Why Doesn't `fmt.Println()` Work in Go Tests, and How Can I Print Debugging Information?

Printing in Go Tests with the "testing" Package

Imagine you're troubleshooting a failing test and want to add print statements for debugging, but nothing shows up when you run the test. Why is that?

In Go, the built-in fmt.Println() statements don't work as expected within tests. Instead, the "testing" package provides alternative methods for printing.

The structs testing.T and testing.B have .Log and .Logf methods that offer functionalities similar to fmt.Print and fmt.Printf. These methods allow you to print statements within tests.

Example:

func TestPrintSomething(t *testing.T) {
    t.Log("Say hi")
}

However, even with these methods, the output might not be immediately visible. To see the log messages, you need to provide the -v flag (for verbosity) when running the tests:

go test -v

With the -v flag, the log messages will be printed alongside the test results, giving you the debugging information you need.

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