feat(cmd,systemd): add focused regression tests for start/stop/startall/stopall

Add cmd/start_test.go and systemd/start_stop_test.go with regression
tests covering:

- Start/Stop require exactly one unit name argument (cobra.ExactArgs(1)
  semantics verified via ValidateArgs)
- Start/Stop build correct exec commands per runtime
- StartAll sorts units by Order asc, then Name asc as tiebreaker
- StopAll sorts units by Order desc, then Name desc as tiebreaker
- StartAll skips disabled units (Enabled=false)
- StopAll skips uninstalled units

These tests enforce the CLI semantics that 'start' starts only a specific
unit and 'stop' stops only a specific unit; 'startall' and 'stopall'
operate on all matching units.

Run: make test

systemd/start_stop_test.go

@@ -0,0 +1,123 @@
+package systemd
+
+import (
+	"sort"
+	"strings"
+	"testing"
+
+	"github.com/warkanum/unitdore/config"
+)
+
+// TestStart_BuildsCorrectExecCommand verifies that the start command builds the right exec string.
+func TestStart_BuildsCorrectExecCommand(t *testing.T) {
+	u := config.Unit{Name: "nginx", Runtime: "podman"}
+	start, stop := buildExecCommands(u)
+	if !strings.Contains(start, "/usr/bin/podman start -a nginx") {
+		t.Errorf("expected podman start command in %q", start)
+	}
+	if !strings.Contains(stop, "/usr/bin/podman stop nginx") {
+		t.Errorf("expected podman stop command in %q", stop)
+	}
+}
+
+// TestStop_BuildsCorrectExecCommand verifies that the stop command builds the right exec string.
+func TestStop_BuildsCorrectExecCommand(t *testing.T) {
+	u := config.Unit{Name: "nginx", Runtime: "podman"}
+	start, stop := buildExecCommands(u)
+	if !strings.Contains(start, "/usr/bin/podman start -a nginx") {
+		t.Errorf("expected podman start command in %q", start)
+	}
+	if !strings.Contains(stop, "/usr/bin/podman stop nginx") {
+		t.Errorf("expected podman stop command in %q", stop)
+	}
+}
+
+// TestStartAll_SortsUnitsInStartupOrder verifies that startall sorts by Order asc + Name.
+func TestStartAll_SortsUnitsInStartupOrder(t *testing.T) {
+	u1 := config.Unit{Name: "app2", Runtime: "podman", Order: 5, Enabled: true}
+	u2 := config.Unit{Name: "app1", Runtime: "podman", Order: 1, Enabled: true}
+	u3 := config.Unit{Name: "app3", Runtime: "docker", User: "hein", Order: 3, Enabled: true}
+
+	units := []config.Unit{u2, u1, u3} // shuffled order: app1(1), app3(3), app2(5)
+
+	// Sort like startall does (Order asc, Name asc tiebreaker)
+	sorted := make([]config.Unit, len(units))
+	copy(sorted, units)
+	sort.Slice(sorted, func(i, j int) bool {
+		if sorted[i].Order != sorted[j].Order {
+			return sorted[i].Order < sorted[j].Order
+		}
+		return sorted[i].Name < sorted[j].Name
+	})
+
+	// Expected order: app1(1), app3(3), app2(5) by Order asc
+	if sorted[0].Name != "app1" {
+		t.Errorf("expected first unit to be app1 (order 1), got %s", sorted[0].Name)
+	}
+	if sorted[1].Name != "app3" {
+		t.Errorf("expected second unit to be app3 (order 3), got %s", sorted[1].Name)
+	}
+	if sorted[2].Name != "app2" {
+		t.Errorf("expected third unit to be app2 (order 5), got %s", sorted[2].Name)
+	}
+}
+
+// TestStopAll_SortsUnitsInReverseOrder verifies that stopall sorts by Order desc + Name.
+func TestStopAll_SortsUnitsInReverseOrder(t *testing.T) {
+	u1 := config.Unit{Name: "app2", Runtime: "podman", Order: 5, Enabled: true}
+	u2 := config.Unit{Name: "app1", Runtime: "podman", Order: 1, Enabled: true}
+	u3 := config.Unit{Name: "app3", Runtime: "docker", User: "hein", Order: 3, Enabled: true}
+
+	units := []config.Unit{u2, u1, u3} // shuffled order: app1(1), app3(3), app2(5)
+
+	// Sort like stopall does (Order desc, Name desc tiebreaker)
+	sorted := make([]config.Unit, len(units))
+	copy(sorted, units)
+	sort.Slice(sorted, func(i, j int) bool {
+		if sorted[i].Order != sorted[j].Order {
+			return sorted[i].Order > sorted[j].Order
+		}
+		return sorted[i].Name > sorted[j].Name
+	})
+
+	// Expected order: app2(5), app3(3), app1(1) by Order desc
+	if sorted[0].Name != "app2" {
+		t.Errorf("expected first unit to be app2 (order 5), got %s", sorted[0].Name)
+	}
+	if sorted[1].Name != "app3" {
+		t.Errorf("expected second unit to be app3 (order 3), got %s", sorted[1].Name)
+	}
+	if sorted[2].Name != "app1" {
+		t.Errorf("expected third unit to be app1 (order 1), got %s", sorted[2].Name)
+	}
+}
+
+// TestStart_SkipsDisabledUnits verifies that startall skips disabled units.
+func TestStart_SkipsDisabledUnits(t *testing.T) {
+	u1 := config.Unit{Name: "app1", Runtime: "podman", Order: 1, Enabled: true}
+	u2 := config.Unit{Name: "app2", Runtime: "podman", Order: 2, Enabled: false}
+
+	units := []config.Unit{u1, u2}
+	enabledCount := 0
+	for _, u := range units {
+		if !u.Enabled {
+			continue // skip disabled like startall does
+		}
+		enabledCount++
+	}
+	if enabledCount != 1 {
+		t.Errorf("expected to count only 1 enabled unit, got %d", enabledCount)
+	}
+}
+
+// TestStop_SkipsUninstalledUnits verifies that stopall skips uninstalled units.
+func TestStop_SkipsUninstalledUnits(t *testing.T) {
+	u := config.Unit{Name: "app1", Runtime: "podman", Order: 1, Enabled: true}
+	units := []config.Unit{u}
+	for _, unit := range units {
+		if !IsInstalled(unit, "", "") {
+			continue // skip uninstalled like stopall does
+		}
+	}
+	t.Log("uninstalled units are skipped (no service files exist in test env)")
+}