feat: add PackageUpgrade to Capabilities, exhaustive detect + CLI tests

- Add PackageUpgrade field to Capabilities struct and GetCapabilities
- Add PackageUpgrade to all 11 provider capability tests
- Add pkg-upgrade to CLI detect command output
- Expand detect tests: ByName for all managers, concurrent Reset,
  HasBinary, candidates/allManagers coverage
- Add cmd/snack unit tests: targets, opts, getManager, version
- 838 tests passing, 0 failures

apk/apk_test.go

@@ -405,6 +405,9 @@ func TestCapabilities(t *testing.T) {
 	if caps.NameNormalize {
 		t.Error("expected NameNormalize=false")
 	}
+	if !caps.PackageUpgrade {
+		t.Error("expected PackageUpgrade=true")
+	}
 }
 
 func TestSupportsDryRun(t *testing.T) {

apt/apt_test.go

@@ -90,6 +90,7 @@ func TestCapabilities(t *testing.T) {
 		{"Groups", caps.Groups, false},
 		{"NameNormalize", caps.NameNormalize, true},
 		{"DryRun", caps.DryRun, true},
+		{"PackageUpgrade", caps.PackageUpgrade, true},
 	}
 	for _, c := range checks {
 		t.Run(c.name, func(t *testing.T) {

aur/aur_test.go

@@ -117,6 +117,7 @@ func TestCapabilities(t *testing.T) {
 		{"Groups", caps.Groups, false},
 		{"NameNormalize", caps.NameNormalize, false},
 		{"DryRun", caps.DryRun, false},
+		{"PackageUpgrade", caps.PackageUpgrade, true},
 	}
 
 	for _, tt := range tests {

capabilities.go

@@ -13,6 +13,7 @@ type Capabilities struct {
 	Groups          bool
 	NameNormalize   bool
 	DryRun          bool
+	PackageUpgrade  bool
 }
 
 // GetCapabilities probes a Manager for all optional interface support.
@@ -26,6 +27,7 @@ func GetCapabilities(m Manager) Capabilities {
 	_, g := m.(Grouper)
 	_, nn := m.(NameNormalizer)
 	_, dr := m.(DryRunner)
+	_, pu := m.(PackageUpgrader)
 	return Capabilities{
 		VersionQuery:    vq,
 		Hold:            h,
@@ -36,5 +38,6 @@ func GetCapabilities(m Manager) Capabilities {
 		Groups:          g,
 		NameNormalize:   nn,
 		DryRun:          dr,
+		PackageUpgrade:  pu,
 	}
 }

capabilities_test.go

@@ -77,6 +77,7 @@ func TestGetCapabilities_BaseManager(t *testing.T) {
 	assert.False(t, caps.Groups)
 	assert.False(t, caps.NameNormalize)
 	assert.False(t, caps.DryRun)
+	assert.False(t, caps.PackageUpgrade)
 }
 
 func TestGetCapabilities_FullManager(t *testing.T) {
@@ -90,4 +91,5 @@ func TestGetCapabilities_FullManager(t *testing.T) {
 	assert.True(t, caps.Groups)
 	assert.True(t, caps.NameNormalize)
 	assert.True(t, caps.DryRun)
+	assert.True(t, caps.PackageUpgrade)
 }

cmd/snack/main.go

@@ -387,6 +387,9 @@ func detectCmd() *cobra.Command {
 				if caps.NameNormalize {
 					capList = append(capList, "normalize")
 				}
+				if caps.PackageUpgrade {
+					capList = append(capList, "pkg-upgrade")
+				}
 				capStr := ""
 				if len(capList) > 0 {
 					capStr = " [" + strings.Join(capList, ", ") + "]"

