fix handling the root paths for serving files

also adds a helper HandleFiles and a bunch of tests to make sure all works

.golangci.yml

@@ -1,6 +1,6 @@
 linters-settings:
   govet:
-    check-shadowing: true
+    shadow: true
   gocyclo:
     min-complexity: 15
   maligned:
@@ -22,35 +22,38 @@ linters-settings:
 
 linters:
   enable:
-    - megacheck
+    - staticcheck
     - revive
     - govet
     - unconvert
-    - gas
+    - gosec
     - misspell
     - unparam
     - typecheck
     - ineffassign
     - stylecheck
     - gochecknoinits
-    - exportloopref
+    - copyloopvar
     - gocritic
     - nakedret
     - gosimple
     - prealloc
+    - unused
   fast: false
   disable-all: true
 
-run:
-  output:
-    format: tab
-  skip-dirs:
-    - vendor
 
+run:
+  concurrency: 4
 
 issues:
   exclude-rules:
     - text: "G114: Use of net/http serve function that has no support for setting timeouts"
       linters:
         - gosec
+    - linters:
+        - unparam
+        - revive
+      path: _test\.go$
+      text: "unused-parameter"
   exclude-use-default: false

group.go

@@ -5,6 +5,7 @@ package routegroup
 import (
 	"net/http"
 	"regexp"
+	"strings"
 	"sync"
 )
 
@@ -96,9 +97,40 @@ func (b *Bundle) With(middleware func(http.Handler) http.Handler, more ...func(h
 
 // Handle adds a new route to the Group's mux, applying all middlewares to the handler.
 func (b *Bundle) Handle(pattern string, handler http.Handler) {
+	// for file server paths (ending with /), preserve the pattern and disable root not-found handler
+	if strings.HasSuffix(pattern, "/") {
+		if pattern == "/" {
+			b.rootRegistered.disableRootNotFoundHandler = true
+		}
+		fullPath := b.basePath + pattern
+		b.mux.Handle(fullPath, b.wrapMiddleware(handler))
+		return
+	}
 	b.register(pattern, handler.ServeHTTP)
 }
 
+// HandleFiles is a helper to serve static files from a directory
+func (b *Bundle) HandleFiles(pattern string, root http.FileSystem) {
+	// normalize pattern to always have trailing slash
+	if !strings.HasSuffix(pattern, "/") {
+		pattern += "/"
+	}
+
+	// build the full path for registration
+	fullPath := b.basePath + pattern
+
+	if pattern == "/" && b.basePath == "" {
+		// root case - serve directly without stripping
+		b.rootRegistered.disableRootNotFoundHandler = true
+		b.mux.Handle("/", b.wrapMiddleware(http.FileServer(root)))
+		return
+	}
+
+	// for both mounted groups and prefixed paths, strip the fullPath
+	handler := http.StripPrefix(strings.TrimSuffix(fullPath, "/"), http.FileServer(root))
+	b.mux.Handle(fullPath, b.wrapMiddleware(handler))
+}
+
 // HandleFunc registers the handler function for the given pattern to the Group's mux.
 // The handler is wrapped with the Group's middlewares.
 func (b *Bundle) HandleFunc(pattern string, handler http.HandlerFunc) {