td: Track deleted files. (#724)

This commit updates the target determination to track deleted files.
Mats pointed out that someone could delete a manifest and get a passsing
build. The original thought was that we wouldn't need to build an app if
it was deleted, which is still true. This change returns all changes
including deletes, and validates the directory still exists before
returning it as a target.

cmd/community/targetdeterminator.go

@@ -47,6 +47,8 @@ func determineTargets(cmd *cobra.Command, args []string) error {
 
 	changedApps := map[string]bool{}
 	for _, f := range changedFiles {
+		dir := filepath.Dir(f) + string(os.PathSeparator)
+
 		// We only care about things in apps/{{ app package }}/ changing and
 		// nothing else. Skip any file changes that are not in that structure.
 		parts := strings.Split(f, string(os.PathSeparator))
@@ -56,10 +58,17 @@ func determineTargets(cmd *cobra.Command, args []string) error {
 
 		// If the filepath does not start with apps, we also don't care about
 		// it.
-		dir := filepath.Dir(f) + string(os.PathSeparator)
-		if strings.HasPrefix(dir, "apps") {
-			changedApps[dir] = true
+		if !strings.HasPrefix(dir, "apps") {
+			continue
 		}
+
+		// If the directory no longer exists, we don't care about it. This would
+		// happen if someone deleted an app in a PR.
+		if !dirExists(dir) {
+			continue
+		}
+
+		changedApps[dir] = true
 	}
 
 	for app := range changedApps {
@@ -68,3 +77,16 @@ func determineTargets(cmd *cobra.Command, args []string) error {
 
 	return nil
 }
+
+func dirExists(dir string) bool {
+	_, err := os.Stat(dir)
+	if os.IsNotExist(err) {
+		return false
+	}
+
+	if err != nil {
+		return false
+	}
+
+	return true
+}

tools/repo/repo.go

@@ -7,7 +7,6 @@ import (
 	"github.com/go-git/go-git/v5"
 	"github.com/go-git/go-git/v5/plumbing"
 	"github.com/go-git/go-git/v5/plumbing/object"
-	"github.com/go-git/go-git/v5/utils/merkletrie"
 )
 
 // IsInRepo determines if the provided directory is in the provided git
@@ -106,16 +105,6 @@ func DetermineChanges(dir string, oldCommit string, newCommit string) ([]string,
 	// Create a unique list of changed files.
 	changedFiles := []string{}
 	for _, change := range changes {
-		action, err := change.Action()
-		if err != nil {
-			return nil, fmt.Errorf("couldn't determine action for commit: %w", err)
-		}
-
-		// Skip deleted files.
-		if action == merkletrie.Delete {
-			continue
-		}
-
 		changedFiles = append(changedFiles, getChangeName(change))
 	}
 
@@ -125,11 +114,11 @@ func DetermineChanges(dir string, oldCommit string, newCommit string) ([]string,
 func getChangeName(change *object.Change) string {
 	var empty = object.ChangeEntry{}
 
-	// Given we skip deletes, this should never be empty. To should be populated
-	// on inserts and modifications.
+	// Use the To field for Inserts and Modifications.
 	if change.To != empty {
 		return change.To.Name
 	}
 
+	// The From field for Deletes.
 	return change.From.Name
 }