text: /**
   * Tests that removing invalid index options in collMod has no negative consequences for replica
   * sets running with earlier versions of the server.
   *
   * @tags: [requires_replication]
   */
  (function() {
  "use strict";
  
  load("jstests/libs/fail_point_util.js");
  
  var nodes = {
      n1: {binVersion: "latest"},
      n2: {binVersion: "last-lts"},
  };
  
  var rst = new ReplSetTest({nodes: nodes});
  rst.startSet();
  rst.initiate();
  
  const dbName = "test";
  const collName = jsTestName();
  
  const primary = rst.getPrimary();
  const secondary = rst.getSecondary();
  
  const primaryDB = primary.getDB(dbName);
  const primaryColl = primaryDB.getCollection(collName);
  
  const secondaryDB = secondary.getDB(dbName);
  
  // In earlier versions of the server, users were able to add invalid index options when creating an
  // index. This fail point allows us to skip validating index options to simulate the old behaviour.
  const fpPrimary = configureFailPoint(primaryDB, "skipIndexCreateFieldNameValidation");
  const fpSecondary = configureFailPoint(secondaryDB, "skipIndexCreateFieldNameValidation");
  
  // Create indexes with invalid options.
  assert.commandWorked(primaryColl.createIndex({x: 1}, {safe: true, sparse: true, force: false}));
  assert.commandWorked(primaryColl.createIndex({y: 1}, {sparse: true}));
  assert.commandWorked(primaryColl.createIndex({z: 1}, {xyz: false}));
  
  fpPrimary.off();
  fpSecondary.off();
  
  // Verify that the primary (latest) and secondary (last-lts) detect invalid index options.
  let validateRes = assert.commandWorked(primaryDB.runCommand({validate: collName}));
  assert(!validateRes.valid);
  
  validateRes = assert.commandWorked(secondaryDB.runCommand({validate: collName}));
  assert(!validateRes.valid);
  
  // Use collMod to remove the invalid index options in the collection.
  assert.commandWorked(primaryDB.runCommand({collMod: collName}));
  
  // Removing unknown field from index spec.
  checkLog.containsJson(primary, 23878, {fieldName: "safe"});
  checkLog.containsJson(primary, 23878, {fieldName: "force"});
  checkLog.containsJson(primary, 23878, {fieldName: "xyz"});
  
  checkLog.containsJson(secondary, 23878, {fieldName: "safe"});
  checkLog.containsJson(secondary, 23878, {fieldName: "force"});
  checkLog.containsJson(secondary, 23878, {fieldName: "xyz"});
  
  // Verify that the index no longer has invalid index options.
  validateRes = assert.commandWorked(primaryDB.runCommand({validate: collName}));
  assert(validateRes.valid);
  
  validateRes = assert.commandWorked(secondaryDB.runCommand({validate: collName}));
  assert(validateRes.valid);
  
  rst.stopSet();
  })();
  