feat(next/swc): support experimental coverage instrument

Author: kwonoj

packages/next-swc/Cargo.lock

@@ -28,6 +28,7 @@ swc_ecma_loader = { version = "0.29.1", features = ["node", "lru"] }
 swc_ecmascript = { version = "0.150.0", features = ["codegen", "minifier", "optimization", "parser", "react", "transforms", "typescript", "utils", "visit"] }
 swc_cached = "0.1.1"
 tracing = { version = "0.1.32", features = ["release_max_level_info"] }
+swc-coverage-instrument = "0.0.2"
 
 [dev-dependencies]
 swc_ecma_transforms_testing = "0.82.0"

packages/next-swc/crates/core/Cargo.toml

@@ -43,7 +43,7 @@ use swc_common::{FileName, SourceFile, SourceMap};
 use swc_ecmascript::ast::EsVersion;
 use swc_ecmascript::parser::parse_file_as_module;
 use swc_ecmascript::transforms::pass::noop;
-use swc_ecmascript::visit::Fold;
+use swc_ecmascript::visit::{as_folder, Fold};
 
 pub mod amp_attributes;
 mod auto_cjs;
@@ -104,9 +104,12 @@ pub struct TransformOptions {
 
     #[serde(default)]
     pub modularize_imports: Option<modularize_imports::Config>,
+
+    #[serde(default)]
+    pub coverage_instrument: Option<swc_coverage_instrument::InstrumentOptions>,
 }
 
-pub fn custom_before_pass<'a, C: Comments + 'a>(
+pub fn custom_before_pass<'a, C: Comments + 'a + std::clone::Clone>(
     cm: Arc<SourceMap>,
     file: Arc<SourceFile>,
     opts: &'a TransformOptions,
@@ -193,8 +196,8 @@ pub fn custom_before_pass<'a, C: Comments + 'a>(
                         Either::Left(swc_emotion::EmotionTransformer::new(
                             config.clone(),
                             path,
-                            cm,
-                            comments,
+                            cm.clone(),
+                            comments.clone(),
                         ))
                     })
                 } else {
@@ -205,7 +208,18 @@ pub fn custom_before_pass<'a, C: Comments + 'a>(
         match &opts.modularize_imports {
             Some(config) => Either::Left(modularize_imports::modularize_imports(config.clone())),
             None => Either::Right(noop()),
-        }
+        },
+        match &opts.coverage_instrument {
+            Some(config) => Either::Left(as_folder(
+                swc_coverage_instrument::create_coverage_instrumentation_visitor(
+                    cm,
+                    comments,
+                    config.clone(),
+                    file.name.to_string()
+                )
+            )),
+            None => Either::Right(noop()),
+        },
     )
 }
 

packages/next-swc/crates/core/src/lib.rs

@@ -10,6 +10,7 @@ use next_swc::{
 };
 use std::path::PathBuf;
 use swc_common::{chain, comments::SingleThreadedComments, FileName, Mark};
+use swc_coverage_instrument::create_coverage_instrumentation_visitor;
 use swc_ecma_transforms_testing::{test, test_fixture};
 use swc_ecmascript::{
     parser::{EsConfig, Syntax},
@@ -209,3 +210,21 @@ fn shake_exports_fixture_default(input: PathBuf) {
         &output,
     );
 }
+
+#[fixture("tests/fixture/coverage-instrument/input.js")]
+fn coverage_instrument_simple_default(input: PathBuf) {
+    let output = input.parent().unwrap().join("output.js");
+    test_fixture(
+        syntax(),
+        &|tr| {
+            swc_ecmascript::visit::as_folder(create_coverage_instrumentation_visitor(
+                tr.cm.clone(),
+                tr.comments.clone(),
+                Default::default(),
+                "anon".to_string(),
+            ))
+        },
+        &input,
+        &output,
+    );
+}

packages/next-swc/crates/core/tests/fixture.rs

@@ -0,0 +1,6 @@
+function* x() { yield 1; yield 2; };
+var k;
+output = 0;
+for (k of x()) {
+  output += k;
+}

