testapp: Clear PresentmentModel before using MdocProximityQrPresentment. (#1311)

Also add guidance in the KDoc and log a warning if this isn't done.

Fixes #1306.

Test: Manually tested.

Signed-off-by: David Zeuthen <[email protected]>

Author: davidz25

multipaz-compose/src/commonMain/kotlin/org/multipaz/compose/presentment/MdocProximityQrPresentment.kt

@@ -28,8 +28,11 @@ import org.multipaz.models.presentment.MdocPresentmentMechanism
 import org.multipaz.models.presentment.PresentmentModel
 import org.multipaz.models.presentment.PresentmentSource
 import org.multipaz.prompt.PromptModel
+import org.multipaz.util.Logger
 import org.multipaz.util.toBase64Url
 
+private const val TAG = "MdocProximityQrPresentment"
+
 /**
  * A composable for presentment with QR engagement according to ISO/IEC 18013-5:2021.
  *
@@ -45,6 +48,9 @@ import org.multipaz.util.toBase64Url
  *   includes showing consent and authentication dialogs. When the reader disconnects [presentmentModel]
  *   goes to state [PresentmentModel.State.IDLE] and [showQrButton] composable is shown.
  *
+ * Applications should call [PresentmentModel.reset] before entering the composition containing this
+ * composable.
+ *
  * @param modifier a [Modifier].
  * @param appName the name of the application.
  * @param appIconPainter the icon for the application.
@@ -123,6 +129,10 @@ fun MdocProximityQrPresentment(
             }
 
             PresentmentModel.State.CONNECTING -> {
+                if (qrCodeToShow.value == null) {
+                    Logger.w(TAG, "No QR code. Did you forget to reset the PresentmentModel before " +
+                            "entering the composition containing this MdocProximityQrPresentment?")
+                }
                 qrCodeToShow.value?.let {
                     showQrCode(it)
                 }

samples/testapp/src/commonMain/kotlin/org/multipaz/testapp/App.kt

@@ -886,7 +886,10 @@ class App private constructor (val promptModel: PromptModel) {
                             onClickConsentSheetList = { navController.navigate(ConsentPromptDestination.route) },
                             onClickQrCodes = { navController.navigate(QrCodesDestination.route) },
                             onClickNfc = { navController.navigate(NfcDestination.route) },
-                            onClickIsoMdocProximitySharing = { navController.navigate(IsoMdocProximitySharingDestination.route) },
+                            onClickIsoMdocProximitySharing = {
+                                presentmentModel.reset()
+                                navController.navigate(IsoMdocProximitySharingDestination.route)
+                            },
                             onClickIsoMdocProximityReading = { navController.navigate(IsoMdocProximityReadingDestination.route) },
                             onClickDcRequest = { navController.navigate(DcRequestDestination.route) },
                             onClickMdocTransportMultiDeviceTesting = { navController.navigate(IsoMdocMultiDeviceTestingDestination.route) },