fix: only try to load external files with relative paths

Author: kaisermann

Diff for: README.md

@@ -74,6 +74,8 @@ _Vue-like_ support for defining your markup between a specific tag. The default
 <style src="./style.css"></style>
 ```
 
+> Note: using a relative path starting with `.` is important. Otherwise `svelte-preprocess` will ignore the `src` attribute.
+
 ### Global style
 
 #### `global` attribute

Diff for: src/modules/utils.ts

@@ -60,15 +60,8 @@ export async function hasDepInstalled(dep: string) {
   return (depCheckCache[dep] = result);
 }
 
-const REMOTE_SRC_PATTERN = /^(https?:)?\/\//;
-
 export function isValidLocalPath(path: string) {
-  return (
-    path.match(REMOTE_SRC_PATTERN) == null &&
-    // only literal strings allowed
-    !path.startsWith('{') &&
-    !path.endsWith('}')
-  );
+  return path.startsWith('.') && !path.startsWith('{') && !path.endsWith('}');
 }
 
 // finds a existing path up the tree

Diff for: test/autoProcess/externalFiles.test.ts

@@ -68,23 +68,40 @@ describe('external files', () => {
     expect(markup.code).toContain(getFixtureContent('template.html'));
   });
 
+  it("warns if local file don't exist", async () => {
+    const input = `<style src="./missing-potato"></style>`;
+
+    await preprocess(input, sveltePreprocess());
+
+    expect(warnSpy).toHaveBeenCalledWith(
+      expect.stringContaining('was not found'),
+    );
+  });
+
   REMOTE_JS.forEach((url) => {
-    it(`should not attempt to locally resolve ${url}`, async () => {
+    it(`ignores remote path "${url}"`, async () => {
       const input = `<div></div><script src="${url}"></script>`;
 
       const preprocessed = await preprocess(input, sveltePreprocess());
 
       expect(preprocessed.toString?.()).toContain(input);
       expect(preprocessed.dependencies).toHaveLength(0);
+      expect(warnSpy).not.toHaveBeenCalledWith(
+        expect.stringContaining('was not found'),
+      );
     });
   });
 
-  it("should warn if local file don't exist", async () => {
-    const input = `<style src="./missing-potato"></style>`;
+  it('ignores external source if path is not relative', async () => {
+    const input = `<style src="/root-potato"></style>`;
 
     await preprocess(input, sveltePreprocess());
 
-    expect(warnSpy).toHaveBeenCalledWith(
+    const preprocessed = await preprocess(input, sveltePreprocess());
+
+    expect(preprocessed.toString?.()).toContain(input);
+    expect(preprocessed.dependencies).toHaveLength(0);
+    expect(warnSpy).not.toHaveBeenCalledWith(
       expect.stringContaining('was not found'),
     );
   });