context.gno

 1package expect
 2
 3import (
 4	"strings"
 5
 6	"gno.land/p/nt/ufmt/v0"
 7)
 8
 9const defaultAssertFailMsg = "assert expectation failed"
10
11// NewContext creates a new testing context.
12func NewContext(t TestingT) Context {
13	return Context{t: t}
14}
15
16// Context preserves the current testing context.
17type Context struct {
18	t       TestingT
19	negated bool
20	prefix  string
21}
22
23// T returns context's testing T instance.
24func (c Context) T() TestingT {
25	if c.t == nil {
26		panic("expect: context is not initialized")
27	}
28	return c.t
29}
30
31// Prefix returns context's error prefix.
32func (c Context) Prefix() string {
33	return c.prefix
34}
35
36// IsNegated checks if current context negates current assert expectations.
37func (c Context) IsNegated() bool {
38	return c.negated
39}
40
41// CheckExpectation checks an assert expectation and calls a callback on fail.
42// It returns true when the asserted expectation fails.
43// Callback is called when a negated assertion succeeds or when non negated assertion fails.
44func (c Context) CheckExpectation(success bool, cb func(Context) string) bool {
45	failed := (c.negated && success) || (!c.negated && !success)
46	if failed {
47		msg := cb(c)
48		if strings.TrimSpace(msg) == "" {
49			msg = defaultAssertFailMsg
50		}
51
52		c.Fail(msg)
53	}
54	return failed
55}
56
57// Fail makes the current test fail with a custom message.
58func (c Context) Fail(msg string, args ...any) {
59	if c.prefix != "" {
60		msg = c.prefix + " - " + msg
61	}
62
63	c.t.Fatalf(msg, args...)
64}
65
66// TestingT defines a minimal interface for `testing.T` instances.
67type TestingT interface {
68	Helper()
69	Fatal(args ...any)
70	Fatalf(format string, args ...any)
71}
72
73// MockTestingT creates a new testing mock that writes testing output to a string builder.
74func MockTestingT(output *strings.Builder) TestingT {
75	return &testingT{output}
76}
77
78type testingT struct{ buf *strings.Builder }
79
80func (testingT) Helper()                          {}
81func (t testingT) Fatal(args ...any)              { t.buf.WriteString(ufmt.Sprintln(args...)) }
82func (t testingT) Fatalf(fmt string, args ...any) { t.buf.WriteString(ufmt.Sprintf(fmt+"\n", args...)) }