version/info: format: allow more json variants

Allow more variants to yield json output for `podman version` and
`podman info`.  Instead of comparing strings, use a regex and add
unit and e2e tests.

Fixes: #6927
Signed-off-by: Valentin Rothberg <rothberg@redhat.com>

2 files changed, 39 insertions, 0 deletions

diff --git a/cmd/podman/parse/json.go b/cmd/podman/parse/json.go
new file mode 100644
index 000000000..95a6633b8
--- /dev/null
+++ b/cmd/podman/parse/json.go
@@ -0,0 +1,9 @@
+package parse
+
+import "regexp"
+
+var jsonFormatRegex = regexp.MustCompile(`^(\s*json\s*|\s*{{\s*json\s*\.\s*}}\s*)$`)
+
+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
new file mode 100644
index 000000000..5cad185fd
--- /dev/null
+++ b/cmd/podman/parse/json_test.go
@@ -0,0 +1,30 @@
+package parse
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestMatchesJSONFormat(t *testing.T) {
+	tests := []struct {
+		input    string
+		expected bool
+	}{
+		{"json", true},
+		{" json", true},
+		{"json ", true},
+		{"  json   ", true},
+		{"{{json .}}", true},
+		{"{{ json .}}", true},
+		{"{{json .   }}", true},
+		{"  {{  json .    }}   ", true},
+		{"{{json }}", false},
+		{"{{json .", false},
+		{"json . }}", false},
+	}
+
+	for _, tt := range tests {
+		assert.Equal(t, tt.expected, MatchesJSONFormat(tt.input))
+	}
+}