How do I assert the exception thrown in the constructor?

Question

In my service class, I have this constructor.

public IngestService()
{
    _extractedFilePath = configuration["Path:Ingest"];

    if (string.IsNullOrEmpty(_extractedFilePath))
    {
        _logger.LogError($"Invalid conguration. Check appsettings.");
        throw new Exception("Invalid conguration. Check appsettings.");
    }
}

and I have this test using XUnit

[Fact]
public async Task WhenInvalidConstructor_ThenShouldThrowETest() {
        var _ingestService = new IngestService();
}

When I debug it, it can reach the constructor. But how do I capture the exception and assert the exception message "Invalid conguration. Check appsettings."?

This might help you: https://stackoverflow.com/questions/45017295/assert-an-exception-using-xunit — Shai Aharoni, Jul 11 '21 at 07:57
BTW, [a good read](https://stackoverflow.com/questions/77639/when-is-it-right-for-a-constructor-to-throw-an-exception) — , Jul 11 '21 at 08:04
@ShaiAharoni, I tried but unable to get it since it is not calling any method but the constructor. If call any method, I can get the exception message. — Steve, Jul 11 '21 at 08:51
Does this answer your question? [Assert an Exception using XUnit](https://stackoverflow.com/questions/45017295/assert-an-exception-using-xunit) — Progman, Jul 12 '21 at 14:56

score 3 · Accepted Answer · answered Jul 12 '21 at 12:05

3

Try this:

    Exception actualException = Assert.Throws<Exception>(() => new IngestService());
    Assert.Equal("Invalid conguration. Check appsettings.", actualException.Message);

answered Jul 12 '21 at 12:05

Stam

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How do I assert the exception thrown in the constructor?

1 Answers1