feat: ✨ make nil ErrorAssertion a valid option (#40)

errorassertion.go

@@ -1,7 +1,10 @@
 package errassert
 
-// ErrorAssertion represents single single instance of the error assertion.
+// ErrorAssertion represents a single instance of the error assertion.
 // If the error is not as expected, call returns an error.
+//
+// Zero value (nil) is valid and Assert nor Require will never fail. It can be looked at as
+// "I don't care about the error" assertion.
 type ErrorAssertion func(error) error
 
 // TestingT defines the subset of testing.TB methods used by errassert.
@@ -14,6 +17,10 @@ type TestingT interface {
 
 // Assert checks if the error is as expected and calls t.Fail if not.
 func (assertion ErrorAssertion) Assert(t TestingT, err error) {
+	if assertion == nil {
+		return
+	}
+
 	t.Helper()
 	if tErr := assertion(err); tErr != nil {
 		t.Log(tErr.Error())
@@ -23,6 +30,10 @@ func (assertion ErrorAssertion) Assert(t TestingT, err error) {
 
 // Require checks if the error is as expected and calls t.FailNow if not.
 func (assertion ErrorAssertion) Require(t TestingT, err error) {
+	if assertion == nil {
+		return
+	}
+
 	t.Helper()
 	if tErr := assertion(err); tErr != nil {
 		t.Log(tErr.Error())

errorassertion_test.go

@@ -66,6 +66,21 @@ func TestErrorAssertion_Require_Fail(t *testing.T) {
 	mockT.AssertLogfCalledWith(t, failMsg)
 }
 
+func TestErrorAssertion_NilFunctional(t *testing.T) {
+	// Given
+	mockT := NewMockT()
+	var assertion errassert.ErrorAssertion
+
+	// When
+	assertion.Assert(mockT, anError)
+	assertion.Require(mockT, anError)
+
+	// Then
+	mockT.AssertNotFailed(t)
+	mockT.AssertNotFailedNow(t)
+	mockT.AssertLogfNotCalled(t)
+}
+
 func passAssertion(error) error {
 	return nil
 }