cmd/runtimetest/main: Use TAP diagnostics for errors

This lets us print SHOULD violations even if they're non-fatal.  It
also gets us back to consumable TAP output.  I added a /foo entry to
defaultFS for testing, and before this commit:

  $ ./runtimetest
  TAP version 13
  not ok 1 - root filesystem
  ok 2 - hostname
  not ok 3 - process
  not ok 4 - mounts
  not ok 5 - user
  ok 6 - rlimits
  ok 7 - capabilities
  ok 8 - default symlinks
  ok 9 - default file system
  ok 10 - default devices
  ok 11 - linux devices
  not ok 12 - linux process
  ok 13 - masked paths
  ok 14 - oom score adj
  ok 15 - read only paths
  ok 16 - rootfs propagation
  ok 17 - sysctls
  ok 18 - uid mappings
  ok 19 - gid mappings
  1..19
  6 errors occurred:

  * rootfs must not be readonly
  Refer to: https://github.com/opencontainers/runtime-spec/blob/v1.0.0/config.md#root
  * Cwd expected: /, actual: /home/wking/.local/lib/go/src/github.com/opencontainers/runtime-tools
  * mounts[1] {/tmp tmpfs none []} does not exist
  Refer to: https://github.com/opencontainers/runtime-spec/blob/v1.0.0/config.md#mounts
  * mounts[2] {/dev devtmpfs devtmpfs []} mounted before mounts[0] {/tmp tmpfs none []}
  Refer to: https://github.com/opencontainers/runtime-spec/blob/v1.0.0/config.md#mounts
  * UID expected: 1, actual: 1000
  * Process arguments expected: ./runtimetest, actual: sh
  $ echo $?
  1

The TAP 13 spec doesn't cover script exit-code handling [1], but that
exit code confuses prove unless you set --ignore-exit:

  $ prove ./runtimetest
  ./runtimetest .. 1/? 6 errors occurred:

  * rootfs must not be readonly
  Refer to: https://github.com/opencontainers/runtime-spec/blob/v1.0.0/config.md#root
  * Cwd expected: /, actual: /home/wking/.local/lib/go/src/github.com/opencontainers/runtime-tools
  * mounts[1] {/tmp tmpfs none []} does not exist
  Refer to: https://github.com/opencontainers/runtime-spec/blob/v1.0.0/config.md#mounts
  * mounts[2] {/dev devtmpfs devtmpfs []} mounted before mounts[0] {/tmp tmpfs none []}
  Refer to: https://github.com/opencontainers/runtime-spec/blob/v1.0.0/config.md#mounts
  * UID expected: 1, actual: 1000
  * Process arguments expected: ./runtimetest, actual: sh
  ./runtimetest .. Dubious, test returned 1 (wstat 256, 0x100)
  Failed 5/19 subtests

  Test Summary Report
  -------------------
  ./runtimetest (Wstat: 256 Tests: 19 Failed: 5)
    Failed tests:  1, 3-5, 12
    Non-zero exit status: 1
  Files=1, Tests=19,  0 wallclock secs ( 0.02 usr +  0.00 sys =  0.02 CPU)
  Result: FAIL

Note the "Dubious, test returned 1".  And with the diagnostics written
to stderr, there's no way to have prove catch that.

With this commit, we're back to TAP-compatible output and exit codes,
using TAP's diagnostics [2] to share the failure details.

  $ ./runtimetest
  TAP version 13
  not ok 1 - root filesystem
  # rootfs must not be readonly
  # Refer to: https://github.com/opencontainers/runtime-spec/blob/v1.0.0/config.md#root
  ok 2 - hostname
  not ok 3 - process
  # Cwd expected: /, actual: /home/wking/.local/lib/go/src/github.com/opencontainers/runtime-tools
  not ok 4 - mounts
  # mounts[1] {/tmp tmpfs none []} does not exist
  # Refer to: https://github.com/opencontainers/runtime-spec/blob/v1.0.0/config.md#mounts
  not ok 5 - mounts
  # mounts[2] {/dev devtmpfs devtmpfs []} mounted before mounts[0] {/tmp tmpfs none []}
  # Refer to: https://github.com/opencontainers/runtime-spec/blob/v1.0.0/config.md#mounts
  not ok 6 - user
  # UID expected: 1, actual: 1000
  ok 7 - rlimits
  ok 8 - capabilities
  ok 9 - default symlinks
  ok 10 - default file system
  ok 11 - default devices
  ok 12 - linux devices
  not ok 13 - linux process
  # Process arguments expected: ./runtimetest, actual: sh
  ok 14 - masked paths
  ok 15 - oom score adj
  ok 16 - read only paths
  ok 17 - rootfs propagation
  ok 18 - sysctls
  ok 19 - uid mappings
  ok 20 - gid mappings
  1..20
  $ echo $?
  0

You can use prove without --ignore-edit to summarize:

