test: Improve layout of helper binaries

This patch moves the test helper binaries to a "one directory per
helper" layout, and also makes them to be ignored in the coverage build
instead of all builds.

With this change, "go build ./..." will build all binaries including the
test helpers, which helps make sure that module manage automation also
considers them. In particular, this makes "go mod tidy" work fine.

test/util/conngen/conngen.go

@@ -1,5 +1,5 @@
-//go:build ignore
-// +build ignore
+//go:build !coverage
+// +build !coverage
 
 // SMTP connection generator, for testing purposes.
 package main

test/util/coverhtml/coverhtml.go

@@ -1,5 +1,5 @@
-//go:build ignore
-// +build ignore
+//go:build !coverage
+// +build !coverage
 
 // Generate an HTML visualization of a Go coverage profile.
 // Serves a similar purpose to "go tool cover -html", but has a different

test/util/fexp/fexp.go

@@ -1,5 +1,5 @@
-//go:build ignore
-// +build ignore
+//go:build !coverage
+// +build !coverage
 
 // Fetch an URL, and check if the response matches what we expect.
 //

test/util/generate_cert/generate_cert.go

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build ignore
-// +build ignore
+//go:build !coverage
+// +build !coverage
 
 // Generate a self-signed X.509 certificate for a TLS server. Outputs to
 // 'cert.pem' and 'key.pem' and will overwrite existing files.

test/util/gocovcat/gocovcat.go

@@ -2,8 +2,8 @@
 //
 // From: https://git.lukeshu.com/go/cmd/gocovcat/
 //
-//go:build ignore
-// +build ignore
+//go:build !coverage
+// +build !coverage
 
 // Copyright 2017 Luke Shumaker <lukeshu@parabola.nu>
 //

test/util/lib.sh

@@ -101,26 +101,29 @@ function chamuyero() {
 }
 
 function generate_cert() {
-	go run ${UTILDIR}/generate_cert.go "$@"
+	( cd ${UTILDIR}/generate_cert/; go build )
+	${UTILDIR}/generate_cert/generate_cert "$@"
 }
 
 function loadgen() {
-	go run ${UTILDIR}/loadgen.go "$@"
+	( cd ${UTILDIR}/loadgen/; go build )
+	${UTILDIR}/loadgen/loadgen "$@"
 }
 
 function conngen() {
-	go run ${UTILDIR}/conngen.go "$@"
+	( cd ${UTILDIR}/conngen/; go build )
+	${UTILDIR}/conngen/conngen "$@"
 }
 
 function minidns_bg() {
-	( cd ${UTILDIR}; go build minidns.go )
-	${UTILDIR}/minidns "$@" &
+	( cd ${UTILDIR}/minidns; go build )
+	${UTILDIR}/minidns/minidns "$@" &
 	MINIDNS=$!
 }
 
 function fexp() {
-	( cd ${UTILDIR}; go build fexp.go )
-	${UTILDIR}/fexp "$@"
+	( cd ${UTILDIR}/fexp/; go build )
+	${UTILDIR}/fexp/fexp "$@"
 }
 
 function timeout() {

test/util/loadgen/loadgen.go

@@ -1,5 +1,5 @@
-//go:build ignore
-// +build ignore
+//go:build !coverage
+// +build !coverage
 
 // SMTP load generator, for testing purposes.
 package main

test/util/minidns/minidns.go

@@ -1,5 +1,5 @@
-//go:build ignore
-// +build ignore
+//go:build !coverage
+// +build !coverage
 
 // minidns is a trivial DNS server used for testing.
 //