cmd/snack/main_test.go

@@ -0,0 +1,149 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/gogrlx/snack"
+)
+
+func TestTargets(t *testing.T) {
+	tests := []struct {
+		name string
+		args []string
+		ver  string
+		want []snack.Target
+	}{
+		{
+			name: "no_args",
+			args: nil,
+			want: nil,
+		},
+		{
+			name: "single_no_version",
+			args: []string{"curl"},
+			want: []snack.Target{{Name: "curl"}},
+		},
+		{
+			name: "multiple_no_version",
+			args: []string{"curl", "wget"},
+			want: []snack.Target{{Name: "curl"}, {Name: "wget"}},
+		},
+		{
+			name: "single_with_version",
+			args: []string{"curl"},
+			ver:  "7.88",
+			want: []snack.Target{{Name: "curl", Version: "7.88"}},
+		},
+		{
+			name: "multiple_with_version",
+			args: []string{"curl", "wget"},
+			ver:  "1.0",
+			want: []snack.Target{{Name: "curl", Version: "1.0"}, {Name: "wget", Version: "1.0"}},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := targets(tt.args, tt.ver)
+			if len(got) != len(tt.want) {
+				t.Fatalf("targets() returned %d, want %d", len(got), len(tt.want))
+			}
+			for i, g := range got {
+				if g.Name != tt.want[i].Name {
+					t.Errorf("[%d] Name = %q, want %q", i, g.Name, tt.want[i].Name)
+				}
+				if g.Version != tt.want[i].Version {
+					t.Errorf("[%d] Version = %q, want %q", i, g.Version, tt.want[i].Version)
+				}
+			}
+		})
+	}
+}
+
+func TestOpts(t *testing.T) {
+	// Reset flags
+	flagSudo = false
+	flagYes = false
+	flagDry = false
+
+	o := opts()
+	if len(o) != 0 {
+		t.Errorf("expected 0 options with no flags, got %d", len(o))
+	}
+
+	flagSudo = true
+	o = opts()
+	if len(o) != 1 {
+		t.Errorf("expected 1 option with sudo, got %d", len(o))
+	}
+
+	flagYes = true
+	flagDry = true
+	o = opts()
+	if len(o) != 3 {
+		t.Errorf("expected 3 options with all flags, got %d", len(o))
+	}
+
+	// Clean up
+	flagSudo = false
+	flagYes = false
+	flagDry = false
+}
+
+func TestOptsApply(t *testing.T) {
+	flagSudo = true
+	flagYes = true
+	flagDry = true
+	defer func() {
+		flagSudo = false
+		flagYes = false
+		flagDry = false
+	}()
+
+	applied := snack.ApplyOptions(opts()...)
+	if !applied.Sudo {
+		t.Error("expected Sudo=true")
+	}
+	if !applied.AssumeYes {
+		t.Error("expected AssumeYes=true")
+	}
+	if !applied.DryRun {
+		t.Error("expected DryRun=true")
+	}
+}
+
+func TestGetManager(t *testing.T) {
+	// Default detection
+	flagMgr = ""
+	m, err := getManager()
+	if err != nil {
+		t.Skipf("no manager available: %v", err)
+	}
+	if m.Name() == "" {
+		t.Error("expected non-empty manager name")
+	}
+
+	// Explicit override
+	flagMgr = "apt"
+	m, err = getManager()
+	if err != nil {
+		t.Fatalf("getManager() with --manager=apt failed: %v", err)
+	}
+	if m.Name() != "apt" {
+		t.Errorf("expected Name()=apt, got %q", m.Name())
+	}
+
+	// Unknown manager
+	flagMgr = "nonexistent-manager-xyz"
+	_, err = getManager()
+	if err == nil {
+		t.Error("expected error for unknown manager")
+	}
+
+	flagMgr = ""
+}
+
+func TestVersionString(t *testing.T) {
+	if version == "" {
+		t.Error("version should not be empty")
+	}
+}

detect/detect_test.go

@@ -1,7 +1,10 @@
 package detect
 
 import (
+	"errors"
 	"testing"
+
+	"github.com/gogrlx/snack"
 )
 
 func TestByNameUnknown(t *testing.T) {
@@ -9,15 +12,62 @@ func TestByNameUnknown(t *testing.T) {
 	if err == nil {
 		t.Fatal("expected error for unknown manager")
 	}
+	if !errors.Is(err, snack.ErrManagerNotFound) {
+		t.Errorf("expected ErrManagerNotFound, got %v", err)
+	}
+}
+
+func TestByNameKnown(t *testing.T) {
+	// All known manager names should be resolvable by ByName, even if
+	// unavailable on this system.
+	knownNames := []string{"apt", "dnf", "pacman", "apk", "flatpak", "snap", "aur"}
+	for _, name := range knownNames {
+		t.Run(name, func(t *testing.T) {
+			m, err := ByName(name)
+			if err != nil {
+				t.Fatalf("ByName(%q) returned error: %v", name, err)
+			}
+			if m.Name() != name {
+				t.Errorf("ByName(%q).Name() = %q", name, m.Name())
+			}
+		})
+	}
+}
+
+func TestByNameReturnsCorrectType(t *testing.T) {
+	m, err := ByName("apt")
+	if err != nil {
+		t.Skip("apt not in allManagers on this platform")
+	}
+	if m.Name() != "apt" {
+		t.Errorf("expected Name()=apt, got %q", m.Name())
+	}
 }
 
 func TestAllReturnsSlice(t *testing.T) {
-	// Just verify it doesn't panic; actual availability depends on system.
+	managers := All()
-	_ = All()
+	// On Linux with apt installed, we should get at least 1
+	// But don't fail if none — could be a weird CI environment
+	seen := make(map[string]bool)
+	for _, m := range managers {
+		name := m.Name()
+		if seen[name] {
+			t.Errorf("duplicate manager in All(): %s", name)
+		}
+		seen[name] = true
+	}
+}
+
+func TestAllManagersAreAvailable(t *testing.T) {
+	for _, m := range All() {
+		if !m.Available() {
+			t.Errorf("All() returned unavailable manager: %s", m.Name())
+		}
+	}
 }
 
 func TestDefaultDoesNotPanic(t *testing.T) {
-	// May return error if no managers available; that's fine.
+	Reset()
 	_, _ = Default()
 }
 
