The progress bar is divided into two components - one is a numerical indicator and the other is a risk projection.
When there are no failing tests, the numerical indicator shows a risk percentage that is calculated by NCrunch with close consideration to the number of impacted tests in your solution. A higher percentage gives a higher possibility that there are tests that may fail given the current state of your solution. A risk factor of 100% indicates that all tests within the solution are considered to be impacted and therefore any of these tests have a chance of failing. This risk percentage can be particularly useful on large solutions with many long running tests, as it can help to make an informed decision on whether or not to commit code into a source control system.
When there are failing tests within the solution, the numerical indicator will show the number of failing tests. Clicking on the indicator will open the tests window with the filter set to show the tests that are failing.
The risk projection serves two purposes. The first is to show the overall progress of NCrunch relative to the amount of work in its processing queue - this is in the form of a normal creeping progress bar that is green when tests are passing and red when failures exist.
The second purpose is to show a projection of risk over time. This is visible as a darker section of the projection and describes the risk percentage at any point during NCrunch's processing.
As NCrunch has the ability to process tests in parallel, the risk projection needs to construct meaningful estimates on the total execution time of all tests in the test pipeline. These estimates take into account all aspects of parallelisation, including resource usage etc. You can view the estimated execution time of the test pipeline by hovering your mouse over the risk projection.