Cache instances of SourceMapConsumer

Creating these was apparently a little expensive.

This fixes #1256 [1].

[1] #1256

CHANGELOG.md

@@ -6,6 +6,8 @@ All notable changes to this project will be documented in this file.
 
 - Correctly represent consecutive BeforeAll & AfterAll hooks in the command log, relates to [#1250](https://github.com/badeball/cypress-cucumber-preprocessor/issues/1250).
 
+- Cache instances of SourceMapConsumer, fixes [#1256](https://github.com/badeball/cypress-cucumber-preprocessor/issues/1256).
+
 ## v21.0.2
 
 - Cache requested source maps, fixes [#1245](https://github.com/badeball/cypress-cucumber-preprocessor/discussions/1245).

lib/helpers/source-map.ts

@@ -21,7 +21,7 @@ function sourceMapWarn(message: string) {
   isSourceMapWarned = true;
 }
 
-const cache = new Map<string, string | undefined>();
+const cache = new Map<string, SourceMapConsumer | undefined>();
 
 /**
  * Taken from https://github.com/evanw/node-source-map-support/blob/v0.5.21/source-map-support.js#L148-L177.
@@ -63,11 +63,36 @@ export function retrieveSourceMapURL(source: string) {
   return lastMatch[1];
 }
 
-export function cachedRetrieveSourceMapURL(source: string): string | undefined {
+export function createSourceMapConsumer(
+  source: string,
+): SourceMapConsumer | undefined {
+  const sourceMappingURL = retrieveSourceMapURL(source);
+
+  if (!sourceMappingURL) {
+    return;
+  }
+
+  const rawSourceMap = JSON.parse(
+    new TextDecoder().decode(
+      toByteArray(sourceMappingURL.slice(sourceMappingURL.indexOf(",") + 1)),
+    ),
+  );
+
+  // Why? Because of Vite. Vite fails building the source-map module properly and this errors with "x is not a constructor".
+  if (typeof SourceMapConsumer !== "function") {
+    return;
+  }
+
+  return new SourceMapConsumer(rawSourceMap);
+}
+
+export function cachedCreateSourceMapConsumer(
+  source: string,
+): SourceMapConsumer | undefined {
   if (cache.has(source)) {
     return cache.get(source);
   } else {
-    const result = retrieveSourceMapURL(source);
+    const result = createSourceMapConsumer(source);
     cache.set(source, result);
     return result;
   }
@@ -80,25 +105,12 @@ export function maybeRetrievePositionFromSourceMap(): Position | undefined {
     return;
   }
 
-  const sourceMappingURL = cachedRetrieveSourceMapURL(stack[0].fileName);
+  const sourceMap = cachedCreateSourceMapConsumer(stack[0].fileName);
 
-  if (!sourceMappingURL) {
+  if (!sourceMap) {
     return;
   }
 
-  const rawSourceMap = JSON.parse(
-    new TextDecoder().decode(
-      toByteArray(sourceMappingURL.slice(sourceMappingURL.indexOf(",") + 1)),
-    ),
-  );
-
-  // Why? Because of Vite. Vite fails building the source-map module properly and this errors with "x is not a constructor".
-  if (typeof SourceMapConsumer !== "function") {
-    return;
-  }
-
-  const sourceMap = new SourceMapConsumer(rawSourceMap);
-
   const relevantFrame = stack[3];
 
   const position = sourceMap.originalPositionFor({