fix: only strip a whole index segment in the fs router

.changeset/fs-router-index-suffix.md

@@ -0,0 +1,5 @@
+---
+"@solidjs/start": patch
+---
+
+Only strip a whole `index` segment when mapping route files to paths. Route files whose names merely end in "index", such as `routes/reindex.tsx`, were previously served at `/re` instead of `/reindex`.

packages/start/src/config/fs-router.ts

@@ -7,23 +7,33 @@ import {
   type FileSystemRouterConfig,
 } from "./fs-routes/router.ts";
 
+/**
+ * Maps a route file to its router path: strips the routes directory and extension,
+ * drops a trailing `index` segment (`blog/index` -> `/blog/`, `index` -> `/`) and
+ * converts `[param]`, `[[optional]]` and `[...rest]` segments to router syntax.
+ */
+function toRoutePath(src: string, config: FileSystemRouterConfig) {
+  const routePath = cleanPath(src, config)
+    // remove the initial slash
+    .slice(1)
+    // only strip a whole `index` segment, not a name that merely ends in "index" (e.g. `reindex`)
+    .replace(/(^|\/)index$/, "$1")
+    .replace(/\[([^/]+)\]/g, (_, m) => {
+      if (m.length > 3 && m.startsWith("...")) {
+        return `*${m.slice(3)}`;
+      }
+      if (m.length > 2 && m.startsWith("[") && m.endsWith("]")) {
+        return `:${m.slice(1, -1)}?`;
+      }
+      return `:${m}`;
+    });
+
+  return routePath.length > 0 ? `/${routePath}` : "/";
+}
+
 export class SolidStartClientFileRouter extends BaseFileSystemRouter {
   toPath(src: string) {
-    const routePath = cleanPath(src, this.config)
-      // remove the initial slash
-      .slice(1)
-      .replace(/index$/, "")
-      .replace(/\[([^/]+)\]/g, (_, m) => {
-        if (m.length > 3 && m.startsWith("...")) {
-          return `*${m.slice(3)}`;
-        }
-        if (m.length > 2 && m.startsWith("[") && m.endsWith("]")) {
-          return `:${m.slice(1, -1)}?`;
-        }
-        return `:${m}`;
-      });
-
-    return routePath?.length > 0 ? `/${routePath}` : "/";
+    return toRoutePath(src, this.config);
   }
 
   toRoute(src: string) {
@@ -107,21 +117,7 @@ export class SolidStartServerFileRouter extends BaseFileSystemRouter {
   }
 
   toPath(src: string) {
-    const routePath = cleanPath(src, this.config)
-      // remove the initial slash
-      .slice(1)
-      .replace(/index$/, "")
-      .replace(/\[([^/]+)\]/g, (_, m) => {
-        if (m.length > 3 && m.startsWith("...")) {
-          return `*${m.slice(3)}`;
-        }
-        if (m.length > 2 && m.startsWith("[") && m.endsWith("]")) {
-          return `:${m.slice(1, -1)}?`;
-        }
-        return `:${m}`;
-      });
-
-    return routePath?.length > 0 ? `/${routePath}` : "/";
+    return toRoutePath(src, this.config);
   }
 
   toRoute(src: string) {

packages/start/src/config/fs-routes/router.spec.ts

@@ -3,7 +3,7 @@ import os from "node:os";
 import path from "node:path";
 import { afterEach, describe, expect, it } from "vitest";
 
-import { SolidStartClientFileRouter } from "../fs-router.ts";
+import { SolidStartClientFileRouter, SolidStartServerFileRouter } from "../fs-router.ts";
 import { analyzeModule } from "./router.ts";
 
 const temporaryDirectories: string[] = [];
@@ -83,3 +83,37 @@ describe("analyzeModule", () => {
     expect(router.toRoute(route)?.$component.pick).toEqual(["default", "$css"]);
   });
 });
+
+describe("toPath", () => {
+  const dir = "/app/src/routes";
+  const routers = [SolidStartClientFileRouter, SolidStartServerFileRouter];
+
+  it.each([
+    ["index.tsx", "/"],
+    ["blog/index.tsx", "/blog/"],
+    ["[id]/index.tsx", "/:id/"],
+    ["about.tsx", "/about"],
+    ["blog/[slug].tsx", "/blog/:slug"],
+    ["docs/[[version]].tsx", "/docs/:version?"],
+    ["[...404].tsx", "/*404"],
+  ])("maps %s to %s", (file, expected) => {
+    for (const Router of routers) {
+      const router = new Router({ dir, extensions: ["tsx"] });
+      expect(router.toPath(`${dir}/${file}`)).toBe(expected);
+    }
+  });
+
+  // https://github.com/solidjs/solid-start/issues/2314
+  it.each([
+    ["reindex.tsx", "/reindex"],
+    ["myindex.tsx", "/myindex"],
+    ["appendix.tsx", "/appendix"],
+    ["reindex/index.tsx", "/reindex/"],
+    ["blog/reindex.tsx", "/blog/reindex"],
+  ])("does not strip a trailing index substring from %s", (file, expected) => {
+    for (const Router of routers) {
+      const router = new Router({ dir, extensions: ["tsx"] });
+      expect(router.toPath(`${dir}/${file}`)).toBe(expected);
+    }
+  });
+});