packages/next-swc/crates/core/tests/fixture/coverage-instrument/input.js

@@ -0,0 +1,130 @@
+function cov_473891610594984201() {
+    var path = "anon";
+    var hash = "13293363232410732979";
+    var global = new Function("return this")();
+    var gcv = "__coverage__";
+    var coverageData = {
+        all: false,
+        path: "anon",
+        statementMap: {
+            "0": {
+                start: {
+                    line: 1,
+                    column: 16
+                },
+                end: {
+                    line: 1,
+                    column: 24
+                }
+            },
+            "1": {
+                start: {
+                    line: 1,
+                    column: 25
+                },
+                end: {
+                    line: 1,
+                    column: 33
+                }
+            },
+            "2": {
+                start: {
+                    line: 3,
+                    column: 0
+                },
+                end: {
+                    line: 3,
+                    column: 11
+                }
+            },
+            "3": {
+                start: {
+                    line: 4,
+                    column: 0
+                },
+                end: {
+                    line: 6,
+                    column: 1
+                }
+            },
+            "4": {
+                start: {
+                    line: 5,
+                    column: 2
+                },
+                end: {
+                    line: 5,
+                    column: 14
+                }
+            }
+        },
+        fnMap: {
+            "0": {
+                name: "x",
+                decl: {
+                    start: {
+                        line: 1,
+                        column: 10
+                    },
+                    end: {
+                        line: 1,
+                        column: 11
+                    }
+                },
+                loc: {
+                    start: {
+                        line: 1,
+                        column: 14
+                    },
+                    end: {
+                        line: 1,
+                        column: 35
+                    }
+                },
+                line: 1
+            }
+        },
+        branchMap: {},
+        s: {
+            "0": 0,
+            "1": 0,
+            "2": 0,
+            "3": 0,
+            "4": 0
+        },
+        f: {
+            "0": 0
+        },
+        b: {},
+        _coverageSchema: "11020577277169172593",
+        hash: "13293363232410732979"
+    };
+    var coverage = global[gcv] || (global[gcv] = {});
+    if (!coverage[path] || coverage[path].hash !== hash) {
+        coverage[path] = coverageData;
+    }
+    var actualCoverage = coverage[path];
+    {
+        cov_473891610594984201 = function() {
+            return actualCoverage;
+        };
+    }
+    return actualCoverage;
+}
+cov_473891610594984201();
+function* x() {
+    cov_473891610594984201().f[0]++;
+    cov_473891610594984201().s[0]++;
+    yield 1;
+    cov_473891610594984201().s[1]++;
+    yield 2;
+}
+;
+var k;
+cov_473891610594984201().s[2]++;
+output = 0;
+cov_473891610594984201().s[3]++;
+for (k of x()){
+    cov_473891610594984201().s[4]++;
+    output += k;
+}

packages/next-swc/crates/core/tests/fixture/coverage-instrument/output.js

@@ -63,6 +63,7 @@ fn test(input: &Path, minify: bool) {
                 shake_exports: None,
                 emotion: Some(assert_json("{}")),
                 modularize_imports: None,
+                coverage_instrument: None,
             };
 
             let options = options.patch(&fm);

packages/next-swc/crates/core/tests/full.rs

@@ -109,6 +109,7 @@ function getBaseSWCOptions({
     modularizeImports: nextConfig?.experimental?.modularizeImports,
     relay: nextConfig?.compiler?.relay,
     emotion: getEmotionOptions(nextConfig, development),
+    coverageInstrument: getCoverageInstrumentOptions(nextConfig),
   }
 }
 
@@ -139,6 +140,15 @@ function getEmotionOptions(nextConfig, development) {
   }
 }
 
+function getCoverageInstrumentOptions(nextConfig) {
+  const options = nextConfig?.experimental?.swcInstrumentCoverage
+  if (!options) {
+    return
+  }
+
+  return options === true ? {} : options
+}
+
 export function getJestSWCOptions({
   isServer,
   filename,

packages/next/build/swc/options.js

@@ -133,6 +133,14 @@ export interface ExperimentalConfig {
     }
   >
   swcTraceProfiling?: boolean
+  swcInstrumentCoverage?:
+    | boolean
+    | {
+        coverageVariable?: string
+        compact?: boolean
+        reportLogic?: boolean
+        ignoreClassMethods?: Array<string>
+      }
 }
 
 /**