SERVER-51112 Add runFeatureFlagMultiversionTest helper for targeted upgrade/downgrade tests

1 files changed, 61 insertions, 0 deletions

diff --git a/jstests/multiVersion/genericSetFCVUsage/run_feature_flag_multiversion_test.js b/jstests/multiVersion/genericSetFCVUsage/run_feature_flag_multiversion_test.js
new file mode 100644
index 00000000000..41d8d9ba898
--- /dev/null
+++ b/jstests/multiVersion/genericSetFCVUsage/run_feature_flag_multiversion_test.js
@@ -0,0 +1,61 @@
+/**
+ * Tests the behavior of the 'runFeatureFlagMultiversionTest' helper.
+ * This test requires that the featureFlagToaster and featureFlagSpoon parameters to be enabled and
+ * the featureFlagFryer parameter to be disabled.
+ *
+ * Add test tags for the feature flags depended on by this test.
+ * @tags: [featureFlagToaster, featureFlagSpoon]
+ */
+
+(function() {
+'use strict';
+
+let numLastLTSRuns = 0;
+let numLastContRuns = 0;
+
+function runTest(downgradeFCV) {
+    let name = "feature_flag_test";
+    let nodes = {n0: {binVersion: "latest"}};
+    let rst = new ReplSetTest({name: name, nodes: nodes});
+    rst.startSet();
+    rst.initiate();
+
+    let primary = rst.getPrimary();
+    let adminDB = primary.getDB("admin");
+    assert.commandWorked(adminDB.adminCommand({setFeatureCompatibilityVersion: downgradeFCV}));
+    checkFCV(adminDB, downgradeFCV);
+    if (downgradeFCV === lastLTSFCV) {
+        numLastLTSRuns++;
+    } else {
+        numLastContRuns++;
+    }
+    rst.stopSet();
+}
+
+try {
+    // We expect the test run to fail when using a non-existent feature flag.
+    runFeatureFlagMultiversionTest("nonExistentFeatureFlag", runTest);
+} catch (error) {
+}
+
+// No tests should have been run when a non-existent feature flag is passed in.
+assert.eq(numLastLTSRuns, 0);
+assert.eq(numLastContRuns, 0);
+
+// No tests should have been run when a disabled feature flag is passed in.
+runFeatureFlagMultiversionTest("featureFlagFryer", runTest);
+assert.eq(numLastLTSRuns, 0);
+assert.eq(numLastContRuns, 0);
+
+// Pass in a feature flag that is slated for release in the latest version. This should run against
+// both the last-lts and last-continuous FCV.
+runFeatureFlagMultiversionTest("featureFlagToaster", runTest);
+assert.eq(numLastLTSRuns, 1);
+assert.eq(numLastContRuns, 1);
+
+// Pass in a feature flag that was released in an older version. This should only run against the
+// last-lts FCV.
+runFeatureFlagMultiversionTest("featureFlagSpoon", runTest);
+assert.eq(numLastLTSRuns, 2);
+assert.eq(numLastContRuns, 1);
+})();
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