System tests: various fixes

- zstd test - give unique name.

   a36d81c copy/pasted an existing test but didn't give
   the new test a new name, leading to bats warning:
      duplicate test name(s) in [...]/020-copy.bats

 - start_registry() - use bash builtins, not curl, to test
   if registry port is open.

   curl on Fedora now barfs with "Received HTTP/0.9 when not
   allowed" when the registry is run with SSL, because the
   response is not valid HTTP. One workaround would be 'curl
   --http0.9' but (surprise) that option doesn't exist on rhel8;
   and even with that option we would need --output /dev/null
   to silence a different curl warning. Curl is overkill
   for this purpose anyway, all we really need is netcat
   or some simple binary is-port-listening-or-not test.
   Fortunately, bash provides a /dev/tcp/<host>/<port>
   emulator that does the right thing and works on Fedora
   as well as RHEL8.

 - new log_and_run() helper

   This is the noisiest yet least critical part of this PR.
   I'm sorry. It's motivated by my frustration in trying
   to reproduce the curl problem above: getting just the
   right incantation of openssl + podman-run cost me time.
   With this enhancement, important commands are logged
   as part of the output of failing tests, making it
   easy[*] for maintenance programmers to figure out a
   recipe for reproducing the failure.

     [*] "easy" as long as the test-writing developer
         uses log_and_run() wisely.

Signed-off-by: Ed Santiago <santiago@redhat.com>

systemtest/020-copy.bats

@@ -45,7 +45,7 @@ function setup() {
 }
 
 # Compression zstd
-@test "copy: oci, round trip" {
+@test "copy: oci, round trip, zstd" {
     local remote_image=docker://busybox:latest
 
     local dir=$TESTDIR/dir

systemtest/helpers.bash

@@ -106,6 +106,23 @@ function run_skopeo() {
     fi
 }
 
+#################
+#  log_and_run  #  log a command for later debugging, then run it
+#################
+#
+# When diagnosing a test failure,  it can be really nice to see the
+# more important commands that have been run in test setup: openssl,
+# podman registry, other complex commands that can give one a boost
+# when trying to reproduce problems. This simple wrapper takes a
+# command as its arg, echoes it to stdout (with a '$' prefix),
+# then runs the command. BATS does not show stdout unless there's
+# an error. Use this judiciously.
+#
+function log_and_run() {
+    echo "\$ $*"
+    "$@"
+}
+
 #########
 #  die  #  Abort with helpful message
 #########
@@ -282,7 +299,7 @@ start_registry() {
         fi
 
         if ! egrep -q "^$testuser:" $AUTHDIR/htpasswd; then
-            $PODMAN run --rm --entrypoint htpasswd registry:2 \
+            log_and_run $PODMAN run --rm --entrypoint htpasswd registry:2 \
                    -Bbn $testuser $testpassword >> $AUTHDIR/htpasswd
         fi
 
@@ -297,7 +314,7 @@ start_registry() {
     if [[ -n $create_cert ]]; then
         CERT=$AUTHDIR/domain.crt
         if [ ! -e $CERT ]; then
-            openssl req -newkey rsa:4096 -nodes -sha256 \
+            log_and_run openssl req -newkey rsa:4096 -nodes -sha256 \
                     -keyout $AUTHDIR/domain.key -x509 -days 2 \
                     -out $CERT \
                     -subj "/C=US/ST=Foo/L=Bar/O=Red Hat, Inc./CN=localhost"
@@ -312,15 +329,15 @@ start_registry() {
         # test the client. (If client sees a matching .key file, it fails)
         # Thanks to Miloslav Trmac for this hint.
         mkdir -p $TESTDIR/client-auth
-        cp $CERT $TESTDIR/client-auth/
+        log_and_run cp $CERT $TESTDIR/client-auth/
     fi
 
-    $PODMAN run -d --name $name "${reg_args[@]}" registry:2
+    log_and_run $PODMAN run -d --name $name "${reg_args[@]}" registry:2
 
     # Wait for registry to actually come up
     timeout=10
     while [[ $timeout -ge 1 ]]; do
-        if curl localhost:$port/; then
+        if echo -n >/dev/tcp/127.0.0.1/$port; then
             return
         fi