ITelemetryClient to facilitate testing/mocking

[thomhurst]

Fix Issue #342 .

Changes

An interface of ITelemetryClient, containing all the public methods/properties available on TelemetryClient.
This allows consumers to inject an interface, rather than a concrete implementation, into their classes, which makes mocking and testing easier for consumers.

This doesn't change any behaviour around TelemetryClient currently. It just adds the ability to also inject in ITelemetryClient via DI. You can still inject in TelemetryClient. The choice is up to the consumer. Both will work.

Checklist

• I ran Unit Tests locally.
• CHANGELOG.md updated with one line description of the fix, and a link to the original issue if available.

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[304NotModified]

Great work!

[thomhurst]

/AzurePipelines run

[azure-pipelines]

Commenter does not have sufficient privileges for PR 2761 in repo microsoft/ApplicationInsights-dotnet

[cijothomas]

We should be very careful adding new public APIs in this repo. The long term goal would be to leverage OpenTelemetry, so try to keep the changes here minimal, unless critical.

[thomhurst]

We should be very careful adding new public APIs in this repo. The long term goal would be to leverage OpenTelemetry, so try to keep the changes here minimal, unless critical.

It's not really adding an API. It's the exact same API as current, but with the option of calling the existing methods on an interface rather than the concrete implementation.

The long term goal is fine for when it happens, but it's still a WIP and many people are left with using TelemetryClient for now until it's built out a bit more.

This has been an open issue for years and people want to be able to write tests so that they feel comfortable with their logging code.

Can I ask why it's so contentious to put an interface behind the TelemetryClient?

[304NotModified]

Please accept this small change in code (no breaking changes, no extra public api) that will result in great possibilities with automatic testing.

[304NotModified]

Polite bump @cijothomas. There is no change needed? The public api hasn't changed

[304NotModified]

@TimothyMothra could please help us in getting this PR merged? (you're the top contributor of this repo)

[aligneddev]

This looks good to me. I was hopping their was already an interface. This change would have simplified my mocking

[thomhurst]

Unfortunately Microsoft don't seem to be willing to merge this for some reason, so I don't think you'll have any luck

[aligneddev]

@thomhurst at least the example in #342 was straight forward and I got it to work. Thanks for trying.
Happy Thanksgiving! 🦃