121 lines
3.7 KiB
JavaScript
121 lines
3.7 KiB
JavaScript
/**
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* Tests the $first and $last accumulators in $group.
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*/
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(function() {
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'use strict';
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const coll = db.jstests_aggregation_firstlast;
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coll.drop();
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/** Check expected $first and $last result values. */
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function assertFirstLast(expectedFirst, expectedLast, stages, expression) {
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let pipeline = [{$sort: {_id: 1}}];
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if (stages) {
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pipeline = pipeline.concat(stages);
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}
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expression = expression || '$b';
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pipeline.push({$group: {_id: '$a', first: {$first: expression}, last: {$last: expression}}});
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const result = coll.aggregate(pipeline).toArray();
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for (let i = 0; i < result.length; ++i) {
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if (result[i]._id === 1) {
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// Check results for group _id 1.
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assert.eq(expectedFirst, result[i].first);
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assert.eq(expectedLast, result[i].last);
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return;
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}
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}
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throw new Error('Expected $group _id "1" is missing');
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}
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// One document.
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assert.commandWorked(coll.insert({a: 1, b: 1}));
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assertFirstLast(1, 1);
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// Two documents.
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assert.commandWorked(coll.insert({a: 1, b: 2}));
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assertFirstLast(1, 2);
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// Three documents.
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assert.commandWorked(coll.insert({a: 1, b: 3}));
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assertFirstLast(1, 3);
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// Another 'a' key value does not affect outcome.
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assert(coll.drop());
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assert.commandWorked(coll.insert({a: 3, b: 0}));
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assert.commandWorked(coll.insert({a: 1, b: 1}));
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assert.commandWorked(coll.insert({a: 1, b: 2}));
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assert.commandWorked(coll.insert({a: 1, b: 3}));
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assert.commandWorked(coll.insert({a: 2, b: 0}));
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assertFirstLast(1, 3);
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// Additional pipeline stages do not affect outcome if order is maintained.
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assertFirstLast(1, 3, [{$project: {x: '$a', y: '$b'}}, {$project: {a: '$x', b: '$y'}}]);
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// Additional pipeline stages affect outcome if order is modified.
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assertFirstLast(3, 1, [{$sort: {b: -1}}]);
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// Skip and limit affect the results seen.
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assert(coll.drop());
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assert.commandWorked(coll.insert({a: 1, b: 1}));
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assert.commandWorked(coll.insert({a: 1, b: 2}));
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assert.commandWorked(coll.insert({a: 1, b: 3}));
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assertFirstLast(1, 2, [{$limit: 2}]);
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assertFirstLast(2, 3, [{$skip: 1}, {$limit: 2}]);
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assertFirstLast(2, 2, [{$skip: 1}, {$limit: 1}]);
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// Mixed type values.
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assert.commandWorked(coll.insert({a: 1, b: 'foo'}));
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assertFirstLast(1, 'foo');
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assert(coll.drop());
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assert.commandWorked(coll.insert({a: 1, b: 'bar'}));
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assert.commandWorked(coll.insert({a: 1, b: true}));
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assertFirstLast('bar', true);
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// Value null.
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assert(coll.drop());
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assert.commandWorked(coll.insert({a: 1, b: null}));
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assert.commandWorked(coll.insert({a: 1, b: 2}));
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assertFirstLast(null, 2);
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assert(coll.drop());
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assert.commandWorked(coll.insert({a: 1, b: 2}));
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assert.commandWorked(coll.insert({a: 1, b: null}));
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assertFirstLast(2, null);
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assert(coll.drop());
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assert.commandWorked(coll.insert({a: 1, b: null}));
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assert.commandWorked(coll.insert({a: 1, b: null}));
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assertFirstLast(null, null);
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// Value missing.
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assert(coll.drop());
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assert.commandWorked(coll.insert({a: 1}));
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assert.commandWorked(coll.insert({a: 1, b: 2}));
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assertFirstLast(undefined, 2);
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assert(coll.drop());
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assert.commandWorked(coll.insert({a: 1, b: 2}));
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assert.commandWorked(coll.insert({a: 1}));
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assertFirstLast(2, undefined);
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assert(coll.drop());
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assert.commandWorked(coll.insert({a: 1}));
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assert.commandWorked(coll.insert({a: 1}));
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assertFirstLast(undefined, undefined);
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// Dotted field.
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assert(coll.drop());
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assert.commandWorked(coll.insert({a: 1, b: [{c: 1}, {c: 2}]}));
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assert.commandWorked(coll.insert({a: 1, b: [{c: 6}, {}]}));
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assertFirstLast([1, 2], [6], [], '$b.c');
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// Computed expressions.
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assert(coll.drop());
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assert.commandWorked(coll.insert({a: 1, b: 1}));
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assert.commandWorked(coll.insert({a: 1, b: 2}));
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assertFirstLast(1, 0, [], {$mod: ['$b', 2]});
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assertFirstLast(0, 1, [], {$mod: [{$add: ['$b', 1]}, 2]});
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}());
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