cmd/devp2p, internal/utesting: implement TAP output (#21760)

TAP is a text format for test results. Parsers for it are available in many languages,
making it easy to consume. I want TAP output from our protocol tests because the
Hive wrapper around them needs to know about the test names and their individual
results and logs. It would also be possible to just write this info as JSON, but I don't
want to invent a new format.

This also improves the normal console output for tests (when running without --tap).
It now prints -- RUN lines before any output from the test, and indents the log output
by one space.

cmd/devp2p/discv5cmd.go

@@ -18,13 +18,10 @@ package main
 
 import (
 	"fmt"
-	"os"
 	"time"
 
 	"github.com/ethereum/go-ethereum/cmd/devp2p/internal/v5test"
 	"github.com/ethereum/go-ethereum/common"
-	"github.com/ethereum/go-ethereum/internal/utesting"
-	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/p2p/discover"
 	"gopkg.in/urfave/cli.v1"
 )
@@ -62,7 +59,12 @@ var (
 		Name:   "test",
 		Usage:  "Runs protocol tests against a node",
 		Action: discv5Test,
-		Flags:  []cli.Flag{testPatternFlag, testListen1Flag, testListen2Flag},
+		Flags: []cli.Flag{
+			testPatternFlag,
+			testTAPFlag,
+			testListen1Flag,
+			testListen2Flag,
+		},
 	}
 	discv5ListenCommand = cli.Command{
 		Name:   "listen",
@@ -114,28 +116,14 @@ func discv5Crawl(ctx *cli.Context) error {
 	return nil
 }
 
+// discv5Test runs the protocol test suite.
 func discv5Test(ctx *cli.Context) error {
-	// Disable logging unless explicitly enabled.
-	if !ctx.GlobalIsSet("verbosity") && !ctx.GlobalIsSet("vmodule") {
-		log.Root().SetHandler(log.DiscardHandler())
-	}
-
-	// Filter and run test cases.
 	suite := &v5test.Suite{
 		Dest:    getNodeArg(ctx),
 		Listen1: ctx.String(testListen1Flag.Name),
 		Listen2: ctx.String(testListen2Flag.Name),
 	}
-	tests := suite.AllTests()
-	if ctx.IsSet(testPatternFlag.Name) {
-		tests = utesting.MatchTests(tests, ctx.String(testPatternFlag.Name))
-	}
-	results := utesting.RunTests(tests, os.Stdout)
-	if fails := utesting.CountFailures(results); fails > 0 {
-		return fmt.Errorf("%v/%v tests passed.", len(tests)-fails, len(tests))
-	}
-	fmt.Printf("%v/%v passed\n", len(tests), len(tests))
-	return nil
+	return runTests(ctx, suite.AllTests())
 }
 
 func discv5Listen(ctx *cli.Context) error {