Update MongoDB tests to not fail in Go 1.16

[pcman312]

Go 1.16 introduced changes to the x509.CertPool type that make it incompatible with reflect.DeepEqual (golang/go#45891). This caused some of our tests to start failing in MongoDB. This PR changes the comparison to use github.com/google/go-cmp for the equality check which allows us to ignore certain fields and types.

[Valarissa]

Could we see an output of this error message? Is it expecting no differences and then lists out the differences?

[pcman312]

Note: I flipped the assertion so it has the expected value on the left and the actual on the right.

Here's a failure if I change the expectedOpts in the TestGetTLSAuth/good_ca test to not include the provided cert.Pem:
Updated test case:

"good ca": {
	tlsCAData: cert.Pem,

	expectOpts: options.Client().
		SetTLSConfig(
			&tls.Config{
				RootCAs: x509.NewCertPool(), // <-- Note the missing CA
			},
		),
	expectErr: false,
},

Test output:

$ go test -v -run TestGetTLSAuth/good_ca
=== RUN   TestGetTLSAuth
=== RUN   TestGetTLSAuth/good_ca
    mongodb_test.go:353: assertion failed: values are not equal
        --- expected
        +++ actual
          &options.ClientOptions{
          	... // 22 identical fields
          	ServerSelectionTimeout: nil,
          	SocketTimeout:          nil,
          	TLSConfig: &tls.Config{
          		... // 7 identical fields
          		VerifyPeerCertificate: ⟪0x00⟫,
          		VerifyConnection:      ⟪0x00⟫,
        - 		RootCAs:               nil,
        + 		RootCAs: &x509.CertPool{
        + 			byName:    map[string][]int{"0\x141\x120\x10\x06\x03U\x04\x03\x13\ttest cert": {0}},
        + 			lazyCerts: []x509.lazyCert{{rawSubject: []uint8{...}, getCert: ⟪0x0124c580⟫}},
        + 			haveSum: map[x509.sum224]bool{
        + 				{0xbd, 0x0c, 0xeb, 0xa8, 0xfe, 0xaa, 0xe8, 0xaf, 0x6d, 0xdf, 0xb9, 0x82, 0x58, 0xff, 0x0c, 0x27, 0x3a, 0xbd, 0xd4, 0xba, 0x24, 0x8b, 0x47, 0xef, 0xbc, 0xbc, 0x78, 0xf0}: true,
        + 			},
        + 		},
          		NextProtos: nil,
          		ServerName: "",
          		... // 1 ignored and 16 identical fields
          	},
          	WriteConcern: nil,
          	ZlibLevel:    nil,
          	... // 6 identical fields
          }
--- FAIL: TestGetTLSAuth (0.44s)
    --- FAIL: TestGetTLSAuth/good_ca (0.00s)
FAIL
exit status 1
FAIL	github.com/hashicorp/vault/plugins/database/mongodb	0.881s

Same thing, but messing with the good key test:

"good key": {
	username:   "unittest",
	tlsKeyData: cert.CombinedPEM(),

	expectOpts: options.Client().
		SetTLSConfig(
			&tls.Config{}, // <-- Note the missing cert
		).
		SetAuth(options.Credential{
			AuthMechanism: "MONGODB-X509",
			Username:      "unittest",
		}),
	expectErr: false,
},

Test Output:

$ go test -v -run TestGetTLSAuth/good_key
=== RUN   TestGetTLSAuth
=== RUN   TestGetTLSAuth/good_key
    mongodb_test.go:353: assertion failed: values are not equal
        --- expected
        +++ actual
          &options.ClientOptions{
          	... // 22 identical fields
          	ServerSelectionTimeout: nil,
          	SocketTimeout:          nil,
          	TLSConfig: &tls.Config{
          		Rand:         nil,
          		Time:         ⟪0x00⟫,
        - 		Certificates: nil,
        + 		Certificates: []tls.Certificate{
        + 			{
        + 				Certificate: [][]uint8{{...}},
        + 				PrivateKey: &rsa.PrivateKey{
        + 					PublicKey:   rsa.PublicKey{...},
        + 					D:           s"99111349761763075119885005748638"...,
        + 					Primes:      []*big.Int{...},
        + 					Precomputed: rsa.PrecomputedValues{...},
        + 				},
        + 			},
        + 		},
          		NameToCertificate: nil,
          		GetCertificate:    ⟪0x00⟫,
          		... // 1 ignored and 23 identical fields
          	},
          	WriteConcern: nil,
          	ZlibLevel:    nil,
          	... // 6 identical fields
          }
--- FAIL: TestGetTLSAuth (0.30s)
    --- FAIL: TestGetTLSAuth/good_key (0.00s)
FAIL
exit status 1
FAIL	github.com/hashicorp/vault/plugins/database/mongodb	0.730s

[Valarissa]

Looks good to me, but I'd love to see an example of the error message output!

[Valarissa]

Thanks for that update! Looks great!

[calvn]

Can you remove the extra newline here?