  $ prove ./runtimetest
  ./runtimetest .. Failed 6/20 subtests

  Test Summary Report
  -------------------
  ./runtimetest (Wstat: 0 Tests: 20 Failed: 6)
    Failed tests:  1, 3-6, 13
  Files=1, Tests=20,  0 wallclock secs ( 0.03 usr +  0.00 sys =  0.03 CPU)
  Result: FAIL

And prove knows that the tests failed from TAP, with the script exit
code saying "we were able to run the tests" and not speaking to
pass/fail:

  $ echo $?
  1

If that's too compact, you can ask prove to show failures and
comments:

  $ prove -fo ./runtimetest
  ./runtimetest .. 1/?
  not ok 1 - root filesystem
  # rootfs must not be readonly
  # Refer to: https://github.com/opencontainers/runtime-spec/blob/v1.0.0/config.md#root
  not ok 3 - process
  # Cwd expected: /, actual: /home/wking/.local/lib/go/src/github.com/opencontainers/runtime-tools
  not ok 4 - mounts
  # mounts[1] {/tmp tmpfs none []} does not exist
  # Refer to: https://github.com/opencontainers/runtime-spec/blob/v1.0.0/config.md#mounts
  not ok 5 - mounts
  # mounts[2] {/dev devtmpfs devtmpfs []} mounted before mounts[0] {/tmp tmpfs none []}
  # Refer to: https://github.com/opencontainers/runtime-spec/blob/v1.0.0/config.md#mounts
  not ok 6 - user
  # UID expected: 1, actual: 1000
  not ok 13 - linux process
  # Process arguments expected: ./runtimetest, actual: sh
  ./runtimetest .. Failed 6/20 subtests

  Test Summary Report
  -------------------
  ./runtimetest (Wstat: 0 Tests: 20 Failed: 6)
    Failed tests:  1, 3-6, 13
  Files=1, Tests=20,  0 wallclock secs ( 0.03 usr +  0.00 sys =  0.03 CPU)
  Result: FAIL

You can also turn that SHOULD error into a failure by cranking up the
compliance level:

  $ prove -fo ./runtimetest :: --compliance-level SHOULD

although I don't have any interesting SHOULD violations between my
test config.json and my host system.

[1]: https://testanything.org/tap-version-13-specification.html#todo
[2]: https://testanything.org/tap-version-13-specification.html#diagnostics

Signed-off-by: W. Trevor King <wking@tremily.us>

cmd/runtimetest/main.go

@@ -891,46 +891,43 @@ func run(context *cli.Context) error {
 		complianceLevel = rfc2119.Must
 		logrus.Warningf("%s, using 'MUST' by default.", err.Error())
 	}
-	var validationErrors error
-	for _, v := range defaultValidations {
-		err := v.test(spec)
-		t.Ok(err == nil, v.description)
-		if err != nil {
-			if e, ok := err.(*specerror.Error); ok && e.Err.Level < complianceLevel {
-				continue
-			}
-			validationErrors = multierror.Append(validationErrors, err)
-		}
-	}
 
-	if platform == "linux" || platform == "solaris" {
-		for _, v := range posixValidations {
-			err := v.test(spec)
-			t.Ok(err == nil, v.description)
-			if err != nil {
-				if e, ok := err.(*specerror.Error); ok && e.Err.Level < complianceLevel {
-					continue
-				}
-				validationErrors = multierror.Append(validationErrors, err)
-			}
-		}
+	validations := defaultValidations
+	if platform == "linux" {
+		validations = append(validations, posixValidations...)
+		validations = append(validations, linuxValidations...)
+	} else if platform == "solaris" {
+		validations = append(validations, posixValidations...)
 	}
 
-	if platform == "linux" {
-		for _, v := range linuxValidations {
-			err := v.test(spec)
-			t.Ok(err == nil, v.description)
-			if err != nil {
-				if e, ok := err.(*specerror.Error); ok && e.Err.Level < complianceLevel {
-					continue
+	for _, v := range validations {
+		err := v.test(spec)
+		if err == nil {
+			t.Pass(v.description)
+		} else {
+			merr, ok := err.(*multierror.Error)
+			if ok {
+				for _, err = range merr.Errors {
+					if e, ok := err.(*rfc2119.Error); ok {
+						t.Ok(e.Level < complianceLevel, v.description)
+					} else {
+						t.Fail(v.description)
+					}
+					t.Diagnostic(err.Error())
+				}
+			} else {
+				if e, ok := err.(*rfc2119.Error); ok {
+					t.Ok(e.Level < complianceLevel, v.description)
+				} else {
+					t.Fail(v.description)
 				}
-				validationErrors = multierror.Append(validationErrors, err)
+				t.Diagnostic(err.Error())
 			}
 		}
 	}
 	t.AutoPlan()
 
-	return validationErrors
+	return nil
 }
 
 func main() {