Support specifying baseline in configuration file (#2137)

Summary:
Adds support for setting the baseline file path in `pyrefly.toml` or `pyproject.toml`, so users don't need to pass `--baseline` on every invocation.
```toml
  # pyrefly.toml
  baseline = "baseline.json"
```
- Add baseline field to ConfigFile struct
- Read baseline from config when CLI flag not provided
- CLI --baseline takes precedence over config
- Update documentation

Fixes #2119

Pull Request resolved: #2137

Test Plan:
- Added unit test for parsing baseline from config
- Updated test_rewrite_with_path_to_config to include baseline path
- Ran python3 test.py -> all tests pass
- Manual testing: verified baseline works from config, CLI override works

Reviewed By: yangdanny97

Differential Revision: D90895437

Pulled By: grievejia

fbshipit-source-id: 1117c281fbbf4ba9c96c53bddaa2e12e64e7bce5

Author: AryanBagade

crates/pyrefly_config/src/config.rs

@@ -465,6 +465,11 @@ pub struct ConfigFile {
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub typeshed_path: Option<PathBuf>,
 
+    /// Path to baseline file for comparing type errors.
+    /// Errors matching the baseline are suppressed.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub baseline: Option<PathBuf>,
+
     /// Pyrefly's configurations around interpreter querying/finding.
     #[serde(flatten)]
     pub interpreters: Interpreters,
@@ -542,6 +547,7 @@ impl Default for ConfigFile {
             source_db: Default::default(),
             use_ignore_files: true,
             typeshed_path: None,
+            baseline: None,
             skip_lsp_config_indexing: false,
         }
     }
@@ -1176,6 +1182,9 @@ impl ConfigFile {
         if let Some(typeshed_path) = &self.typeshed_path {
             self.typeshed_path = Some(typeshed_path.absolutize_from(config_root));
         }
+        if let Some(baseline) = &self.baseline {
+            self.baseline = Some(baseline.absolutize_from(config_root));
+        }
         self.python_environment
             .site_package_path
             .iter_mut()
@@ -1441,6 +1450,7 @@ mod tests {
                     }
                 }],
                 typeshed_path: None,
+                baseline: None,
                 skip_lsp_config_indexing: false,
             }
         );
@@ -1673,6 +1683,7 @@ mod tests {
                 settings: Default::default(),
             }],
             typeshed_path: Some(PathBuf::from(typeshed)),
+            baseline: Some(PathBuf::from("baseline.json")),
             skip_lsp_config_indexing: false,
         };
 
@@ -1731,6 +1742,7 @@ mod tests {
                 settings: Default::default(),
             }],
             typeshed_path: Some(expected_typeshed),
+            baseline: Some(test_path.join("baseline.json")),
             skip_lsp_config_indexing: false,
         };
         assert_eq!(config, expected_config);
@@ -1758,6 +1770,15 @@ mod tests {
         assert!(err.to_string().contains("missing field `matches`"));
     }
 
+    #[test]
+    fn test_baseline_config_parsing() {
+        let config_str = r#"
+baseline = "baseline.json"
+"#;
+        let config = ConfigFile::parse_config(config_str).unwrap();
+        assert_eq!(config.baseline, Some(PathBuf::from("baseline.json")));
+    }
+
     #[test]
     fn test_expect_all_fields_set_in_root_config() {
         let root = TempDir::new().unwrap();

pyrefly/lib/commands/check.rs

@@ -650,7 +650,7 @@ impl Timings {
 
 impl CheckArgs {
     pub fn run_once(
-        self,
+        mut self,
         files_to_check: Box<dyn Includes>,
         config_finder: ConfigFinder,
     ) -> anyhow::Result<(CommandExitStatus, Vec<Error>)> {
@@ -677,6 +677,18 @@ impl CheckArgs {
             true,
         );
         let (loaded_handles, _, sourcedb_errors) = handles.all(holder.as_ref().config_finder());
+
+        // If CLI doesn't provide baseline, get from config
+        if self.output.baseline.is_none()
+            && let Some(handle) = loaded_handles.first()
+        {
+            let config = holder.as_ref().config_finder().python_file(
+                ModuleNameWithKind::guaranteed(handle.module()),
+                handle.path(),
+            );
+            self.output.baseline = config.baseline.clone();
+        }
+
         self.run_inner(
             timings,
             transaction.as_mut(),
@@ -687,7 +699,7 @@ impl CheckArgs {
     }
 
