()
+	assert.NoError(t, err)
+	// average of 80 and 40 = 60
+	assert.EqualValues(t, 60, pct)
+	assert.Equal(t, stateCharging, state)
+}
+
+func TestGetBatteryStats_FullBattery(t *testing.T) {
+	_, addBattery := setupFakeSysfs(t)
+	addBattery("BAT0", "100", "Full")
+
+	pct, state, err := GetBatteryStats()
+	assert.NoError(t, err)
+	assert.Equal(t, uint8(100), pct)
+	assert.Equal(t, stateFull, state)
+}
+
+func TestGetBatteryStats_EmptyBattery(t *testing.T) {
+	_, addBattery := setupFakeSysfs(t)
+	addBattery("BAT0", "0", "Empty")
+
+	pct, state, err := GetBatteryStats()
+	assert.NoError(t, err)
+	assert.Equal(t, uint8(0), pct)
+	assert.Equal(t, stateEmpty, state)
+}
+
+func TestGetBatteryStats_NotCharging(t *testing.T) {
+	_, addBattery := setupFakeSysfs(t)
+	addBattery("BAT0", "80", "Not charging")
+
+	pct, state, err := GetBatteryStats()
+	assert.NoError(t, err)
+	assert.Equal(t, uint8(80), pct)
+	assert.Equal(t, stateIdle, state)
+}
+
+func TestGetBatteryStats_NoBatteries(t *testing.T) {
+	setupFakeSysfs(t) // empty directory, no batteries
+
+	_, _, err := GetBatteryStats()
+	assert.Error(t, err)
+}
+
+func TestGetBatteryStats_NonBatterySupplyIgnored(t *testing.T) {
+	tmp, addBattery := setupFakeSysfs(t)
+
+	// Add a real battery
+	addBattery("BAT0", "55", "Charging")
+
+	// Add an AC adapter (type != Battery) - should be ignored
+	acDir := filepath.Join(tmp, "AC0")
+	if err := os.MkdirAll(acDir, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(acDir, "type"), []byte("Mains"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	pct, state, err := GetBatteryStats()
+	assert.NoError(t, err)
+	assert.Equal(t, uint8(55), pct)
+	assert.Equal(t, stateCharging, state)
+}
+
+func TestGetBatteryStats_InvalidCapacitySkipped(t *testing.T) {
+	tmp, addBattery := setupFakeSysfs(t)
+
+	// One battery with valid capacity
+	addBattery("BAT0", "90", "Discharging")
+
+	// Another with invalid capacity text
+	badDir := filepath.Join(tmp, "BAT1")
+	if err := os.MkdirAll(badDir, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(badDir, "type"), []byte("Battery"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(badDir, "capacity"), []byte("not-a-number"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(badDir, "status"), []byte("Discharging"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	pct, _, err := GetBatteryStats()
+	assert.NoError(t, err)
+	// Only BAT0 counted
+	assert.Equal(t, uint8(90), pct)
+}
+
+func TestGetBatteryStats_UnknownStatusOnly(t *testing.T) {
+	_, addBattery := setupFakeSysfs(t)
+	addBattery("BAT0", "50", "SomethingWeird")
+
+	_, _, err := GetBatteryStats()
+	assert.Error(t, err)
+}
+
+func TestHasReadableBattery_True(t *testing.T) {
+	_, addBattery := setupFakeSysfs(t)
+	addBattery("BAT0", "50", "Charging")
+
+	assert.True(t, HasReadableBattery())
+}
+
+func TestHasReadableBattery_False(t *testing.T) {
+	setupFakeSysfs(t) // no batteries
+
+	assert.False(t, HasReadableBattery())
+}
+
+func TestHasReadableBattery_NoCapacityFile(t *testing.T) {
+	tmp, _ := setupFakeSysfs(t)
+
+	// Battery dir with type file but no capacity file
+	batDir := filepath.Join(tmp, "BAT0")
+	err := os.MkdirAll(batDir, 0o755)
+	assert.NoError(t, err)
+	err = os.WriteFile(filepath.Join(batDir, "type"), []byte("Battery"), 0o644)
+	assert.NoError(t, err)
+
+	assert.False(t, HasReadableBattery())
+}