How to debug ‘NetworkError: Failed to execute ‘send’ on ‘XMLHttpRequest” in Karma tests

Running tests that fail without any useful information may be very frustrating. I faced this problem with Karma tests for Angular 4 application. I made few changes in my code and then got message: ‘Uncaught NetworkError: Failed to execute ‘send’ on ‘XMLHttpRequest’ with no explanation what’s wrong. It seems to be a Karma/Angular/CLI bug and […]

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