mongodb/jstests/noPassthrough/agg_explain_read_concern.js

// TODO: SERVER-34388 Simplify this test by wrapping all the statements
// in one transaction once a failing command won't abort the transaction
/**
 * Test that explained aggregation commands behave correctly with the readConcern option.
 */
(function() {
    "use strict";

    load("jstests/multiVersion/libs/causal_consistency_helpers.js");

    // Skip this test if running with --nojournal and WiredTiger.
    if (jsTest.options().noJournal &&
        (!jsTest.options().storageEngine || jsTest.options().storageEngine === "wiredTiger")) {
        print("Skipping test because running WiredTiger without journaling isn't a valid" +
              " replica set configuration");
        return;
    }

    if (!supportsMajorityReadConcern()) {
        jsTestLog("Skipping test since storage engine doesn't support majority read concern.");
        return;
    }

    const rst = new ReplSetTest(
        {name: "aggExplainReadConcernSet", nodes: 1, nodeOptions: {enableMajorityReadConcern: ""}});
    rst.startSet();
    rst.initiate();

    const primary = rst.getPrimary();
    const session = primary.getDB("test").getMongo().startSession({causalConsistency: false});
    const sessionDB = session.getDatabase("test");
    const coll = sessionDB.agg_explain_read_concern;

    // Test that explain is legal with readConcern "local".
    assert.commandWorked(coll.explain().aggregate([], {readConcern: {level: "local"}}));
    assert.commandWorked(sessionDB.runCommand(
        {aggregate: coll.getName(), pipeline: [], explain: true, readConcern: {level: "local"}}));
    assert.commandWorked(sessionDB.runCommand({
        explain: {aggregate: coll.getName(), pipeline: [], cursor: {}},
        readConcern: {level: "local"}
    }));

    // Test that explain is illegal with other readConcern levels.
    const nonLocalReadConcerns = ["majority", "available", "linearizable", "snapshot"];
    nonLocalReadConcerns.forEach(function(readConcernLevel) {
        let aggCmd = {
            aggregate: coll.getName(),
            pipeline: [],
            explain: true,
            readConcern: {level: readConcernLevel}
        };
        let explainCmd = {
            explain: {aggregate: coll.getName(), pipeline: [], cursor: {}},
            readConcern: {level: readConcernLevel}
        };

        if (readConcernLevel === "snapshot") {
            if (!sessionDB.serverStatus().storageEngine.supportsSnapshotReadConcern) {
                return;
            }
            aggCmd.txnNumber = NumberLong(0);
            explainCmd.txnNumber = NumberLong(1);

        } else {
            assert.throws(
                () => coll.explain().aggregate([], {readConcern: {level: readConcernLevel}}));
        }

        let cmdRes = sessionDB.runCommand(aggCmd);
        assert.commandFailedWithCode(cmdRes, ErrorCodes.InvalidOptions, tojson(cmdRes));
        let expectedErrStr = "aggregate command does not support non-local readConcern";
        assert.neq(cmdRes.errmsg.indexOf(expectedErrStr), -1, tojson(cmdRes));

        cmdRes = sessionDB.runCommand(explainCmd);
        assert.commandFailedWithCode(cmdRes, ErrorCodes.InvalidOptions, tojson(cmdRes));
        expectedErrStr = "Command does not support read concern";
        assert.neq(cmdRes.errmsg.indexOf(expectedErrStr), -1, tojson(cmdRes));
    });

    session.endSession();
    rst.stopSet();
}());