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Guided practice · Dependencies and Test Doubles

Guided Lab: Dependencies and Test Doubles in Software Testing Fundamentals

Software Testing Fundamentals — Dependencies and Test Doubles lab: Test a component with one controlled dependency, then remove a flaky source such as real time, network, or shared mutable state and confirm the test stays deterministic.

55 min 5 field checks Safety: Moderate
Outcome summary

Know what success looks like before you begin

What you will produce

Complete the lab with a working dependencies and test doubles exercise with a documented technical result.

Evidence to save

Save verification evidence: the module-specific command, output, test, rendered state, query result, log, or measurement that proves the exercise worked.

Pass criteria
  • I completed the module-specific practice task.
  • I produced a working dependencies and test doubles exercise with a documented technical result.
  • I saved the module-specific command, output, test, rendered state, query result, log, or measurement that proves the exercise worked.
  • I diagnosed and corrected one realistic Dependencies and Test Doubles failure.
Common failure signal

Stop before using production credentials, important data, shared permissions, live infrastructure, or destructive commands that are not required by the lab.

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Lab brief

Know the problem and the evidence you need

The situation

Test a component with one controlled dependency, then remove a flaky source such as real time, network, or shared mutable state and confirm the test stays deterministic.

Your finished record

a working dependencies and test doubles exercise with a documented technical result

Complete the task, verify the module-specific command, output, test, rendered state, query result, log, or measurement that proves the exercise worked, then diagnose one failure that is specific to Dependencies and Test Doubles.

Why this matters

Control dependencies only where needed, keep tests deterministic, and make failures point to product behavior rather than unstable clocks, networks, or shared state.

Safety and setup

Prepare before changing anything

Have this ready

  • Open a small local project or disposable lab environment.
  • Confirm the runtime, toolchain, or service needed for the module.
  • Prepare one valid input and one invalid or boundary input.
Field checks

Run the lab

Complete one check at a time. Record the evidence before moving on.

0 of 5 checks complete
Interpret results

Match the evidence to the next action

If you seeNext action

The expected result appears and the boundary case behaves correctly

Save the result and continue to the module checkpoint.

The normal case works but the failure or boundary case does not

Return to the diagnostic step and inspect the module-specific state or output before changing more code.

The result changes between runs

Compare the relevant input, dependency, configuration, data, state, or runtime version for this module.

Decision point

Choose the next action

Complete the lab when you can reproduce the working result, explain the important module decision, and recover from the tested failure.

Completion

Confirm the evidence you produced

Finished record: a working dependencies and test doubles exercise with a documented technical result

  • I completed the module-specific practice task.
  • I produced a working dependencies and test doubles exercise with a documented technical result.
  • I saved the module-specific command, output, test, rendered state, query result, log, or measurement that proves the exercise worked.
  • I diagnosed and corrected one realistic Dependencies and Test Doubles failure.

Editorial review date:

Reviewed by: David Pac

Review method: Curriculum review plus automated schema, rendering, internal-link, representative learning-needs, and regression checks.