Restore "table" --format from V1

* --format "table {{.field..." will print fields out in a table with
  headings.  Table keyword is removed, spaces between fields are
  converted to tabs
* Update parse.MatchesJSONFormat()'s regex to be more inclusive
* Add report.Headers(), obtain all the field names to be used as
  column headers, a map of field name to column headers may be provided
  to override the field names
* Update several commands to use new functions

Signed-off-by: Jhon Honce <jhonce@redhat.com>

2 files changed, 22 insertions, 6 deletions

diff --git a/cmd/podman/parse/json.go b/cmd/podman/parse/json.go
index 95a6633b8..40ac415db 100644
--- a/cmd/podman/parse/json.go
+++ b/cmd/podman/parse/json.go
@@ -2,8 +2,9 @@ package parse
 
 import "regexp"
 
-var jsonFormatRegex = regexp.MustCompile(`^(\s*json\s*|\s*{{\s*json\s*\.\s*}}\s*)$`)
+var jsonFormatRegex = regexp.MustCompile(`^\s*(json|{{\s*json\s*( \.)?\s*}})\s*$`)
 
+// MatchesJSONFormat test CLI --format string to be a JSON request
 func MatchesJSONFormat(s string) bool {
 	return jsonFormatRegex.Match([]byte(s))
 }
diff --git a/cmd/podman/parse/json_test.go b/cmd/podman/parse/json_test.go
index 5cad185fd..ec3b5664b 100644
--- a/cmd/podman/parse/json_test.go
+++ b/cmd/podman/parse/json_test.go
@@ -1,6 +1,8 @@
 package parse
 
 import (
+	"fmt"
+	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -13,18 +15,31 @@ func TestMatchesJSONFormat(t *testing.T) {
 	}{
 		{"json", true},
 		{" json", true},
-		{"json ", true},
+		{" json ", true},
 		{"  json   ", true},
+		{"{{json}}", true},
+		{"{{json }}", true},
 		{"{{json .}}", true},
 		{"{{ json .}}", true},
-		{"{{json .   }}", true},
-		{"  {{  json .    }}   ", true},
-		{"{{json }}", false},
-		{"{{json .", false},
+		{"{{ json . }}", true},
+		{"  {{   json   .  }}  ", true},
+		{"{{ json .", false},
 		{"json . }}", false},
+		{"{{.ID }} json .", false},
+		{"json .", false},
+		{"{{json.}}", false},
 	}
 
 	for _, tt := range tests {
 		assert.Equal(t, tt.expected, MatchesJSONFormat(tt.input))
 	}
+
+	for _, tc := range tests {
+		tc := tc
+		label := "MatchesJSONFormat/" + strings.ReplaceAll(tc.input, " ", "_")
+		t.Run(label, func(t *testing.T) {
+			t.Parallel()
+			assert.Equal(t, tc.expected, MatchesJSONFormat(tc.input), fmt.Sprintf("Scanning %q failed", tc.input))
+		})
+	}
 }