feat: default cacheDirectory to TEST_TMPDIR (#231)

* feat: default cacheDirectory to TEST_TMPDIR

See #230

* use dedicated jest cache folder under TEST_TMPDIR

e2e/case13.sh

@@ -0,0 +1,25 @@
+#!/usr/bin/env bash
+set -o errexit -o nounset -o pipefail
+
+# Jest default is os.tmpdir()/jest_<uid>
+TEST_TMPDIR=$(mktemp -d)/jest_test_tmpdir
+
+# Case 13: jest_test uses TEST_TMPDIR
+rm -rf "$TEST_TMPDIR"
+bazel test //jest/tests:case13 --nocache_test_results --test_tmpdir=$TEST_TMPDIR
+
+# Locate the cache folder under TEST_TMPDIR
+JEST_CACHE_NAME="jest_cache"
+JEST_CACHE_DIR=$(find "$TEST_TMPDIR" -type d -name "$JEST_CACHE_NAME" -print -quit)
+
+# Check that the cache folder exists
+if [ -z "$JEST_CACHE_DIR" ]; then
+  echo "Error: '$JEST_CACHE_NAME' folder not found below '$TEST_TMPDIR'"
+  exit 1
+fi
+
+# Check that the folder was used for the cache
+if [ -z "$(ls -A "$JEST_CACHE_DIR")" ]; then
+  echo "Error: '$JEST_CACHE_NAME' folder at '$JEST_CACHE_DIR' is empty"
+  exit 1
+fi

jest/private/jest_config_template.mjs

@@ -86,6 +86,10 @@ if (userConfigShortPath) {
   }
 }
 
+// Default to using an isolated tmpdir
+config.cacheDirectory ||= path.join(process.env.TEST_TMPDIR, 'jest_cache');
+
+
 // Needed for Jest to walk the filesystem to find inputs.
 // See https://github.com/facebook/jest/pull/9351
 config.haste = { enableSymlinks: true };

jest/tests/BUILD.bazel

@@ -165,7 +165,7 @@ jest_test(
     node_modules = "//:node_modules",
 )
 
-# Case 11: Coverage reporting (see e2e test)
+# Case 12: Coverage reporting (see e2e test)
 jest_test(
     name = "case12",
     data = [
@@ -174,3 +174,13 @@ jest_test(
     ],
     node_modules = "//:node_modules",
 )
+
+# Case 13: jest_test uses TEST_TMPDIR (see e2e test)
+jest_test(
+    name = "case13",
+    config = "case13.jest.config.js",
+    data = [
+        "case13.test.js",
+    ],
+    node_modules = "//:node_modules",
+)

jest/tests/case13.jest.config.js

@@ -0,0 +1,5 @@
+module.exports = {
+  reporters: ["default"],
+  testEnvironment: "node",
+  testMatch: ["**/*.test.js"],
+};

jest/tests/case13.test.js

@@ -0,0 +1,3 @@
+test("it should work", () => {
+  expect(1).toBe(1);
+});