doc.go

// Package assertions contains the implementations for all assertions which
// are referenced in goconvey's `convey` package
// (github.com/smarty/goconvey/convey) and gunit (github.com/smarty/gunit)
// for use with the So(...) method.
// They can also be used in traditional Go test functions and even in
// applications.
//
// https://smarty.com
//
// Many of the assertions lean heavily on work done by Aaron Jacobs in his excellent oglematchers library.
// (https://github.com/jacobsa/oglematchers)
// The ShouldResemble assertion leans heavily on work done by Daniel Jacques in his very helpful go-render library.
// (https://github.com/luci/go-render)
package assertions

import (
	"fmt"
	"runtime"
)

// By default, we use a no-op serializer. The actual Serializer provides a JSON
// representation of failure results on selected assertions so the goconvey
// web UI can display a convenient diff.
var serializer Serializer = new(noopSerializer)

// GoConveyMode provides control over JSON serialization of failures. When
// using the assertions in this package from the convey package JSON results
// are very helpful and can be rendered in a DIFF view. In that case, this function
// will be called with a true value to enable the JSON serialization. By default,
// the assertions in this package will not serializer a JSON result, making
// standalone usage more convenient.
func GoConveyMode(yes bool) {
	if yes {
		serializer = newSerializer()
	} else {
		serializer = new(noopSerializer)
	}
}

type testingT interface {
	Error(args ...any)
}

type Assertion struct {
	t      testingT
	failed bool
}

// New swallows the *testing.T struct and prints failed assertions using t.Error.
// Example: assertions.New(t).So(1, should.Equal, 1)
func New(t testingT) *Assertion {
	return &Assertion{t: t}
}

// Failed reports whether any calls to So (on this Assertion instance) have failed.
func (this *Assertion) Failed() bool {
	return this.failed
}

// So calls the standalone So function and additionally, calls t.Error in failure scenarios.
func (this *Assertion) So(actual any, assert SoFunc, expected ...any) bool {
	ok, result := So(actual, assert, expected...)
	if !ok {
		this.failed = true
		_, file, line, _ := runtime.Caller(1)
		this.t.Error(fmt.Sprintf("\n%s:%d\n%s", file, line, result))
	}
	return ok
}

// So is a convenience function (as opposed to an inconvenience function?)
// for running assertions on arbitrary arguments in any context, be it for testing or even
// application logging. It allows you to perform assertion-like behavior (and get nicely
// formatted messages detailing discrepancies) but without the program blowing up or panicking.
// All that is required is to import this package and call `So` with one of the assertions
// exported by this package as the second parameter.
// The first return parameter is a boolean indicating if the assertion was true. The second
// return parameter is the well-formatted message showing why an assertion was incorrect, or
// blank if the assertion was correct.
//
// Example:
//
//	if ok, message := So(x, ShouldBeGreaterThan, y); !ok {
//	     log.Println(message)
//	}
//
// For an alternative implementation of So (that provides more flexible return options)
// see the `So` function in the package at github.com/smarty/assertions/assert.
func So(actual any, assert SoFunc, expected ...any) (bool, string) {
	result := so(actual, assert, expected...)
	return len(result) == 0, result
}

// so is like So, except that it only returns the string message, which is blank if the
// assertion passed. Used to facilitate testing.
func so(actual any, assert SoFunc, expected ...any) string {
	return assert(actual, expected...)
}

// SoFunc is an alias for a function with a signature that the So()
// function can handle. Any future or custom assertions should conform to this
// method signature. The return value should be an empty string if the SoFunc
// passes and a well-formed failure message if not.
type SoFunc func(actual any, expected ...any) string

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