feat(pacman): implement Manager interface for pacman package manager

Adds full pacman wrapper with:
- All Manager interface methods (Install, Remove, Purge, Upgrade, Update,
  List, Search, Info, IsInstalled, Version, Available)
- Linux implementation using exec.CommandContext
- Non-linux stubs returning ErrUnsupportedPlatform
- Output parsing for -Q, -Ss, -Si formats
- Options support: WithSudo, WithAssumeYes, WithDryRun, WithRoot
- Unit tests for parsing and argument building

pacman/pacman_test.go

@@ -0,0 +1,140 @@
+package pacman
+
+import (
+	"testing"
+
+	"github.com/gogrlx/snack"
+)
+
+func TestParseList(t *testing.T) {
+	input := `linux 6.7.4.arch1-1
+glibc 2.39-1
+bash 5.2.026-2
+`
+	pkgs := parseList(input)
+	if len(pkgs) != 3 {
+		t.Fatalf("expected 3 packages, got %d", len(pkgs))
+	}
+	if pkgs[0].Name != "linux" || pkgs[0].Version != "6.7.4.arch1-1" {
+		t.Errorf("unexpected first package: %+v", pkgs[0])
+	}
+	if !pkgs[0].Installed {
+		t.Error("expected Installed=true")
+	}
+}
+
+func TestParseSearch(t *testing.T) {
+	input := `core/linux 6.7.4.arch1-1 [installed]
+    The Linux kernel and modules
+extra/linux-lts 6.6.14-1
+    The LTS Linux kernel and modules
+`
+	pkgs := parseSearch(input)
+	if len(pkgs) != 2 {
+		t.Fatalf("expected 2 packages, got %d", len(pkgs))
+	}
+	if pkgs[0].Repository != "core" || pkgs[0].Name != "linux" {
+		t.Errorf("unexpected first package: %+v", pkgs[0])
+	}
+	if !pkgs[0].Installed {
+		t.Error("expected first package to be installed")
+	}
+	if pkgs[1].Installed {
+		t.Error("expected second package to not be installed")
+	}
+	if pkgs[1].Description != "The LTS Linux kernel and modules" {
+		t.Errorf("unexpected description: %q", pkgs[1].Description)
+	}
+}
+
+func TestParseInfo(t *testing.T) {
+	input := `Repository      : core
+Name            : linux
+Version         : 6.7.4.arch1-1
+Description     : The Linux kernel and modules
+Architecture    : x86_64
+`
+	pkg := parseInfo(input)
+	if pkg == nil {
+		t.Fatal("expected non-nil package")
+	}
+	if pkg.Name != "linux" {
+		t.Errorf("expected name 'linux', got %q", pkg.Name)
+	}
+	if pkg.Version != "6.7.4.arch1-1" {
+		t.Errorf("unexpected version: %q", pkg.Version)
+	}
+	if pkg.Arch != "x86_64" {
+		t.Errorf("unexpected arch: %q", pkg.Arch)
+	}
+	if pkg.Repository != "core" {
+		t.Errorf("unexpected repo: %q", pkg.Repository)
+	}
+}
+
+func TestBuildArgs(t *testing.T) {
+	tests := []struct {
+		name     string
+		base     []string
+		opts     snack.Options
+		wantCmd  string
+		wantArgs []string
+	}{
+		{
+			name:     "basic",
+			base:     []string{"-S", "vim"},
+			opts:     snack.Options{},
+			wantCmd:  "pacman",
+			wantArgs: []string{"-S", "vim"},
+		},
+		{
+			name:     "with sudo",
+			base:     []string{"-S", "vim"},
+			opts:     snack.Options{Sudo: true},
+			wantCmd:  "sudo",
+			wantArgs: []string{"pacman", "-S", "vim"},
+		},
+		{
+			name:     "with root and noconfirm",
+			base:     []string{"-S", "vim"},
+			opts:     snack.Options{Root: "/mnt", AssumeYes: true},
+			wantCmd:  "pacman",
+			wantArgs: []string{"-r", "/mnt", "-S", "vim", "--noconfirm"},
+		},
+		{
+			name:     "dry run",
+			base:     []string{"-S", "vim"},
+			opts:     snack.Options{DryRun: true},
+			wantCmd:  "pacman",
+			wantArgs: []string{"-S", "vim", "--print"},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			cmd, args := buildArgs(tt.base, tt.opts)
+			if cmd != tt.wantCmd {
+				t.Errorf("cmd = %q, want %q", cmd, tt.wantCmd)
+			}
+			if len(args) != len(tt.wantArgs) {
+				t.Fatalf("args = %v, want %v", args, tt.wantArgs)
+			}
+			for i := range args {
+				if args[i] != tt.wantArgs[i] {
+					t.Errorf("args[%d] = %q, want %q", i, args[i], tt.wantArgs[i])
+				}
+			}
+		})
+	}
+}
+
+func TestInterfaceCompliance(t *testing.T) {
+	var _ snack.Manager = (*Pacman)(nil)
+}
+
+func TestName(t *testing.T) {
+	p := New()
+	if p.Name() != "pacman" {
+		t.Errorf("Name() = %q, want %q", p.Name(), "pacman")
+	}
+}