Add the file reference on a YAML error message

I had a process get killed half-way through writing a pending snapshot and it was difficult to debug what was going on, especially since in PRQL we gitignore pending snapshots.

Not sure this is the best way — very open to feedback; in retrospect it seems somewhat verbose to add a simple reference in an error message.

src/content/mod.rs

@@ -20,7 +20,7 @@ use std::fmt;
 /// An internal error type for content related errors.
 #[derive(Debug)]
 pub enum Error {
-    FailedParsingYaml,
+    FailedParsingYaml(Option<std::path::PathBuf>),
     UnexpectedDataType,
     #[cfg(feature = "_cargo_insta_internal")]
     MissingField,
@@ -29,7 +29,10 @@ pub enum Error {
 impl fmt::Display for Error {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
-            Self::FailedParsingYaml => f.write_str("Failed parsing the provided YAML text"),
+            Self::FailedParsingYaml(None) => f.write_str("Failed parsing the provided YAML text"),
+            Self::FailedParsingYaml(Some(pathbuf)) => f.write_str(
+                format!("Failed parsing the YAML from {:?}", pathbuf.as_os_str()).as_str(),
+            ),
             Self::UnexpectedDataType => {
                 f.write_str("The present data type wasn't what was expected")
             }

src/content/yaml.rs

@@ -4,11 +4,11 @@ use yaml_rust::{yaml::Hash as YamlObj, Yaml as YamlValue};
 
 pub fn parse_str(s: &str) -> Result<Content, Error> {
     let mut blobs =
-        yaml_rust::YamlLoader::load_from_str(s).map_err(|_| Error::FailedParsingYaml)?;
+        yaml_rust::YamlLoader::load_from_str(s).map_err(|_| Error::FailedParsingYaml(None))?;
 
     match (blobs.pop(), blobs.pop()) {
         (Some(blob), None) => from_yaml_blob(blob).map_err(Into::into),
-        _ => Err(Error::FailedParsingYaml),
+        _ => Err(Error::FailedParsingYaml(None)),
     }
 }
 
@@ -36,7 +36,7 @@ fn from_yaml_blob(blob: YamlValue) -> Result<Content, Error> {
                 .collect::<Result<_, Error>>()?;
             Ok(Content::Map(obj))
         }
-        YamlValue::BadValue | YamlValue::Alias(_) => Err(Error::FailedParsingYaml),
+        YamlValue::BadValue | YamlValue::Alias(_) => Err(Error::FailedParsingYaml(None)),
     }
 }
 

src/snapshot.rs

@@ -286,7 +286,14 @@ impl Snapshot {
                     break;
                 }
             }
-            let content = yaml::parse_str(&buf)?;
+            let content = yaml::parse_str(&buf).map_err(|e| {
+                // Add file context to error
+                if matches!(e, content::Error::FailedParsingYaml(None)) {
+                    content::Error::FailedParsingYaml(Some(p.to_path_buf()))
+                } else {
+                    e
+                }
+            })?;
             MetaData::from_content(content)?
         // legacy format
         } else {
@@ -878,3 +885,24 @@ fn test_inline_snapshot_value_newline() {
     // https://github.com/mitsuhiko/insta/issues/39
     assert_eq!(get_inline_snapshot_value("\n"), "");
 }
+
+#[test]
+fn test_parse_yaml_error() {
+    use std::env::temp_dir;
+    let mut temp = temp_dir();
+    temp.push("bad.yaml");
+    let mut f = fs::File::create(temp.clone()).unwrap();
+
+    let invalid = r#"---
+    This is invalid yaml:
+     {
+        {
+    ---
+    "#;
+
+    f.write_all(invalid.as_bytes()).unwrap();
+
+    let error = format!("{}", Snapshot::from_file(temp.as_path()).unwrap_err());
+    assert!(error.contains("Failed parsing the YAML from"));
+    assert!(error.contains("/bad.yaml"));
+}