fix: preserve trailing slashes in import URLs

lib/dependency.ts

@@ -148,62 +148,64 @@
  */
 export async function resolveLatestVersion(
   dependency: Dependency,
+  options?: { cache?: boolean },
 ): Promise<UpdatedDependency | undefined> {
-  await LatestVersionCache.lock(dependency.name);
+  using cache = new LatestVersionCache(dependency.name);
+  if (options?.cache) {
+    const cached = cache.get(dependency.name);
+    if (cached) {
+      return { ...cached, path: dependency.path };
+    }
+    if (cached === null) {
+      // The dependency is already found to be up to date or unable to resolve.
+      return;
+    }
+  }
+  const constraint = dependency.version
+    ? SemVer.tryParseRange(dependency.version)
+    : undefined;
+  // Do not update inequality ranges.
+  if (constraint && constraint.flat().length > 1) {
+    return;
+  }
   const result = await _resolveLatestVersion(dependency);
-  LatestVersionCache.unlock(dependency.name);
+  if (options?.cache) {
+    cache.set(dependency.name, result ?? null);
+  }
   return result;
 }
 
-class LatestVersionCache {
+class LatestVersionCache implements Disposable {
   static #mutex = new Map<string, Mutex>();
   static #cache = new Map<string, UpdatedDependency | null>();
 
-  static lock(name: string): Promise<void> {
-    const mutex = this.#mutex.get(name) ??
-      this.#mutex.set(name, new Mutex()).get(name)!;
-    return mutex.acquire();
-  }
-
-  static unlock(name: string): void {
-    const mutex = this.#mutex.get(name);
-    assertExists(mutex);
-    mutex.release();
+  constructor(readonly name: string) {
+    const mutex = LatestVersionCache.#mutex.get(name) ??
+      LatestVersionCache.#mutex.set(name, new Mutex()).get(name)!;
+    mutex.acquire();
   }
 
-  static get(name: string): UpdatedDependency | null | undefined {
-    return this.#cache.get(name);
+  get(name: string): UpdatedDependency | null | undefined {
+    return LatestVersionCache.#cache.get(name);
   }
 
-  static set<T extends UpdatedDependency | null>(
+  set<T extends UpdatedDependency | null>(
     name: string,
     dependency: T,
-  ): T {
-    this.#cache.set(name, dependency);
-    return dependency;
+  ): void {
+    LatestVersionCache.#cache.set(name, dependency);
+  }
+
+  [Symbol.dispose]() {
+    const mutex = LatestVersionCache.#mutex.get(this.name);
+    assertExists(mutex);
+    mutex.release();
   }
 }
 
 async function _resolveLatestVersion(
   dependency: Dependency,
 ): Promise<UpdatedDependency | undefined> {
-  const cached = LatestVersionCache.get(dependency.name);
-  if (cached) {
-    return { ...cached, path: dependency.path };
-  }
-  if (cached === null) {
-    // The dependency is already found to be up to date or unable to resolve.
-    return;
-  }
-  const constraint = dependency.version
-    ? SemVer.tryParseRange(dependency.version)
-    : undefined;
-
-  // Do not update inequality ranges.
-  if (constraint && constraint.flat().length > 1) {
-    return;
-  }
-
   switch (dependency.protocol) {
     case "npm:": {
       const response = await fetch(
@@ -221,10 +223,7 @@
       if (latest === dependency.version || isPreRelease(latest)) {
         break;
       }
-      return LatestVersionCache.set(
-        dependency.name,
-        { ...dependency, version: latest },
-      );
+      return { ...dependency, version: latest };
     }
     // Ref: https://jsr.io/docs/api#jsr-registry-api
     case "jsr:": {
@@ -248,10 +247,7 @@
       if (latest === dependency.version || isPreRelease(latest)) {
         break;
       }
-      return LatestVersionCache.set(
-        dependency.name,
-        { ...dependency, version: latest },
-      );
+      return { ...dependency, version: latest };
     }
     case "http:":
     case "https:": {
@@ -263,17 +259,19 @@
       if (!response.redirected) {
         break;
       }
-      const latest = parse(response.url);
-      if (!latest.version || isPreRelease(latest.version)) {
+      const redirected = parse(response.url);
+      if (!redirected.version || isPreRelease(redirected.version)) {
         break;
       }
-      return LatestVersionCache.set(
-        dependency.name,
-        latest as UpdatedDependency,
-      );
+      const latest = redirected as UpdatedDependency;
+      return {
+        ...latest,
+        // Preserve the original path if it is the root, which is unlikely to be
+        // included in the redirected URL.
+        path: dependency.path === "/" ? "/" : latest.path,
+      };
     }
   }
-  LatestVersionCache.set(dependency.name, null);
 }
 
