Force measurement of a metric

[dicksnel]

User story

As a user I want to see the new measurement value for a metric as soon as possible so that I know that the changes I made to the metric or source configuration or changes in the source give the expected results.

Acceptance criteria

• A user can force Quality-time to measure a metric as soon as possible.

Assumptions

• Show in the frontend when the collector is measuring a metric  #7760 is implemented first, otherwise this feature would not provide any feedback to the user about what is happening.
• Show whether the latest measurement of metric has been done with the current configuration of its source(s) #3134 will imply that they are being measured.

Out of scope

• Showing that Quality-time is currently measuring a metric, see Show in the frontend when the collector is measuring a metric  #7760.
• Showing that the config has changed and the current measurement value was measured with the old config, see Show whether the latest measurement of metric has been done with the current configuration of its source(s) #3134.

Tasks

Components

Frontend

• Add button "Measure now" next to the metric position buttons.
• When the button is clicked, the frontend tells the API-server to remove the hash from the latest measurement of the metric.
• Make the button inactive while the metric is being measured.

Collector

• Insert a new measurement after a measurement was requested, even if the measurement was not changed. This lets the frontend get a new measurement count via the number of measurements server-sent events end point so it knows the requested measurement was done.

Shared code

• Include a measurement_requested flag in the latest measurement summary so the frontend knows a measurement is pending.

Feature tests

• Add a scenario for requesting a measurement.

Documentation

• Update changelog

[fniessink]

I've created a separate issue for the error message timestamps: #980