feat: add Nil and NotNil.

Author: ghosind

assertion.go

@@ -25,6 +25,16 @@ func (a *Assertion) NotDeepEqual(actual, expect any, message ...string) error {
 	return NotDeepEqual(a.t, actual, expect, message...)
 }
 
+// Nil tests a value is nil or not, and it'll failed when the value is not nil.
+func (a *Assertion) Nil(val any, message ...string) error {
+	return Nil(a.t, val, message...)
+}
+
+// NotNil tests a value is nil or not, and it'll failed when the value is nil.
+func (a *Assertion) NotNil(val any, message ...string) error {
+	return NotNil(a.t, val, message...)
+}
+
 // Panic expects the function fn to panic.
 func (a *Assertion) Panic(fn func(), message ...string) (err error) {
 	return Panic(a.t, fn, message...)

equal.go

@@ -31,3 +31,29 @@ func NotDeepEqual(t *testing.T, actual, expect any, message ...string) error {
 
 	return err
 }
+
+// Nil tests a value is nil or not, and it'll failed when the value is not nil.
+func Nil(t *testing.T, val any, message ...string) error {
+	if isNil(val) {
+		return nil
+	}
+
+	err := newAssertionError(fmt.Sprintf("expect nil, got %v", val), message...)
+
+	t.Error(err)
+
+	return err
+}
+
+// NotNil tests a value is nil or not, and it'll failed when the value is nil.
+func NotNil(t *testing.T, val any, message ...string) error {
+	if !isNil(val) {
+		return nil
+	}
+
+	err := newAssertionError("expect not nil, got nil", message...)
+
+	t.Error(err)
+
+	return err
+}

equal_test.go

@@ -45,3 +45,31 @@ func testDeepEqualAndNotDeepEqual(t *testing.T, assertion *Assertion, v1, v2 any
 		t.Errorf("NotEqual(%v, %v) = %v, want = nil", v1, v2, err)
 	}
 }
+
+func TestNilAndNotNil(t *testing.T) {
+	mockT := new(testing.T)
+	assert := New(mockT)
+
+	testNilAndNotNil(t, assert, 1, false)
+	testNilAndNotNil(t, assert, "", false)
+	testNilAndNotNil(t, assert, nil, true)
+	var testAssert *Assertion
+	testNilAndNotNil(t, assert, testAssert, true)
+	testNilAndNotNil(t, assert, assert, false)
+}
+
+func testNilAndNotNil(t *testing.T, assertion *Assertion, v any, isNil bool) {
+	err := assertion.Nil(v)
+	if isNil && err != nil {
+		t.Errorf("Nil(%v) = %v, want nil", v, err)
+	} else if !isNil && err == nil {
+		t.Errorf("Nil(%v) = nil, want error", v)
+	}
+
+	err = assertion.NotNil(v)
+	if isNil && err == nil {
+		t.Errorf("Nil(%v) = nil, want error", v)
+	} else if !isNil && err != nil {
+		t.Errorf("Nil(%v) = %v, want nil", v, err)
+	}
+}