 const isNpmPackageMeta = is.ObjectOf({

lib/testing.ts

@@ -154,7 +154,9 @@ function parseDenoLandUrl(url: URL) {
   return {
     name: std ? "deno.land/std" : `deno.land/x/${name}`,
     version,
-    path,
+    // Remove a trailing slash if it exists to imitate the behavior of typical
+    // Web servers.
+    path: path.replace(/\/$/, ""),
   };
 }
 

lib/update.ts

@@ -71,6 +71,11 @@ class DenoGraph {
 }
 
 export interface CollectOptions {
+  /**
+   * Whether to use the cache to resolve dependencies.
+   * @default true
+   */
+  cache?: boolean;
   /**
    * The working directory to resolve relative paths.
    * If not specified, the current working directory is used.
@@ -167,7 +172,7 @@ export async function collect(
         const update = await _createDependencyUpdate(
           dependency,
           mod.specifier,
-          { ...options, importMap },
+          { cache: true, ...options, importMap },
         );
         if (update) updates.push(update);
       })
@@ -218,7 +223,7 @@ const load: NonNullable<CreateGraphOptions["load"]> = async (
 async function _createDependencyUpdate(
   dependencyJson: DependencyJson,
   referrer: string,
-  options?: Pick<CollectOptions, "ignore" | "only"> & {
+  options?: Pick<CollectOptions, "cache" | "ignore" | "only"> & {
     importMap?: ImportMap;
   },
 ): Promise<DependencyUpdate | undefined> {
@@ -243,7 +248,9 @@ async function _createDependencyUpdate(
   if (options?.only && !options.only(dependency)) {
     return;
   }
-  const latest = await resolveLatestVersion(dependency);
+  const latest = await resolveLatestVersion(dependency, {
+    cache: options?.cache,
+  });
   if (!latest || latest.version === dependency.version) {
     return;
   }
@@ -256,7 +263,7 @@ async function _createDependencyUpdate(
     );
   }
   return {
-    from: dependency,
+    from: normalizeWithUpdated(dependency, latest),
     to: latest,
     code: {
       // We prefer to put the original specifier here.
@@ -275,7 +282,7 @@ async function _createDependencyUpdate(
 
 async function _collectFromImportMap(
   specifier: ModuleJson["specifier"],
-  options: Pick<CollectOptions, "ignore" | "only">,
+  options: Pick<CollectOptions, "cache" | "ignore" | "only">,
 ): Promise<DependencyUpdate[]> {
   const json = await readImportMapJson(new URL(specifier));
   const updates: DependencyUpdate[] = [];
@@ -292,12 +299,14 @@ async function _collectFromImportMap(
         if (options.only && !options.only(dependency)) {
           return;
         }
-        const latest = await resolveLatestVersion(dependency);
+        const latest = await resolveLatestVersion(dependency, {
+          cache: options.cache,
+        });
         if (!latest || latest.version === dependency.version) {
           return;
         }
         updates.push({
-          from: dependency,
+          from: normalizeWithUpdated(dependency, latest),
           to: latest,
           code: {
             specifier: value,
@@ -317,6 +326,19 @@ async function _collectFromImportMap(
   return updates;
 }
 
+function normalizeWithUpdated(
+  dependency: Dependency,
+  updated: UpdatedDependency,
+): Dependency {
+  if (dependency.version) {
+    return dependency;
+  }
+  return {
+    ...updated,
+    version: undefined,
+  };
+}
+
 export type VersionChange = {
   from?: string;
   to: string;

lib/update_test.ts

@@ -13,6 +13,7 @@ async function test(
 ) {
   try {
     const updates = await collect(new URL(path, import.meta.url), {
+      cache: false,
       cwd: new URL(dirname(path), import.meta.url),
     });
     Deno.test(

test/snapshots/file_test.ts.snap

@@ -1159,9 +1159,10 @@ snapshot[`associateByFile - unversioned.ts 1`] = `
           specifier: "https://deno.land/std/assert/assert.ts",
         },
         from: {
-          name: "deno.land/std/assert/assert.ts",
-          path: "",
+          name: "deno.land/std",
+          path: "/assert/assert.ts",
           protocol: "https:",
+          version: undefined,
         },
         map: undefined,
         to: {

test/snapshots/update_test.ts.snap

@@ -865,9 +865,10 @@ snapshot[`collect - unversioned.ts 1`] = `
     specifier: "https://deno.land/std/assert/assert.ts",
   },
   from: {
-    name: "deno.land/std/assert/assert.ts",
-    path: "",
+    name: "deno.land/std",
+    path: "/assert/assert.ts",
     protocol: "https:",
+    version: undefined,
   },
   to: {
     name: "deno.land/std",