Industrial Software Integration & APIs worked example

Integration Test Workload at 25% retest and regression allowance: a worked example

Suppose retest and regression allowance falls to 25%. This page works the full calculation at that level so you can see exactly which result moves and by how much. Estimate the total hours required for integration testing including test case execution, defect verification, and regression testing across connected manufacturing systems.

The inputs for this scenario

  • Test cases to execute: 120 test cases (held at the documented default)
  • Test execution rate: 4 cases / hour (held at the documented default)
  • Retest and regression allowance: 25 % (the input this scenario stresses; the baseline uses 35)

Working through the calculation

  • The calculation starts from the formula this tool documents: Base test execution hours = test cases / test execution rate.
  • Total integration test hours works out to 37.5 hr at these inputs, and this is the headline figure for the scenario.
  • Base test execution hours works out to 30 hr at these inputs.
  • Retest and regression hours added works out to 25 % at these inputs.
  • Test execution rate (cases/hour) works out to 4 pieces / min at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where retest and regression allowance sits at 35% and the headline result is 40.5 hr, this scenario comes in 7.41% below the baseline at 37.5 hr.
  • It computes the total integration test effort in hours, including a buffer for re-running cases after defects are fixed. When the numbers land here, the stressed input is the lever to work; the walkthrough above shows exactly how much each output recovers as it climbs back toward the baseline.

Results at a glance

  • Total integration test hours: 37.5 hr (headline result)
  • Base test execution hours: 30 hr
  • Retest and regression hours added: 25 %
  • Test execution rate (cases/hour): 4 pieces / min

Run it with your numbers

  • To rerun this with your own numbers, open the live Integration Test Workload calculator, set retest and regression allowance to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.