     pub fn run_once_with_snippet(
-        self,
+        mut self,
         code: String,
         config_finder: ConfigFinder,
     ) -> anyhow::Result<(CommandExitStatus, Vec<Error>)> {
@@ -699,13 +711,18 @@ impl CheckArgs {
         let holder = Forgetter::new(State::new(config_finder), true);
 
         // Create a single handle for the virtual module
-        let sys_info = holder
+        let config = holder
             .as_ref()
             .config_finder()
-            .python_file(ModuleNameWithKind::guaranteed(module_name), &module_path)
-            .get_sys_info();
+            .python_file(ModuleNameWithKind::guaranteed(module_name), &module_path);
+        let sys_info = config.get_sys_info();
         let handle = Handle::new(module_name, module_path.clone(), sys_info);
 
+        // If CLI doesn't provide baseline, get from config
+        if self.output.baseline.is_none() {
+            self.output.baseline = config.baseline.clone();
+        }
+
         let require_levels = self.get_required_levels();
         let mut transaction = Forgetter::new(
             holder
@@ -730,7 +747,7 @@ impl CheckArgs {
     }
 
     pub async fn run_watch(
-        self,
+        mut self,
         mut watcher: Watcher,
         files_to_check: Box<dyn Includes>,
         config_finder: ConfigFinder,
@@ -741,6 +758,19 @@ impl CheckArgs {
         let require_levels = self.get_required_levels();
         let mut handles = Handles::new(expanded_file_list);
         let state = State::new(config_finder);
+
+        // If CLI doesn't provide baseline, get from config
+        if self.output.baseline.is_none() {
+            let (loaded_handles, _, _) = handles.all(state.config_finder());
+            if let Some(handle) = loaded_handles.first() {
+                let config = state.config_finder().python_file(
+                    ModuleNameWithKind::guaranteed(handle.module()),
+                    handle.path(),
+                );
+                self.output.baseline = config.baseline.clone();
+            }
+        }
+
         let mut transaction = state.new_committable_transaction(require_levels.default, None);
         loop {
             let timings = Timings::new();

website/docs/error-suppressions.mdx

@@ -86,14 +86,29 @@ To generate (or re-generate) the baseline file:
 pyrefly check --baseline="<path to baseline file>" --update-baseline
 ```
 
-To check your project using a baseline file and report only newly-introduced errors:
+To check your project using a baseline file and report only newly-introduced errors, you can either use the CLI flag:
 
 ```
 pyrefly check --baseline="<path to baseline file>"
 ```
 
+Or specify the baseline in your configuration file (`pyrefly.toml` or `pyproject.toml`):
+
+```toml
+# pyrefly.toml
+baseline = "baseline.json"
+```
+
+```toml
+# pyproject.toml
+[tool.pyrefly]
+baseline = "baseline.json"
+```
+
+When the baseline is specified in the configuration file, you don't need to pass the `--baseline` flag on every invocation. The CLI flag takes precedence if both are specified.
+
 Errors are matched with the baseline by looking at file, error code, and column number.
-Right now, errors suppressed by the baseline file are still shown in the IDE and the baseline file can only be passed as a command line argument, but both are expected to change in the future.
+Note that errors suppressed by the baseline file are still shown in the IDE.
 This feature is experimental, so please submit any feedback or requests you have on our Github repo.
 
 ## Upgrading Pyrefly (And other changes that introduce new type errors)