Avoid returning always nil error in strict filterset

internal/processor/filterset/config.go

@@ -50,7 +50,7 @@ func CreateFilterSet(filters []string, cfg *Config) (FilterSet, error) {
 		return regexp.NewFilterSet(filters, cfg.RegexpConfig)
 	case Strict:
 		// Strict FilterSets do not have any extra configuration options, so call the constructor directly.
-		return strict.NewFilterSet(filters)
+		return strict.NewFilterSet(filters), nil
 	default:
 		return nil, fmt.Errorf("unrecognized %v: '%v', valid types are: %v", MatchTypeFieldName, cfg.MatchType, validMatchTypes)
 	}

internal/processor/filterset/strict/strictfilterset.go

@@ -24,24 +24,20 @@ type FilterSet struct {
 }
 
 // NewFilterSet constructs a FilterSet of exact string matches.
-func NewFilterSet(filters []string) (*FilterSet, error) {
+func NewFilterSet(filters []string) *FilterSet {
 	fs := &FilterSet{
 		filters: make(map[string]struct{}, len(filters)),
 	}
 
-	fs.addFilters(filters)
-	return fs, nil
+	for _, f := range filters {
+		fs.filters[f] = struct{}{}
+	}
+
+	return fs
 }
 
 // Matches returns true if the given string matches any of the FilterSet's filters.
 func (sfs *FilterSet) Matches(toMatch string) bool {
 	_, ok := sfs.filters[toMatch]
 	return ok
 }
-
-// addFilters all the given filters.
-func (sfs *FilterSet) addFilters(filters []string) {
-	for _, f := range filters {
-		sfs.filters[f] = struct{}{}
-	}
-}

internal/processor/filterset/strict/strictfilterset_test.go

@@ -43,17 +43,15 @@ func TestNewStrictFilterSet(t *testing.T) {
 
 	for _, test := range tests {
 		t.Run(test.name, func(t *testing.T) {
-			fs, err := NewFilterSet(test.filters)
+			fs := NewFilterSet(test.filters)
 			assert.Equal(t, test.success, fs != nil)
-			assert.Equal(t, test.success, err == nil)
 		})
 	}
 }
 
 func TestStrictMatches(t *testing.T) {
-	fs, err := NewFilterSet(validStrictFilters)
+	fs := NewFilterSet(validStrictFilters)
 	assert.NotNil(t, fs)
-	assert.NoError(t, err)
 
 	matches := []string{
 		"exact_string_match",