[receiver/googlecloudmonitoringreceiver] Implement Unit Tests for Core Functionality

[scaletech-milan]

Component(s)

receiver/googlecloudmonitoring

Is your feature request related to a problem? Please describe.

A new receiver, googlecloudmonitoringreceiver, has been created to ingest and process metrics from Google Cloud Monitoring. The initial implementation spans multiple PRs, covering the core functionality and setup:

• #34015
• #34677
• #35136
• #35828

The component files can be found here.

To ensure robustness and meet contribution standards, unit tests need to be implemented in a separate PR.

Describe the solution you'd like

The unit tests should be designed to cover:

• Separate Testing for Core Functions: Test the Start and Scrape functions individually to ensure their correct functionality in isolation.
• End-to-End Flow Testing: Simulate the entire receiver lifecycle, calling both functions together to validate the complete flow of metric ingestion and processing.
• Maximizing Coverage: Cover as many edge cases, input variations, and scenarios as possible to ensure robust testing.

Describe alternatives you've considered

No response

Additional context

Unit tests are essential for ensuring the reliability of the receiver and maintaining OpenTelemetry's quality standards.

[github-actions]

Pinging code owners:

• receiver/googlecloudmonitoring: @dashpole @TylerHelmuth @abhishek-at-cloudwerx

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