refactor: move mergePaths() to utils.ts (#2905)

Author: timreichen

src/app.ts

@@ -7,12 +7,7 @@ import { DENO_DEPLOYMENT_ID } from "./runtime/build_id.ts";
 import * as colors from "@std/fmt/colors";
 import { type MiddlewareFn, runMiddlewares } from "./middlewares/mod.ts";
 import { FreshReqContext } from "./context.ts";
-import {
-  mergePaths,
-  type Method,
-  type Router,
-  UrlPatternRouter,
-} from "./router.ts";
+import { type Method, type Router, UrlPatternRouter } from "./router.ts";
 import {
   type FreshConfig,
   normalizeConfig,
@@ -22,6 +17,7 @@ import { type BuildCache, ProdBuildCache } from "./build_cache.ts";
 import type { ServerIslandRegistry } from "./context.ts";
 import { FinishSetup, ForgotBuild } from "./finish_setup.tsx";
 import { HttpError } from "./error.ts";
+import { mergePaths } from "./utils.ts";
 
 // TODO: Completed type clashes in older Deno versions
 // deno-lint-ignore no-explicit-any

src/router.ts

@@ -28,17 +28,6 @@ export interface Router<T> {
 
 export const IS_PATTERN = /[*:{}+?()]/;
 
-export function mergePaths(a: string, b: string) {
-  if (a === "" || a === "/" || a === "/*") return b;
-  if (b === "/") return a;
-  if (a.endsWith("/")) {
-    return a.slice(0, -1) + b;
-  } else if (!b.startsWith("/")) {
-    return a + "/" + b;
-  }
-  return a + b;
-}
-
 export class UrlPatternRouter<T> implements Router<T> {
   readonly _routes: Route<T>[] = [];
   readonly _middlewares: T[] = [];

src/router_test.ts

@@ -1,10 +1,5 @@
 import { expect } from "@std/expect";
-import {
-  IS_PATTERN,
-  mergePaths,
-  pathToPattern,
-  UrlPatternRouter,
-} from "./router.ts";
+import { IS_PATTERN, pathToPattern, UrlPatternRouter } from "./router.ts";
 
 Deno.test("IS_PATTERN", () => {
   expect(IS_PATTERN.test("/foo")).toEqual(false);
@@ -176,12 +171,3 @@ Deno.test("pathToPattern", async (t) => {
     expect(() => pathToPattern("foo/[[name]]-bar")).toThrow();
   });
 });
-
-Deno.test("mergePaths", () => {
-  expect(mergePaths("", "")).toEqual("");
-  expect(mergePaths("/", "/foo")).toEqual("/foo");
-  expect(mergePaths("/*", "/foo")).toEqual("/foo");
-  expect(mergePaths("/foo/bar", "/baz")).toEqual("/foo/bar/baz");
-  expect(mergePaths("/foo/bar/", "/baz")).toEqual("/foo/bar/baz");
-  expect(mergePaths("/foo/bar", "baz")).toEqual("/foo/bar/baz");
-});

src/utils.ts

@@ -13,3 +13,22 @@ export function assertInDir(
     throw new Error(`Path "${tmp}" resolved outside of "${dir}"`);
   }
 }
+
+/**
+ * Joins two path segments into a single normalized path.
+ * @example
+ * ```ts
+ * mergePaths("/api", "users");       // "/api/users"
+ * mergePaths("/api/", "/users");     // "/api/users"
+ * mergePaths("/", "/users");         // "/users"
+ * mergePaths("", "/users");          // "/users"
+ * mergePaths("/api", "/users");      // "/api/users"
+ * ```
+ */
+export function mergePaths(a: string, b: string) {
+  if (a === "" || a === "/" || a === "/*") return b;
+  if (b === "/") return a;
+  if (a.endsWith("/")) return a.slice(0, -1) + b;
+  if (!b.startsWith("/")) return a + "/" + b;
+  return a + b;
+}

src/utils_test.ts

@@ -0,0 +1,11 @@
+import { expect } from "@std/expect";
+import { mergePaths } from "./utils.ts";
+
+Deno.test("mergePaths", () => {
+  expect(mergePaths("", "")).toEqual("");
+  expect(mergePaths("/", "/foo")).toEqual("/foo");
+  expect(mergePaths("/*", "/foo")).toEqual("/foo");
+  expect(mergePaths("/foo/bar", "/baz")).toEqual("/foo/bar/baz");
+  expect(mergePaths("/foo/bar/", "/baz")).toEqual("/foo/bar/baz");
+  expect(mergePaths("/foo/bar", "baz")).toEqual("/foo/bar/baz");
+});