detect and report invalid field names

[pohly]

I was experimenting with what happens when I use HaveField with a field name that doesn't exist:

			gomega.Eventually(getNewCalls).WithTimeout(registrationTimeout).Should(gomega.HaveExactElements(
				gomega.And(
					gomega.HaveField("FullMethod", "/pluginregistration.Registration/GetInfo"),
					gomega.HaveField("Err", gomega.BeNil()),
				),
				gomega.And(
					gomega.HaveField("FullMethod", "/pluginregistration.Registration/NotifyRegistrationStatus"),
					gomega.HaveField("Err2", gomega.BeNil()),
				),
			), "kubelet plugin should be registered via two calls, GetInfo and NotifyRegistrationStatus")

getNewCalls returns a slice of

type GRPCCall struct {
	FullMethod string
	Request interface{}
	Response interface{}
	Err error
}

I expected to get some failure message pointing out that there is no Err2 field (Err is correct).

Instead I got:

 [PANICKED] Test Panicked
  In [It] at: vendor/github.com/onsi/gomega/internal/async_assertion.go:370 @ 05/31/23 15:00:16.881

  runtime error: invalid memory address or nil pointer dereference

  Full Stack Trace
    k8s.io/kubernetes/vendor/github.com/onsi/gomega/internal.(*AsyncAssertion).pollMatcher.func1()
    	vendor/github.com/onsi/gomega/internal/async_assertion.go:370 +0x98
    panic({0x4986fa0, 0x86e82a0})
    	/nvme/gopath/src/k8s.io/kubernetes/_output/local/.gimme/versions/go1.20.4.linux.amd64/src/runtime/panic.go:884 +0x213
    k8s.io/kubernetes/vendor/github.com/onsi/gomega/matchers.(*HaveFieldMatcher).FailureMessage(0xc0003e8940, {0xc00052f090?, 0xc001b5aad0?})
    	vendor/github.com/onsi/gomega/matchers/have_field.go:89 +0x7c
    k8s.io/kubernetes/vendor/github.com/onsi/gomega/matchers.(*AndMatcher).FailureMessage(0xc001b5aab0?, {0x4df10e0?, 0xc000afa140?})
    	vendor/github.com/onsi/gomega/matchers/and.go:30 +0x2c
    k8s.io/kubernetes/vendor/github.com/onsi/gomega/matchers.(*HaveExactElementsMatcher).Match(0xc0003e8980, {0x4582de0, 0xc000908558})
    	vendor/github.com/onsi/gomega/matchers/have_exact_elements.go:50 +0x1e2
    k8s.io/kubernetes/vendor/github.com/onsi/gomega/internal.(*AsyncAssertion).pollMatcher(0xc001ad3dd0?, {0x5bf8800?, 0xc0003e8980?}, {0x4582de0?, 0xc000908558?})
    	vendor/github.com/onsi/gomega/internal/async_assertion.go:375 +0x82
    k8s.io/kubernetes/vendor/github.com/onsi/gomega/internal.(*AsyncAssertion).match(0xc0018ce4d0, {0x5bf8800?, 0xc0003e8980}, 0x1, {0xc0016de420, 0x1, 0x1})
    	vendor/github.com/onsi/gomega/internal/async_assertion.go:550 +0xb15
    k8s.io/kubernetes/vendor/github.com/onsi/gomega/internal.(*AsyncAssertion).Should(0xc0018ce4d0, {0x5bf8800, 0xc0003e8980}, {0xc0016de420, 0x1, 0x1})
    	vendor/github.com/onsi/gomega/internal/async_assertion.go:145 +0x8d
    k8s.io/kubernetes/test/e2e_node.glob..func15.1.2({0x0?, 0x0?})
    	test/e2e_node/dra_test.go:74 +0x4a3

[onsi]

ah good catch. looks like an issue in HaveExactElements - it's calling FailureMessage on HaveField when it should instead be reporting the error returned by HaveField.

https://github.com/onsi/gomega/blob/99a29d5128d6fd87bad628e94d1cf92e82dc2b32/matchers/have_exact_elements.go#LL50C1-L50C1

i'll need to fix it...

[onsi]

I've fixed HaveExactElement and released 1.27.8- this should be working correctly now. Please reopen the issue if you're still having trouble with it.