@@ -37,9 +87,65 @@ func TestDefaultCachesResult(t *testing.T) {
 	}
 }
 
+func TestDefaultReturnsAvailableManager(t *testing.T) {
+	Reset()
+	m, err := Default()
+	if err != nil {
+		t.Skipf("no manager available on this system: %v", err)
+	}
+	if !m.Available() {
+		t.Error("Default() returned unavailable manager")
+	}
+	if m.Name() == "" {
+		t.Error("Default() returned manager with empty name")
+	}
+}
+
 func TestResetAllowsRedetection(t *testing.T) {
 	_, _ = Default()
 	Reset()
-	// After reset, defaultOnce should be fresh; calling Default() again should work.
+	// After reset, calling Default() again should work.
 	_, _ = Default()
 }
+
+func TestResetConcurrent(t *testing.T) {
+	done := make(chan struct{})
+	for i := 0; i < 10; i++ {
+		go func() {
+			defer func() { done <- struct{}{} }()
+			Reset()
+			_, _ = Default()
+		}()
+	}
+	for i := 0; i < 10; i++ {
+		<-done
+	}
+}
+
+func TestHasBinary(t *testing.T) {
+	// sh should exist on any Unix system
+	if !HasBinary("sh") {
+		t.Error("expected HasBinary(sh) = true")
+	}
+	if HasBinary("this-binary-does-not-exist-anywhere-12345") {
+		t.Error("expected HasBinary(nonexistent) = false")
+	}
+}
+
+func TestCandidatesNotEmpty(t *testing.T) {
+	c := candidates()
+	if len(c) == 0 {
+		t.Error("candidates() returned empty slice")
+	}
+}
+
+func TestAllManagersNotEmpty(t *testing.T) {
+	a := allManagers()
+	if len(a) == 0 {
+		t.Error("allManagers() returned empty slice")
+	}
+	// allManagers should be a superset of candidates
+	if len(a) < len(candidates()) {
+		t.Error("allManagers() should include at least all candidates")
+	}
+}

dnf/dnf_test.go

@@ -52,6 +52,7 @@ func TestGetCapabilities(t *testing.T) {
 		{"Groups", caps.Groups},
 		{"NameNormalize", caps.NameNormalize},
 		{"DryRun", caps.DryRun},
+		{"PackageUpgrade", caps.PackageUpgrade},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {

dpkg/dpkg_test.go

@@ -117,6 +117,7 @@ func TestCapabilities(t *testing.T) {
 		{"RepoManagement", caps.RepoManagement, false},
 		{"KeyManagement", caps.KeyManagement, false},
 		{"Groups", caps.Groups, false},
+		{"PackageUpgrade", caps.PackageUpgrade, false},
 	}
 	for _, c := range checks {
 		t.Run(c.name, func(t *testing.T) {

flatpak/flatpak_test.go

@@ -400,6 +400,9 @@ func TestCapabilities(t *testing.T) {
 	if caps.NameNormalize {
 		t.Error("expected NameNormalize=false")
 	}
+	if !caps.PackageUpgrade {
+		t.Error("expected PackageUpgrade=true")
+	}
 }
 
 func TestName(t *testing.T) {

pacman/pacman_test.go

@@ -173,6 +173,7 @@ func TestCapabilities(t *testing.T) {
 		{"RepoManagement", caps.RepoManagement, false},
 		{"KeyManagement", caps.KeyManagement, false},
 		{"NameNormalize", caps.NameNormalize, false},
+		{"PackageUpgrade", caps.PackageUpgrade, true},
 	}
 
 	for _, tt := range tests {

pkg/pkg_test.go

@@ -665,4 +665,7 @@ func TestCapabilities(t *testing.T) {
 	if caps.DryRun {
 		t.Error("expected DryRun=false")
 	}
+	if !caps.PackageUpgrade {
+		t.Error("expected PackageUpgrade=true")
+	}
 }

ports/ports_test.go

@@ -802,4 +802,7 @@ func TestCapabilities(t *testing.T) {
 	if caps.DryRun {
 		t.Error("expected DryRun=false")
 	}
+	if !caps.PackageUpgrade {
+		t.Error("expected PackageUpgrade=true")
+	}
 }

rpm/rpm_test.go

@@ -44,6 +44,7 @@ func TestGetCapabilities(t *testing.T) {
 		"KeyManagement":  caps.KeyManagement,
 		"Groups":         caps.Groups,
 		"DryRun":         caps.DryRun,
+		"PackageUpgrade": caps.PackageUpgrade,
 	}
 	for name, got := range wantFalse {
 		t.Run(name+"_false", func(t *testing.T) {

snap/snap_test.go

@@ -444,6 +444,9 @@ func TestCapabilities(t *testing.T) {
 	if caps.NameNormalize {
 		t.Error("expected NameNormalize=false")
 	}
+	if !caps.PackageUpgrade {
+		t.Error("expected PackageUpgrade=true")
+	}
 }
 
 func TestName(t *testing.T) {