Factor out logic to exclude sub-modules

pkg/config/config.go

@@ -528,6 +528,21 @@ func isAutoGenerated(path *pathlib.Path) (bool, error) {
 	return false, nil
 }
 
+func shouldExcludeModule(ctx context.Context, root *pathlib.Path, goModPath *pathlib.Path) (bool, error) {
+	log := zerolog.Ctx(ctx)
+	relative, err := goModPath.RelativeTo(root)
+	if err != nil {
+		return false, stackerr.NewStackErrf(err, "determining distance from search root")
+	}
+
+	if len(relative.Parts()) != 1 {
+		log.Debug().Msg("skipping sub-module")
+		return true, nil
+	}
+	log.Debug().Int("parts_len", len(relative.Parts())).Str("parts", fmt.Sprintf("%v", relative.Parts())).Msg("not skipping module as this is the root path")
+	return false, nil
+}
+
 func (c *Config) subPackages(
 	ctx context.Context,
 	pkgPath string,
@@ -587,16 +602,14 @@ func (c *Config) subPackages(
 			pathLog.Debug().Msg("path contains go.mod file")
 			// Check if our current depth is 0. We do this to skip sub-modules, but not
 			// the root module.
-			relative, err := path.RelativeTo(searchRoot)
+			shouldExclude, err := shouldExcludeModule(ctx, searchRoot, path)
 			if err != nil {
-				return stackerr.NewStackErrf(err, "determining distance from search root")
+				return err
 			}
 
-			if len(relative.Parts()) != 1 {
-				pathLog.Debug().Msg("skipping sub-module")
+			if shouldExclude {
 				return pathlib.ErrWalkSkipSubtree
 			}
-			pathLog.Debug().Int("parts_len", len(relative.Parts())).Str("parts", fmt.Sprintf("%v", relative.Parts())).Msg("not skipping module as this is the root path")
 		}
 
 		_, haveVisitedDir := visitedDirs[path.Parent().String()]
@@ -615,14 +628,20 @@ func (c *Config) subPackages(
 			}
 
 			pathLog.Debug().Msg("subdirectory has a .go file")
-			goModExists, err := path.Parent().Join("go.mod").Exists()
+			goModPath := path.Parent().Join("go.mod")
+			goModExists, err := goModPath.Exists()
 			if err != nil {
 				pathLog.Err(err).Msg("failed to determine if go.mod exists")
 				return err
 			}
 			if goModExists {
-				pathLog.Debug().Msg("found .go file, but go.mod exists. Skipping.")
-				return pathlib.ErrWalkSkipSubtree
+				shouldExclude, err := shouldExcludeModule(ctx, searchRoot, goModPath)
+				if err != nil {
+					return err
+				}
+				if shouldExclude {
+					return pathlib.ErrWalkSkipSubtree
+				}
 			}
 			subdirectoriesWithGoFiles = append(subdirectoriesWithGoFiles, path.Parent())
 			visitedDirs[path.Parent().String()] = nil