Broke out the tag filtering logic to its own file

suite.go

@@ -812,33 +812,3 @@ func applyTagFilter(tags string, ft *feature) {
 
 	ft.pickles = pickles
 }
-
-// based on http://behat.readthedocs.org/en/v2.5/guides/6.cli.html#gherkin-filters
-func matchesTags(filter string, tags []*messages.Pickle_PickleTag) (ok bool) {
-	ok = true
-	for _, andTags := range strings.Split(filter, "&&") {
-		var okComma bool
-		for _, tag := range strings.Split(andTags, ",") {
-			tag = strings.Replace(strings.TrimSpace(tag), "@", "", -1)
-			if tag[0] == '~' {
-				tag = tag[1:]
-				okComma = !hasTag(tags, tag) || okComma
-			} else {
-				okComma = hasTag(tags, tag) || okComma
-			}
-		}
-		ok = ok && okComma
-	}
-	return
-}
-
-func hasTag(tags []*messages.Pickle_PickleTag, tag string) bool {
-	for _, t := range tags {
-		tName := strings.Replace(t.Name, "@", "", -1)
-
-		if tName == tag {
-			return true
-		}
-	}
-	return false
-}

tag_filter.go

@@ -0,0 +1,42 @@
+package godog
+
+import (
+	"strings"
+
+	"github.com/cucumber/messages-go/v10"
+)
+
+// based on http://behat.readthedocs.org/en/v2.5/guides/6.cli.html#gherkin-filters
+func matchesTags(filter string, tags []*messages.Pickle_PickleTag) (ok bool) {
+	ok = true
+
+	for _, andTags := range strings.Split(filter, "&&") {
+		var okComma bool
+
+		for _, tag := range strings.Split(andTags, ",") {
+			tag = strings.Replace(strings.TrimSpace(tag), "@", "", -1)
+
+			okComma = hasTag(tags, tag) || okComma
+			if tag[0] == '~' {
+				tag = tag[1:]
+				okComma = !hasTag(tags, tag) || okComma
+			}
+		}
+
+		ok = ok && okComma
+	}
+
+	return
+}
+
+func hasTag(tags []*messages.Pickle_PickleTag, tag string) bool {
+	for _, t := range tags {
+		tName := strings.Replace(t.Name, "@", "", -1)
+
+		if tName == tag {
+			return true
+		}
+	}
+
+	return false
+}

tag_filter_test.go

@@ -6,13 +6,13 @@ import (
 	"github.com/cucumber/messages-go/v10"
 )
 
-func assertNotMatchesTagFilter(tags []*messages.Pickle_PickleTag, filter string, t *testing.T) {
+func assertNotMatchesTagFilter(tags []*tag, filter string, t *testing.T) {
 	if matchesTags(filter, tags) {
 		t.Errorf(`expected tags: %v not to match tag filter "%s", but it did`, tags, filter)
 	}
 }
 
-func assertMatchesTagFilter(tags []*messages.Pickle_PickleTag, filter string, t *testing.T) {
+func assertMatchesTagFilter(tags []*tag, filter string, t *testing.T) {
 	if !matchesTags(filter, tags) {
 		t.Errorf(`expected tags: %v to match tag filter "%s", but it did not`, tags, filter)
 	}