40 lines
1.1 KiB
JavaScript
40 lines
1.1 KiB
JavaScript
// $substr returns an empty string if the position argument is out of bounds. SERVER-6186
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t = db.jstests_aggregation_server6186;
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t.drop();
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t.save({});
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function substr(string, pos, n) {
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return t.aggregate({$project: {a: {$substr: [string, pos, n]}}}).toArray()[0].a;
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}
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function expectedSubstr(string, pos, n) {
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if (pos < 0) {
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// A negative value is interpreted as a large unsigned int, and is expected to be out of
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// bounds.
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return "";
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}
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if (n < 0) {
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// A negative value is interpreted as a large unsigned int, expected to exceed the length
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// of the string. Passing the string length is functionally equivalent.
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n = string.length;
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}
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return string.substring(pos, pos + n);
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}
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function assertSubstr(string, pos, n) {
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assert.eq(expectedSubstr(string, pos, n), substr(string, pos, n));
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}
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function checkVariousSubstrings(string) {
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for (pos = -2; pos < 5; ++pos) {
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for (n = -2; n < 7; ++n) {
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assertSubstr(string, pos, n);
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}
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}
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}
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checkVariousSubstrings("abc");
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checkVariousSubstrings("");
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