Define ParserError exception

To give client code more control about what exceptions it catches.

Author: seddonym

README.md

@@ -67,16 +67,16 @@ bundle = rustfluent.Bundle(
 
 #### Parameters
 
-| Name        | Type             | Description                                                                                                                                                      |
-|-------------|------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------|
-| `language`  | `str`            | [Unicode Language Identifier](https://unicode.org/reports/tr35/tr35.html#Unicode_language_identifier) for the language.                                          |
-| `ftl_files` | `list[str]`      | Full paths to the FTL files containing the translations. Entries in later files overwrite earlier ones.                                                          |
-| `strict`    | `bool`, optional | In strict mode, a `ValueError` will be raised if there are any errors in the file. In non-strict mode, invalid Fluent messages will be excluded from the Bundle. |
+| Name        | Type             | Description                                                                                                                                                              |
+|-------------|------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| `language`  | `str`            | [Unicode Language Identifier](https://unicode.org/reports/tr35/tr35.html#Unicode_language_identifier) for the language.                                                  |
+| `ftl_files` | `list[str]`      | Full paths to the FTL files containing the translations. Entries in later files overwrite earlier ones.                                                                  |
+| `strict`    | `bool`, optional | In strict mode, a `ParserError` will be raised if there are any errors in the file. In non-strict mode, invalid Fluent messages will be excluded from the Bundle. |
 
 #### Raises
 
 - `FileNotFoundError` if any of the FTL files could not be found.
-- `ValueError` if any of the FTL files contain errors (strict mode only).
+- `rustfluent.ParserError` if any of the FTL files contain errors (strict mode only).
 
 ### `Bundle.get_translation`
 

src/lib.rs

@@ -7,9 +7,14 @@ use pyo3::types::{PyDict, PyList};
 use std::fs;
 use unic_langid::LanguageIdentifier;
 
+use pyo3::create_exception;
+
+create_exception!(rustfluent, PyParserError, pyo3::exceptions::PyException);
+
 #[pymodule]
 fn rustfluent(m: &Bound<'_, PyModule>) -> PyResult<()> {
     m.add_class::<Bundle>()?;
+    m.add("ParserError", m.py().get_type_bound::<PyParserError>())?;
     Ok(())
 }
 
@@ -37,8 +42,9 @@ impl Bundle {
                 Ok(resource) => resource,
                 Err(error) => {
                     if strict {
-                        return Err(PyValueError::new_err(format!(
-                            "{error:?} - Fluent file contains errors"
+                        return Err(PyParserError::new_err(format!(
+                            "Error when parsing {}.",
+                            file_path
                         )));
                     } else {
                         // The first element of the error is the parsed resource, minus any

tests/test_python_interface.py

@@ -1,6 +1,6 @@
 #!/usr/bin/env python
-
 import pathlib
+import re
 
 import pytest
 
@@ -78,6 +78,7 @@ def test_parses_other_parts_of_file_that_contains_errors_in_non_strict_mode(
     assert translation == "I'm valid."
 
 
-def test_raises_value_error_on_file_that_contains_errors_in_strict_mode():
-    with pytest.raises(ValueError):
-        fluent.Bundle("fr", [str(data_dir / "errors.ftl")], strict=True)
+def test_raises_parser_error_on_file_that_contains_errors_in_strict_mode():
+    filename = str(data_dir / "errors.ftl")
+    with pytest.raises(fluent.ParserError, match=re.escape(f"Error when parsing {filename}.")):
+        fluent.Bundle("fr", [filename], strict=True)