t = db.getCollection( "where1" );
t.drop();

t.save( { a : 1 } );
t.save( { a : 2 } );
t.save( { a : 3 } );

assert.eq( 1 , t.find( function(){ return this.a == 2; } ).length() , "A" );

assert.eq( 1 , t.find( { $where : "return this.a == 2" } ).toArray().length , "B" );
assert.eq( 1 , t.find( { $where : "this.a == 2" } ).toArray().length , "C" );

assert.eq( 1 , t.find( "this.a == 2" ).toArray().length , "D" );

// SERVER-12117
// positional $ projection should fail on a $where query
assert.throws( function() { t.find( { $where : "return this.a;" }, { 'a.$' : 1 } ).itcount(); } );

// SERVER-12439: $where must be top-level
assert.throws( function() { t.find( { a: 1, b: { $where : "this.a;" } } ).itcount(); } );
assert.throws( function() { t.find( { a: { $where : "this.a;" } } ).itcount(); } );
assert.throws( function() {
    t.find( { a: { $elemMatch : { $where : "this.a;" } } } ).itcount();
} );
assert.throws( function() {
    t.find( { a: 3, "b.c": { $where : "this.a;" } } ).itcount();
} );