Add system test for shell completion

There exists a unit test to ensure that shell completion functions are
defined. However there was no check about the quality of the provided
shell completions. Lets change that.

The idea is to create a general test that makes sure we are suggesting
containers,pods,images... for the correct commands. This works by
reading the command use line and checking for each arg if we provide
the correct suggestions for this arg.

It includes the following tests:
- flag suggestions if [options] is set
- container, pod, image, network, volume, registry completion
- path completion for the appropriate arg KEYWORDS (`PATH`,`CONTEXT`,etc.)
- no completion if there are no args
- completion for more than one arg if it ends with `...]`

The test does not cover completion values for flags and not every arg KEYWORD
is supported. This is still a huge improvement and covers most use cases.

This test spotted several inconsistencies between the completion and the
command use line. All of them have been adjusted to make the test pass.

The biggest advantage is that the completions always match the latest
command changes. So if someone changes the arguments for a command this
ensures that the completions must be adjusted.

Signed-off-by: Paul Holzinger <paul.holzinger@web.de>

2 files changed, 3 insertions, 2 deletions

diff --git a/cmd/podman/system/service.go b/cmd/podman/system/service.go
index 42482b5d9..f8bdbfa10 100644
--- a/cmd/podman/system/service.go
+++ b/cmd/podman/system/service.go
@@ -10,6 +10,7 @@ import (
 	"time"
 
 	"github.com/containers/common/pkg/completion"
+	"github.com/containers/podman/v2/cmd/podman/common"
 	"github.com/containers/podman/v2/cmd/podman/registry"
 	"github.com/containers/podman/v2/pkg/domain/entities"
 	"github.com/containers/podman/v2/pkg/rootless"
@@ -32,7 +33,7 @@ Enable a listening service for API access to Podman commands.
 		Short:             "Run API service",
 		Long:              srvDescription,
 		RunE:              service,
-		ValidArgsFunction: completion.AutocompleteDefault,
+		ValidArgsFunction: common.AutocompleteDefaultOneArg,
 		Example:           `podman system service --time=0 unix:///tmp/podman.sock`,
 	}
 
diff --git a/cmd/podman/system/unshare.go b/cmd/podman/system/unshare.go
index 437cf7b2e..364852979 100644
--- a/cmd/podman/system/unshare.go
+++ b/cmd/podman/system/unshare.go
@@ -14,7 +14,7 @@ import (
 var (
 	unshareDescription = "Runs a command in a modified user namespace."
 	unshareCommand     = &cobra.Command{
-		Use:                   "unshare [COMMAND [ARG ...]]",
+		Use:                   "unshare [COMMAND [ARG...]]",
 		DisableFlagsInUseLine: true,
 		Short:                 "Run a command in a modified user namespace",
 		Long:                  unshareDescription,