Test double
computing object that substitutes for another object for use in testing
A test double is software used in software test automation that satisfies a dependency so that the test need not depend on production code. A test double provides functionality via an interface that the software under test cannot distinguish from production code.
A programmer generally uses a test double to isolate the behavior of the consuming code from the rest of the codebase.
A test double is usually a simplified version of the production code and may include capabilities specific to testing.
Test doubles are used to build test harnesses.
Uses
A test double may be used to simplify tests, increase speed of execution or allow for deterministic results of an action.
For example, a program that uses a database server is relatively slow and consumes significant system resources, which impedes testing productivity. A test might require data from the database that under normal system activity is regularly changing, so provides non-deterministic outputs for any given query. A test double can provide a static value instead of accessing a real database, thereby both avoiding network or system calls, and changing data.
A test double may also be used to test part of the system that is ready for testing even if its dependencies are not.
The public source identifies “Test double” as computing object that substitutes for another object for use in testing. This brief keeps that definition visible, then builds a research path around Test, double and computing.
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Stable identifiers, scientific names and standards terminology offer the best bridge between this overview and specialist evidence. The source revision retrieved here is dated Aug 13, 2026. The linked authority identifier is Q11319265. None of the 0 selected statements returned an explicit reference.
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This entry incorporates text from “Test double” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.