text: // Test that MapReduce only runs when certain arguments are explicit null. This is required because
  // the Java Driver adds null as an argument to these fields if they are missing in the command from
  // the user.
  // @tags: [
  //   # mapReduce does not support afterClusterTime.
  //   does_not_support_causal_consistency,
  //   does_not_support_stepdowns,
  //   uses_map_reduce_with_temp_collections,
  // ]
  (function() {
  "use strict";
  
  const coll = db.mr_null_test;
  const outColl = db.mr_null_test_out;
  assert.commandWorked(coll.insert({val: 1}));
  
  function mapFunc() {
      emit(this.val, 1);
  }
  function reduceFunc(k, v) {
      return Array.sum(v);
  }
  
  // Test that finalize can be explicit null.
  assert.commandWorked(db.runCommand({
      mapReduce: coll.getName(),
      map: mapFunc,
      reduce: reduceFunc,
      finalize: null,
      out: {merge: outColl.getName()}
  }));
  
  // Test that query can be explicit null.
  assert.commandWorked(db.runCommand({
      mapReduce: coll.getName(),
      map: mapFunc,
      reduce: reduceFunc,
      query: null,
      out: {merge: outColl.getName()}
  }));
  
  // Test that sort can be explicit null.
  assert.commandWorked(db.runCommand({
      mapReduce: coll.getName(),
      map: mapFunc,
      reduce: reduceFunc,
      sort: null,
      out: {merge: outColl.getName()}
  }));
  
  // Test that scope can be explicit null.
  assert.commandWorked(db.runCommand({
      mapReduce: coll.getName(),
      map: mapFunc,
      reduce: reduceFunc,
      scope: null,
      out: {merge: outColl.getName()}
  }));
  })();
  