Add PreparedRun model and render formatters (text/json) with tests

internal/format/prepared_run_test.go

@@ -0,0 +1,41 @@
+package format
+
+import (
+	"errors"
+	"testing"
+)
+
+func TestParsePreparedRunOutputFormatRecognizesSupportedNames(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		want  PreparedRunOutputFormat
+	}{
+		{name: "default empty", input: "", want: DefaultPreparedRunOutputFormat},
+		{name: "text", input: "text", want: PreparedRunFormatText},
+		{name: "json", input: "json", want: PreparedRunFormatJSON},
+		{name: "trim and case", input: "  JSON  ", want: PreparedRunFormatJSON},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			got, err := ParsePreparedRunOutputFormat(tc.input)
+			if err != nil {
+				t.Fatalf("expected no error, got %v", err)
+			}
+			if got != tc.want {
+				t.Fatalf("expected %q, got %q", tc.want, got)
+			}
+		})
+	}
+}
+
+func TestParsePreparedRunOutputFormatUnknownFails(t *testing.T) {
+	_, err := ParsePreparedRunOutputFormat("yaml")
+	if err == nil {
+		t.Fatal("expected error for unknown format")
+	}
+	if !errors.Is(err, ErrUnknownPreparedRunFormat) {
+		t.Fatalf("expected ErrUnknownPreparedRunFormat, got %v", err)
+	}
+}