stats: list all running containers unless specified otherwise

Unless specified otherwise by --all, --latest or via arguments, list all
running containers.  This matches the behaviour of Docker and is also
illustrated in the man pages where containers and options are marked to
be optional.

Fixes: #4274
Signed-off-by: Valentin Rothberg <rothberg@redhat.com>

test/e2e/stats_test.go

@@ -11,6 +11,8 @@ import (
 	. "github.com/onsi/gomega"
 )
 
+// TODO: we need to check the output. Currently, we only check the exit codes
+// which is not enough.
 var _ = Describe("Podman stats", func() {
 	var (
 		tempdir    string
@@ -61,6 +63,15 @@ var _ = Describe("Podman stats", func() {
 		Expect(session.ExitCode()).To(Equal(0))
 	})
 
+	It("podman stats on all running containers", func() {
+		session := podmanTest.RunTopContainer("")
+		session.WaitWithDefaultTimeout()
+		Expect(session.ExitCode()).To(Equal(0))
+		session = podmanTest.Podman([]string{"stats", "--no-stream"})
+		session.WaitWithDefaultTimeout()
+		Expect(session.ExitCode()).To(Equal(0))
+	})
+
 	It("podman stats only output cids", func() {
 		session := podmanTest.RunTopContainer("")
 		session.WaitWithDefaultTimeout()

test/system/015-help.bats

@@ -55,9 +55,11 @@ function check_help() {
 
         # If usage has required arguments, try running without them
         if expr "$usage" : '.*\[flags\] [A-Z]' >/dev/null; then
-            dprint "podman $@ $cmd (without required args)"
-            run_podman 125 "$@" $cmd
-            is "$output" "Error:"
+            if [ "$cmd" != "stats"]; then
+                dprint "podman $@ $cmd (without required args)"
+                run_podman 125 "$@" $cmd
+                is "$output" "Error:"
+            fi
         fi
 
         count=$(expr $count + 1)