Update to gracefully handle nonexistent relative paths (#691)

* Update Input::new to gracefully handle nonexistent relative paths
* Add test checking Input::new can handle real relative paths
* Add better pre-conditions to Input::new tests
* Add integration tests for handling relative paths in lychee-bin
* Update lychee-lib/src/types/input.rs

lychee-bin/tests/cli.rs

@@ -874,4 +874,43 @@ mod cli {
 
         Ok(())
     }
+
+    #[test]
+    fn test_handle_relative_paths_as_input() -> Result<()> {
+        let test_path = fixtures_path();
+        let mut cmd = main_command();
+
+        cmd.current_dir(&test_path)
+            .arg("--verbose")
+            .arg("--exclude")
+            .arg("example.*")
+            .arg("--")
+            .arg("./TEST_DUMP_EXCLUDE.txt")
+            .assert()
+            .success()
+            .stdout(contains("3 Total"))
+            .stdout(contains("3 Excluded"));
+
+        Ok(())
+    }
+
+    #[test]
+    fn test_handle_nonexistent_relative_paths_as_input() -> Result<()> {
+        let test_path = fixtures_path();
+        let mut cmd = main_command();
+
+        cmd.current_dir(&test_path)
+            .arg("--verbose")
+            .arg("--exclude")
+            .arg("example.*")
+            .arg("--")
+            .arg("./NOT-A-REAL-TEST-FIXTURE.md")
+            .assert()
+            .failure()
+            .stderr(contains(
+                "Cannot find local file ./NOT-A-REAL-TEST-FIXTURE.md",
+            ));
+
+        Ok(())
+    }
 }

lychee-lib/src/types/input.rs

@@ -147,6 +147,9 @@ impl Input {
                 let path = PathBuf::from(value);
                 if path.exists() {
                     InputSource::FsPath(path)
+                } else if path.is_relative() {
+                    // If the file does not exist and it is a relative path, exit immediately
+                    return Err(ErrorKind::FileNotFound(path));
                 } else {
                     // Invalid path; check if a valid URL can be constructed from the input
                     // by prefixing it with a `http://` scheme.
@@ -374,6 +377,42 @@ fn is_excluded_path(excluded_paths: &[PathBuf], path: &PathBuf) -> bool {
 mod tests {
     use super::*;
 
+    #[test]
+    fn test_input_handles_real_relative_paths() {
+        let test_file = "./Cargo.toml";
+        let path = Path::new(test_file);
+
+        assert!(path.exists());
+        assert!(path.is_relative());
+
+        let input = Input::new(test_file, None, false, None);
+        assert!(input.is_ok());
+        assert!(matches!(
+            input,
+            Ok(Input {
+                source: InputSource::FsPath(PathBuf { .. }),
+                file_type_hint: None,
+                excluded_paths: None
+            })
+        ));
+    }
+
+    #[test]
+    fn test_input_handles_nonexistent_relative_paths() {
+        let test_file = "./nonexistent/relative/path";
+        let path = Path::new(test_file);
+
+        assert!(!path.exists());
+        assert!(path.is_relative());
+
+        let input = Input::new(test_file, None, false, None);
+        assert!(input.is_err());
+        assert!(matches!(
+            input,
+            Err(ErrorKind::FileNotFound(PathBuf { .. }))
+        ));
+    }
+
     #[test]
     fn test_valid_extension() {
         assert!(valid_extension(Path::new("file.md")));