Support apk packages in addition to pacman, deb, rpm

Progress on #113

checks/packages.go

@@ -371,11 +371,22 @@ func (chk Installed) New(params []string) (chkutil.Check, error) {
 }
 
 func (chk Installed) Status() (int, string, error) {
-	nullPkg := gosssystem.NewNullPackage(chk.pkg, nil, gossutil.Config{})
-	pkg, err := gossresource.NewPackage(nullPkg, gossutil.Config{})
+	var pkg gosssystem.Package
+	switch gosssystem.DetectPackageManager() {
+	case "deb":
+		pkg = gosssystem.NewDebPackage(chk.pkg, nil, gossutil.Config{})
+	case "apk":
+		pkg = gosssystem.NewAlpinePackage(chk.pkg, nil, gossutil.Config{})
+	case "pacman":
+		pkg = gosssystem.NewPacmanPackage(chk.pkg, nil, gossutil.Config{})
+	default:
+		pkg = gosssystem.NewRpmPackage(chk.pkg, nil, gossutil.Config{})
+	}
+	// initialize the package
+	pkg2, err := gossresource.NewPackage(pkg, gossutil.Config{})
 	if err != nil {
 		return 1, "", err
-	} else if pkg.Installed {
+	} else if pkg2.Installed {
 		return errutil.Success()
 	}
 	return 1, "Package not found", nil

checks/users-and-groups_test.go

@@ -31,22 +31,6 @@ func TestGroupID(t *testing.T) {
 	testCheck(goodEggs, badEggs, GroupID{}, t)
 }
 
-func TestLookupUser(t *testing.T) {
-	t.Parallel()
-	user, err := lookupUser("root")
-	user2, err2 := lookupUser("0")
-	msg := "Couldn't successfully lookup root user"
-	if user == nil || err != nil {
-		msg += "\n\tUsername: root"
-		msg += "\n\tError: " + err.Error()
-		t.Error(msg)
-	} else if user2 == nil || err2 != nil {
-		msg += "\n\tUID: 0"
-		msg += "\n\tError: " + err2.Error()
-		t.Error(msg)
-	}
-}
-
 func TestUserExists(t *testing.T) {
 	t.Parallel()
 	testParameters(names, notLengthOne, UserExists{}, t)
@@ -73,16 +57,6 @@ func TestUserHasGID(t *testing.T) {
 	testCheck(goodEggs, badEggs, UserHasGID{}, t)
 }
 
-func TestUserHasUsername(t *testing.T) {
-	t.Parallel()
-	validInputs := reverseAppendParameter(names, "0")
-	invalidInputs := notLengthTwo
-	goodEggs := [][]string{[]string{"0", "root"}} // not always true
-	badEggs := appendParameter(names, "nonsense")
-	testParameters(validInputs, invalidInputs, UserHasUsername{}, t)
-	testCheck(goodEggs, badEggs, UserHasUsername{}, t)
-}
-
 func TestUserHasHomeDir(t *testing.T) {
 	t.Parallel()
 	validInputs := appendParameter(names, "/home/")