refactor(lib): toRelativeSpecifier

- check if `url` is inside of `parent` directory

Signed-off-by: Lexus Drumgold <[email protected]>

package.json

@@ -123,7 +123,7 @@
     "prepublishOnly": "toggle-scripts -prepack",
     "release": "bash ./scripts/release.sh",
     "remark": "remark .",
-    "test": "cross-env NODE_OPTIONS=\"--conditions mlly --experimental-strip-types --experimental-transform-types\" vitest run",
+    "test": "yarn clean:build; cross-env NODE_OPTIONS=\"--conditions mlly --experimental-strip-types --experimental-transform-types\" vitest run",
     "test:cov": "yarn test --coverage",
     "test:cov:reports": "yarn test:cov --merge-reports --mode=reports",
     "test:cov:ui": "yarn test:ui --coverage",

src/lib/__tests__/to-relative-specifier.spec.mts

@@ -4,18 +4,35 @@
  */
 
 import testSubject from '#lib/to-relative-specifier'
+import type { ModuleId } from '@flex-development/mlly'
 import pathe from '@flex-development/pathe'
 
 describe('unit:lib/toRelativeSpecifier', () => {
-  it.each<Parameters<typeof testSubject>>([
+  it.each<[...Parameters<typeof testSubject>, (ModuleId)?]>([
+    [import.meta.url, import.meta.url],
+    [
+      pathe.pathToFileURL('__fixtures__/conditions.mts'),
+      pathe.pathToFileURL('src/lib/__tests__/resolver.spec.mts')
+    ],
     [
       pathe.pathToFileURL('src/lib'),
-      pathe.pathToFileURL('src/lib/resolve-alias.mts')
+      pathe.pathToFileURL('src/lib/to-relative-specifier.mts'),
+      pathe.pathToFileURL('src/lib/')
+    ],
+    [
+      pathe.pathToFileURL('src/lib/to-relative-specifier.mts'),
+      pathe.pathToFileURL('src/lib/index.mts')
     ],
-    [pathe.pathToFileURL('src/lib/cwd'), pathe.pathToFileURL('src/lib')],
-    [pathe.pathToFileURL('src/lib/to-relative-specifier'), import.meta.url],
-    [pathe.pathToFileURL('src/utils'), pathe.pathToFileURL('src/utils')]
-  ])('should return relative specifier (%#)', (url, parent) => {
-    expect(testSubject(url, parent)).toMatchSnapshot()
+    [pathe.pathToFileURL('src/lib/to-relative-specifier.mts'), import.meta.url],
+    [
+      pathe.pathToFileURL('src/lib/to-relative-specifier.mts'),
+      pathe.pathToFileURL('src/lib/')
+    ]
+  ])('should return relative specifier (%#)', (url, parent, expected = url) => {
+    // Act
+    const result = testSubject(url, parent)
+
+    // Expect
+    expect(String(new URL(result, parent))).to.eq(String(expected))
   })
 })

src/lib/to-relative-specifier.mts

@@ -3,9 +3,9 @@
  * @module mlly/lib/toRelativeSpecifier
  */
 
-import toUrl from '#lib/to-url'
 import type { ModuleId } from '@flex-development/mlly'
 import pathe from '@flex-development/pathe'
+import { ok } from 'devlop'
 
 /**
  * Turn `url` into a *relative specifier*.
@@ -26,24 +26,41 @@ import pathe from '@flex-development/pathe'
  *  Relative specifier
  */
 function toRelativeSpecifier(url: ModuleId, parent: ModuleId): string {
+  parent = pathe.fileURLToPath(parent)
+  url = pathe.fileURLToPath(url)
+
+  /**
+   * Directory name of {@linkcode parent} path.
+   *
+   * @const {string} dirname
+   */
+  const dirname: string = pathe.dirname(parent)
+
   /**
    * Relative specifier.
    *
    * @var {string} specifier
    */
-  let specifier: string = pathe.relative(
-    pathe.fileURLToPath(toUrl(parent)),
-    pathe.fileURLToPath(toUrl(url))
-  )
-
-  if (/(?:\.\.\/){2,}/.test(specifier)) {
-    specifier = specifier.slice(specifier.indexOf(pathe.sep) + 1)
-  } else if (specifier.startsWith(pathe.dot.repeat(2))) {
-    specifier = specifier.slice(1)
-  } else if (specifier) {
-    specifier = pathe.dot + pathe.sep + specifier
+  let specifier: string
+
+  if (url.startsWith(parent) && parent.endsWith(pathe.sep)) {
+    // url is inside same directory as parent
+    specifier = pathe.dot + pathe.sep + url.slice(parent.length)
+  } else if (url === dirname || url.startsWith(dirname + pathe.sep)) {
+    // url is directory name of parent or inside same directory as parent
+    specifier = pathe.dot + pathe.sep + url.slice(dirname.length + 1)
   } else {
-    specifier = pathe.dot
+    // url is outside directory of parent
+    specifier = pathe.relative(parent, url)
+    ok(specifier.startsWith(pathe.dot), 'expected result to start with "."')
+
+    if (specifier !== pathe.dot && specifier !== pathe.dot.repeat(2)) {
+      if (/(?:\.\.\/){2,}/.test(specifier)) {
+        // remove first '../' segment:
+        // pathe.relative backs out of an extra directory
+        specifier = specifier.slice(specifier.indexOf(pathe.sep) + 1)
+      }
+    }
   }
 
   return specifier