chore: re-add skip-test-if

This reverts commit 9c21f06.

Author: trivikr

scripts/skip-test-if.js

@@ -0,0 +1,56 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * This script can be used with `mocha --require ...` to support skipping
+ * tests if the current version of Node.js is too old.  For example, say
+ * a package's unit tests cannot run with Node.js 14, but the CI unit tests
+ * run all package test with that version.
+ *
+ * 1. Change this in "package.json":
+ *      "test": "nyc mocha ...",
+ *    to this:
+ *      "test": "SKIP_TEST_IF_NODE_OLDER_THAN=18 nyc mocha --require '../../../scripts/skip-test-if.js' ... ",
+ *    where `SKIP_TEST_IF_NODE_OLDER_THAN` indicates the minimum Node.js major
+ *    version.
+ *
+ * 2. ".tav.yml" blocks should set SKIP_TEST_IF_DISABLE=true to
+ *    disable the skipping. Via this in each test block:
+ *      env:
+ *        - SKIP_TEST_IF_DISABLE=true
+ */
+
+function skipTestIf() {
+  if (process.env.SKIP_TEST_IF_DISABLE) {
+    return;
+  }
+
+  const minNodeMajor = process.env.SKIP_TEST_IF_NODE_OLDER_THAN ?? Number(process.env.SKIP_TEST_IF_NODE_OLDER_THAN);
+  if (!minNodeMajor || isNaN(minNodeMajor)) {
+    console.warn('skip-test-if warning: set a minimum Node.js major version via SKIP_TEST_IF_NODE_OLDER_THAN=<num>');
+    return;
+  }
+
+  const nodeMajor = Number(process.versions.node.split('.')[0]);
+  if (nodeMajor < minNodeMajor) {
+    process.stderr.write(`skip-test-if: skipping tests on old Node.js (${nodeMajor} < ${minNodeMajor})\n`);
+    // "Skip" tests by exiting the process. Mocha is all in one process.
+    process.exit(0);
+  }
+}
+
+skipTestIf()
+