fix(visitor): apply tagged template handling

packages/swc-coverage-instrument/src/macros/create_instrumentation_visitor.rs

@@ -190,5 +190,6 @@ macro_rules! create_instrumentation_visitor {
  on_enter!(AssignPat);
  on_enter!(GetterProp);
  on_enter!(SetterProp);
+ on_enter!(TaggedTpl);
  }
 }

packages/swc-coverage-instrument/src/macros/instrumentation_counter_helper.rs

@@ -236,6 +236,18 @@ macro_rules! instrumentation_counter_helper {
  }
 
  fn cover_statement(&mut self, expr: &mut Expr) {
+ // Special handling for tagged template expressions (like emotion styled components)
+ // to preserve the template relationship and avoid wrapping in sequence expressions
+ if let Expr::TaggedTpl(_) = expr {
+ // For tagged templates, prepend statement counter instead of wrapping
+ // This preserves the template relationship
+ let span = expr.span();
+ self.mark_prepend_stmt_counter(&span);
+ // Still visit children to instrument any inner expressions
+ expr.visit_mut_children_with(self);
+ return;
+ }
+
  let span = expr.span();
  // This is ugly, poor man's substitute to istanbul's `insertCounter` to determine
  // when to replace givn expr to wrapped Paren or prepend stmt counter.

packages/swc-coverage-instrument/src/macros/instrumentation_visitor.rs

@@ -267,6 +267,31 @@ macro_rules! instrumentation_visitor {
  self.on_exit(old);
  }
 
+ // TaggedTemplateExpression: special handling to preserve template relationship
+ #[tracing::instrument(skip_all, fields(node = %self.print_node()))]
+ fn visit_mut_tagged_tpl(&mut self, tagged_tpl: &mut TaggedTpl) {
+ let (old, ignore_current) = self.on_enter(tagged_tpl);
+
+ match ignore_current {
+ Some(crate::hint_comments::IgnoreScope::Next) => {}
+ _ => {
+ // For tagged template expressions like styled(...)`template`,
+ // we need to instrument the entire expression rather than wrapping
+ // the tag part in a sequence expression, which would break the
+ // template relationship and cause emotion to lose label information.
+
+ // Instead of calling cover_statement on the tag (which would wrap it),
+ // we mark to prepend a statement counter before the entire tagged template
+ self.mark_prepend_stmt_counter(&tagged_tpl.span);
+
+ // Visit children normally to instrument any inner expressions
+ tagged_tpl.visit_mut_children_with(self);
+ }
+ }
+
+ self.on_exit(old);
+ }
+
  // ReturnStatement: entries(coverStatement),
  #[tracing::instrument(skip_all, fields(node = %self.print_node()))]
  fn visit_mut_return_stmt(&mut self, return_stmt: &mut ReturnStmt) {

packages/swc-coverage-instrument/src/utils/node.rs

@@ -44,6 +44,7 @@ pub enum Node {
  ExportDefaultDecl,
  BlockStmt,
  AssignPat,
+ TaggedTpl,
 }
 
 impl Display for Node {

spec/plugin.spec.ts

@@ -28,4 +28,83 @@ ${code}
 `,
  );
  });
+
+ it("should preserve emotion styled component labels with template literals", () => {
+ // This reproduces the issue from GitHub #247
+ // Input: code AFTER emotion processing (as shown in the GitHub issue)
+ const code = `export var TabsList = /*#__PURE__*/ styled(TabsListCore, {
+ target: "ebt2y835",
+ label: "TabsList"
+})("margin:0 auto;width:fit-content;");`;
+
+ const output = instrumentSync(code, "test-emotion.js");
+
+ // Expected output: should preserve label like v0.0.20 did (from GitHub issue)
+ // The key difference: label should remain "TabsList", not become ""
+ const expectedOutput = `"use strict";
+Object.defineProperty(exports, "__esModule", {
+ value: true
+});
+Object.defineProperty(exports, "TabsList", {
+ enumerable: true,
+ get: function() {
+ return TabsList;
+ }
+});
+var TabsList = (cov_14220330533750098279().s[0]++, /*#__PURE__*/ styled(TabsListCore, {
+ target: "ebt2y835",
+ label: "TabsList"
+})("margin:0 auto;width:fit-content;")); /*__coverage_data_json_comment__::{"all":false,"path":"test-emotion.js","statementMap":{"0":{"start":{"line":1,"column":36},"end":{"line":4,"column":38}}},"fnMap":{},"branchMap":{},"s":{"0":0},"f":{},"b":{}}*/ 
+function cov_14220330533750098279() {
+ var path = "test-emotion.js";
+ var hash = "15339889637910252771";
+ var global = new ((function(){}).constructor)("return this")();
+ var gcv = "__coverage__";
+ var coverageData = {
+ all: false,
+ path: "test-emotion.js",
+ statementMap: {
+ "0": {
+ start: {
+ line: 1,
+ column: 36
+ },
+ end: {
+ line: 4,
+ column: 38
+ }
+ }
+ },
+ fnMap: {},
+ branchMap: {},
+ s: {
+ "0": 0
+ },
+ f: {},
+ b: {},
+ _coverageSchema: "11020577277169172593",
+ hash: "15339889637910252771"
+ };
+ var coverage = global[gcv] || (global[gcv] = {});
+ if (!coverage[path] || coverage[path].$hash !== hash) {
+ coverage[path] = coverageData;
+ }
+ var actualCoverage = coverage[path];
+ {
+ cov_14220330533750098279 = function() {
+ return actualCoverage;
+ };
+ }
+ return actualCoverage;
+}
+cov_14220330533750098279();`;
+
+ // Compare whole output.code to the raw output as requested
+ // This ensures emotion labels are preserved without explicitly asserting them
+ assert.equal(
+ output.code.trim(),
+ expectedOutput.trim(),
+ "Instrumented code should preserve emotion styled component label property",
+ );
+ });
 });