fix

internal/extinctions/extinctions.go

@@ -11,7 +11,7 @@ import (
 func CheckExtinctions(opts options.Options, builder *refs.ReferenceSummaryBuilder) error {
 	gha.StartLogGroup("Checking for extinctions...")
 	defer gha.EndLogGroup()
-	flagKeys := make([]string, 0, len(builder.RemovedFlagKeys()))
+	flagKeys := builder.RemovedFlagKeys()
 
 	matcher, err := search.GetMatcher(opts, flagKeys, nil)
 	if err != nil {

internal/references/builder_test.go

@@ -6,7 +6,7 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-func TestBuilder(t *testing.T) {
+func TestBuilder_Build(t *testing.T) {
 	ref := ReferenceSummaryBuilder{
 		flagsAdded: map[string][]string{
 			"flag1": {"alias1"},
@@ -35,3 +35,31 @@ func TestBuilder(t *testing.T) {
 	assert.Len(t, built.FlagsRemoved, 2)
 	assert.Len(t, built.ExtinctFlags, 1)
 }
+
+func TestBuilder_RemovedFlagKeys(t *testing.T) {
+	ref := ReferenceSummaryBuilder{
+		flagsAdded: map[string][]string{
+			"flag1": {"alias1"},
+			"flag2": {"alias2"},
+		},
+		flagsRemoved: map[string][]string{
+			"flag2": {},
+			"flag3": {"alias3"},
+			"flag4": {"alias4"},
+		},
+		flagsFoundAtHead: map[string]struct{}{
+			"flag3": {},
+		},
+		foundFlags: map[string]struct{}{
+			"flag1": {},
+			"flag2": {},
+			"flag3": {},
+			"flag4": {},
+		},
+		includeExtinctions: true,
+	}
+
+	keys := ref.RemovedFlagKeys()
+
+	assert.Len(t, keys, 3)
+}