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// Package main demonstrates the use of the IsNull method from github.com/olekukonko/errors.
// It tests various scenarios involving nil errors, empty errors, errors with null or non-null
// context, and MultiError instances, showcasing how IsNull determines nullability based on content
// and context, particularly with SQL null types.
package main
import (
"database/sql"
"fmt"
"github.com/olekukonko/errors"
)
// main is the entry point, illustrating the behavior of IsNull across different error cases.
// It checks nil errors, empty errors, context with SQL null values, and MultiError instances.
func main() {
// Case 1: Nil error
// Test if a nil error is considered null
var err error = nil
if errors.IsNull(err) {
fmt.Println("Nil error is null") // Expect true: nil errors are always null
}
// Case 2: Empty error
// Test if an empty error (no message) is considered null
err = errors.New("")
if errors.IsNull(err) {
fmt.Println("Empty error is null")
} else {
fmt.Println("Empty error is not null") // Expect false: empty message but no null context
}
// Case 3: Error with null context
// Test if an error with a null SQL context value is considered null
nullString := sql.NullString{Valid: false}
err = errors.New("").With("data", nullString)
if errors.IsNull(err) {
fmt.Println("Error with null context is null") // Expect true: all context is null
}
// Case 4: Error with non-null context
// Test if an error with a valid SQL context value is not null
validString := sql.NullString{String: "test", Valid: true}
err = errors.New("").With("data", validString)
if errors.IsNull(err) {
fmt.Println("Error with valid context is null")
} else {
fmt.Println("Error with valid context is not null") // Expect false: valid context present
}
// Case 5: Empty MultiError
// Test if an empty MultiError is considered null
multi := errors.NewMultiError()
if multi.IsNull() {
fmt.Println("Empty MultiError is null") // Expect true: no errors in MultiError
}
// Case 6: MultiError with null error
// Test if a MultiError containing a null error is considered null
multi.Add(errors.New("").With("data", nullString))
if multi.IsNull() {
fmt.Println("MultiError with null error is null") // Expect true: only null errors
}
// Case 7: MultiError with non-null error
// Test if a MultiError with mixed errors (null and non-null) is not null
multi.Add(errors.New("real error"))
if multi.IsNull() {
fmt.Println("MultiError with mixed errors is null")
} else {
fmt.Println("MultiError with mixed errors is not null") // Expect false: contains non-null error
}
}
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