fix: skip fragment check if website URL doesn't contain fragment

fixtures/fragments/file1.md

@@ -67,3 +67,33 @@ without related HTML element. Browser will scroll to the top of the page.
 A link to the non-existing fragment: [try](https://github.com/lycheeverse/lychee#non-existent-anchor).
 
 Skip the fragment check for directories like: [empty](empty_dir/).
+
+# Binary data URLs checks
+
+Fragment checking tries to scan the (whole) content/response body for HTML element IDs.
+This fails for binary data and can cause unnecessary traffic for remote URLs.
+
+## Without fragment
+
+Fragment checking is skipped if the URL does not actually contain a fragment.
+Even with fragment checking enabled, the following links must hence succeed:
+
+[Link to local binary file without fragment](zero.bin)
+[Link to local binary file with empty fragment](zero.bin#)
+[Link to remote binary file without fragment](https://raw.githubusercontent.com/lycheeverse/lychee/master/fixtures/fragments/zero.bin)
+[Link to remote binary file with empty fragment](https://raw.githubusercontent.com/lycheeverse/lychee/master/fixtures/fragments/zero.bin#)
+
+## Local file with fragment
+
+For local files URIs with fragment, the fragment checker is invoked and fails to read the content,
+but the file checker emits a warning only. The following link hence must succeed as well:
+
+[Link to local binary file with fragment](zero.bin#fragment)
+
+## Remote URL with fragment
+
+Right now, there is not MIME/content type based exclusion for fragment checks in the website checker.
+Also, other than the file checker, the website checker throws an error if reading the response body fails.
+The following link hence must fail:
+
+[Link to remote binary file with fragment](https://raw.githubusercontent.com/lycheeverse/lychee/master/fixtures/fragments/zero.bin#fragment)

fixtures/fragments/zero.bin

@@ -0,0 +1 @@
+âÔ

lychee-bin/tests/cli.rs

@@ -1876,10 +1876,22 @@ mod cli {
             .stderr(contains(
                 "https://github.com/lycheeverse/lychee#non-existent-anchor",
             ))
-            .stdout(contains("28 Total"))
-            .stdout(contains("23 OK"))
-            // 4 failures because of missing fragments
-            .stdout(contains("5 Errors"));
+            .stderr(contains("fixtures/fragments/zero.bin"))
+            .stderr(contains("fixtures/fragments/zero.bin#"))
+            .stderr(contains(
+                "https://raw.githubusercontent.com/MichaIng/lychee/skip-fragment-check-by-url/fixtures/fragments/zero.bin",
+            ))
+            .stderr(contains(
+                "https://raw.githubusercontent.com/MichaIng/lychee/skip-fragment-check-by-url/fixtures/fragments/zero.bin#",
+            ))
+            .stderr(contains("fixtures/fragments/zero.bin#fragment"))
+            .stderr(contains(
+                "https://raw.githubusercontent.com/MichaIng/lychee/skip-fragment-check-by-url/fixtures/fragments/zero.bin#fragment",
+            ))
+            .stdout(contains("34 Total"))
+            .stdout(contains("28 OK"))
+            // Failures because of missing fragments or failed binary body scan
+            .stdout(contains("6 Errors"));
     }
 
     #[test]

lychee-lib/src/checker/file.rs

@@ -125,7 +125,10 @@ impl FileChecker {
     async fn check_existing_path(&self, path: &Path, uri: &Uri) -> Status {
         // Only files can contain content with fragments.
         // Skip if the uri doesn't have the fragment.
-        if self.include_fragments && path.is_file() && uri.url.fragment().is_some() {
+        if self.include_fragments
+            && path.is_file()
+            && uri.url.fragment().is_some_and(|x| !x.is_empty())
+        {
             self.check_fragment(path, uri).await
         } else {
             Status::Ok(StatusCode::OK)

lychee-lib/src/checker/website.rs

@@ -103,7 +103,11 @@ impl WebsiteChecker {
         match self.reqwest_client.execute(request).await {
             Ok(response) => {
                 let status = Status::new(&response, &self.accepted);
-                if self.include_fragments && status.is_success() && method == Method::GET {
+                if self.include_fragments
+                    && status.is_success()
+                    && method == Method::GET
+                    && response.url().fragment().is_some_and(|x| !x.is_empty())
+                {
                     self.check_html_fragment(status, response).await
                 } else {
                     status