Go error handling, wrapping with errors.Is and As, panic and recover, go test, benchmarks, go modules and tooling.
42 cards · basic cards · AI-written, checked twice. Edit anything.
- What methods must a type implement to satisfy the error interface?
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A single Error() method that returns a string- How do you create a simple error using the errors package?
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errors.New("error message")- How do you wrap an error to preserve it for errors.Is and errors.As?
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fmt.Errorf("context: %w", err)- What does errors.Is check?
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Whether an error in the chain matches a target error value- What does errors.As do?
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Unwraps an error chain and assigns the first matching type to a variable- What does errors.Unwrap return?
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The error wrapped by %w in the argument, or nil if not wrapped- What is a sentinel error?
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A predefined error variable (like var ErrNotFound = errors.New("not found")) used for comparison with errors.Is- How do you create a custom error type?
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Define a type with an Error() method that returns a string- When should you wrap an error versus returning it unwrapped?
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Wrap it to add context; return unwrapped at API boundaries where wrapping adds no value- Name one scenario where panic is appropriate in Go.
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Programmer error or internal invariant violation (not user input or recoverable failures)- Should invalid user input cause a panic or return an error?
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Return an error (panic is for unrecoverable programmer errors)- What does recover() do?
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Stops a panic and returns the value passed to panic, or nil if not panicking- Where must you call recover() for it to work?
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Inside a defer statement- Can recover() in one goroutine catch a panic from a different goroutine?
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No, recover only catches panics in the same goroutine- What does the go test command do?
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Runs all *_test.go files in the current package and reports results
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