docs(semantic): add doc comments for SymbolTester and SemanticTester (#4433)

crates/oxc_semantic/src/builder.rs

@@ -147,6 +147,9 @@ impl<'a> SemanticBuilder<'a> {
         self
     }
 
+    /// Enable or disable building a [`ControlFlowGraph`].
+    ///
+    /// [`ControlFlowGraph`]: oxc_cfg::ControlFlowGraph
     #[must_use]
     pub fn with_cfg(mut self, cfg: bool) -> Self {
         self.cfg = if cfg { Some(ControlFlowGraphBuilder::default()) } else { None };

crates/oxc_semantic/tests/integration/symbols.rs

@@ -113,7 +113,7 @@ fn test_types_simple() {
         .has_some_symbol("T")
         .contains_flags(SymbolFlags::TypeParameter)
         .has_number_of_references(1)
-        .has_number_of_references_where(1, oxc_semantic::Reference::is_type)
+        .has_number_of_references_where(1, Reference::is_type)
         .test();
 
     SemanticTester::ts("function foo<T>(a: T): void {}")

crates/oxc_semantic/tests/integration/util/mod.rs

@@ -15,9 +15,15 @@ pub use symbol_tester::SymbolTester;
 
 #[must_use]
 pub struct SemanticTester<'a> {
+    /// Memory arena that AST and [`Semantic`] will store data in.
     allocator: Allocator,
+    /// Source type of the test case.
     source_type: SourceType,
+    /// The source text of the test case.
     source_text: &'a str,
+    /// Build a [`ControlFlowGraph`]?
+    ///
+    /// [`ControlFlowGraph`]: oxc_cfg::ControlFlowGraph
     cfg: bool,
     /// Expect semantic analysis to produce errors.
     ///
@@ -47,6 +53,10 @@ impl<'a> SemanticTester<'a> {
         Self::new(source_text, SourceType::default().with_module(true))
     }
 
+    /// Create a new tester for some source text.
+    ///
+    /// You may find one of the other factory methods, like
+    /// [`SemanticTester::ts`] or [`SemanticTester::js`], more convenient.
     pub fn new(source_text: &'a str, source_type: SourceType) -> Self {
         Self {
             allocator: Allocator::default(),
@@ -64,20 +74,27 @@ impl<'a> SemanticTester<'a> {
     }
 
     /// Mark the [`SourceType`] as JSX
+    ///
+    /// If the source is currently TypeScript, it will become TSX.
     pub fn with_jsx(mut self, yes: bool) -> Self {
         self.source_type = self.source_type.with_jsx(yes);
         self
     }
 
+    /// Mark the [`SourceType`] as an ESM module.
     pub fn with_module(mut self, yes: bool) -> Self {
         self.source_type = self.source_type.with_module(yes);
         self
     }
 
+    /// Enable or disable building a [`ControlFlowGraph`].
+    ///
+    /// [`ControlFlowGraph`]: oxc_cfg::ControlFlowGraph
     pub fn with_cfg(mut self, yes: bool) -> Self {
         self.cfg = yes;
         self
     }
+
     /// The program being tested is expected to produce errors during semantic analysis.
     ///
     /// By default, programs are expected to be error-free.
@@ -201,6 +218,16 @@ impl<'a> SemanticTester<'a> {
         ClassTester::has_class(self.build(), name)
     }
 
+    /// Check if semantic analysis produces an error matching `message`.
+    ///
+    /// Matching is done using `.contains()`.
+    ///
+    /// ## Fails
+    /// - If [`parsing`] produces errors
+    /// - If [`SemanticBuilder`] finishes without producing any errors.
+    /// - If [`SemanticBuilder`] finishes with errors, but none of them match `message`
+    ///
+    /// [`parsing`]: oxc_parser::Parser::parse
     pub fn has_error(&self, message: &str) {
         let SemanticBuilderReturn { errors, .. } = self.build_with_errors();
         assert!(

crates/oxc_semantic/tests/integration/util/symbol_tester.rs

@@ -6,6 +6,30 @@ use oxc_span::CompactStr;
 
 use super::{Expect, SemanticTester};
 
+/// Test a symbol in the [`Semantic`] analysis results.
+///
+/// To use this, chain together assertions about the symbol, such as
+/// [`SymbolTester::contains_flags`], [`SymbolTester::has_number_of_reads`],
+/// etc., then finish the chain off with a call to [`SymbolTester::test`].
+///
+/// You will never create this struct manually. Instead, use one of
+/// [`SemanticTester`]'s factories, such as [`SemanticTester::has_root_symbol`].
+///
+/// # Example
+/// ```
+/// use oxc_semantic::{SymbolFlags, Semantic};
+/// use super::SemanticTester;
+///
+/// #[test]
+/// fn my_test() {
+///   SemanticTester::js("let x = 0; let foo = (0, x++)")
+///     .has_some_symbol("x")                  // find a symbol named "x" at any scope
+///     .contains_flags(SymbolFlags::Variable) // check that it's a variable
+///     .has_number_of_reads(1)                // check read references
+///     .has_number_of_writes(1)               // check write references
+///     .test();                               // finish the test. Will panic if any assertions failed.
+/// }
+///```
 #[must_use]
 pub struct SymbolTester<'a> {
     parent: &'a SemanticTester<'a>,
@@ -131,18 +155,27 @@ impl<'a> SymbolTester<'a> {
         self
     }
 
+    /// Check that this symbol has a certain number of read [`Reference`]s
+    ///
+    /// References that are both read and write are counted.
     pub fn has_number_of_reads(self, ref_count: usize) -> Self {
         self.has_number_of_references_where(ref_count, Reference::is_read)
     }
 
+    /// Check that this symbol has a certain number of write [`Reference`]s.
+    ///
+    /// References that are both read and write are counted.
     pub fn has_number_of_writes(self, ref_count: usize) -> Self {
         self.has_number_of_references_where(ref_count, Reference::is_write)
     }
 
+    /// Check that this symbol has a certain number of [`Reference`]s of any kind.
     pub fn has_number_of_references(self, ref_count: usize) -> Self {
         self.has_number_of_references_where(ref_count, |_| true)
     }
 
+    /// Check that this symbol has a certain number of [`Reference`]s that meet
+    /// some criteria established by a predicate.
     pub fn has_number_of_references_where<F>(mut self, ref_count: usize, filter: F) -> Self
     where
         F: FnMut(&Reference) -> bool,
@@ -170,6 +203,12 @@ impl<'a> SymbolTester<'a> {
         self
     }
 
+    /// Check that this symbol is exported.
+    ///
+    /// Export status is checked using the symbol's [`SymbolFlags`], not by
+    /// checking the [`oxc_semantic::ModuleRecord`].
+    ///
+    /// For the inverse of this assertion, use [`SymbolTester::is_not_exported`].
     #[allow(clippy::wrong_self_convention)]
     pub fn is_exported(mut self) -> Self {
         self.test_result = match self.test_result {
@@ -188,6 +227,12 @@ impl<'a> SymbolTester<'a> {
         self
     }
 
+    /// Check that this symbol is not exported.
+    ///
+    /// Export status is checked using the symbol's [`SymbolFlags`], not by
+    /// checking the [`oxc_semantic::ModuleRecord`].
+    ///
+    /// For the inverse of this assertion, use [`SymbolTester::is_exported`].
     #[allow(clippy::wrong_self_convention)]
     pub fn is_not_exported(mut self) -> Self {
         self.test_result = match self.test_result {