fix: lower length of key to improve usage in win32

CHANGELOG.md

@@ -4,6 +4,8 @@
 
 ### Fixes
 
+- getCacheKey reduces size of global cache key portion to 16 characters.  ([#13826](https://github.com/facebook/jest/pull/13827))
+
 ### Chore & Maintenance
 
 ### Performance

packages/jest-create-cache-key-function/src/index.ts

@@ -40,7 +40,19 @@ type NewGetCacheKeyFunction = (
 
 type GetCacheKeyFunction = OldGetCacheKeyFunction | NewGetCacheKeyFunction;
 
-function getGlobalCacheKey(files: Array<string>, values: Array<string>) {
+/**
+ * Computes the global cache key given  a collection of files and values.  This limits
+ * the output with a provided length.
+ * @param files list of files to read
+ * @param values list of values to add to the computation
+ * @param length length of the resulting key
+ * @returns {string} the global cache key
+ */
+function getGlobalCacheKey(
+  files: Array<string>,
+  values: Array<string>,
+  length: number,
+) {
   return [
     process.env.NODE_ENV,
     process.env.BABEL_ENV,
@@ -52,7 +64,7 @@ function getGlobalCacheKey(files: Array<string>, values: Array<string>) {
       createHash('sha1'),
     )
     .digest('hex')
-    .substring(0, 32);
+    .substring(0, length);
 }
 
 function getCacheKeyFunction(globalCacheKey: string): GetCacheKeyFunction {
@@ -75,9 +87,18 @@ function getCacheKeyFunction(globalCacheKey: string): GetCacheKeyFunction {
   };
 }
 
+/**
+ * Computes the cache key given  a collection of files and values.  This limits
+ * the output with a provided length.
+ * @param files list of files to read
+ * @param values list of values to add to the computation
+ * @param length length of the resulting key defaults to 16
+ * @returns {string} the global cache key
+ */
 export default function createCacheKey(
   files: Array<string> = [],
   values: Array<string> = [],
+  length = 16,
 ): GetCacheKeyFunction {
-  return getCacheKeyFunction(getGlobalCacheKey(files, values));
+  return getCacheKeyFunction(getGlobalCacheKey(files, values, length));
 }