Fix test_hotspot_upstream_cellular failure

This change:
  1. Move precondition checks prior to setup hotspot.
     This removes the need of redundant clean-up if
     the device doesn't meet preconditions.
  2. Use unregisterAll instead of unregisterCell to
     clean-up registered connections to prevent from
     complex error handling in clean-up stage.

Test: m connectivity_multi_devices_snippet && \
      atest CtsConnectivityMultiDevicesTestCases:ConnectivityMultiDevicesTest
Fix: 345110845
Change-Id: I4de0e7401d52f891948eb7b5a8c112a837cb0c3e
diff --git a/tests/cts/multidevices/connectivity_multi_devices_test.py b/tests/cts/multidevices/connectivity_multi_devices_test.py
index 417db99..1d6fb51 100644
--- a/tests/cts/multidevices/connectivity_multi_devices_test.py
+++ b/tests/cts/multidevices/connectivity_multi_devices_test.py
@@ -34,6 +34,9 @@
     )
 
   def test_hotspot_upstream_wifi(self):
+    tether_utils.assume_hotspot_test_preconditions(
+        self.serverDevice, self.clientDevice, UpstreamType.WIFI
+    )
     try:
       # Connectivity of the client verified by asserting the validated capability.
       tether_utils.setup_hotspot_and_client_for_upstream_type(
@@ -45,6 +48,9 @@
       )
 
   def test_hotspot_upstream_cellular(self):
+    tether_utils.assume_hotspot_test_preconditions(
+        self.serverDevice, self.clientDevice, UpstreamType.CELLULAR
+    )
     try:
       # Connectivity of the client verified by asserting the validated capability.
       tether_utils.setup_hotspot_and_client_for_upstream_type(
diff --git a/tests/cts/multidevices/snippet/ConnectivityMultiDevicesSnippet.kt b/tests/cts/multidevices/snippet/ConnectivityMultiDevicesSnippet.kt
index 8805edd..f4ad2c4 100644
--- a/tests/cts/multidevices/snippet/ConnectivityMultiDevicesSnippet.kt
+++ b/tests/cts/multidevices/snippet/ConnectivityMultiDevicesSnippet.kt
@@ -77,9 +77,9 @@
         ctsNetUtils.expectNetworkIsSystemDefault(network)
     }
 
-    @Rpc(description = "Unrequest cellular connection.")
-    fun unrequestCellular() {
-        cbHelper.unrequestCell()
+    @Rpc(description = "Unregister all connections.")
+    fun unregisterAll() {
+        cbHelper.unregisterAll()
     }
 
     @Rpc(description = "Ensure any wifi is connected and is the default network.")
diff --git a/tests/cts/multidevices/tether_utils.py b/tests/cts/multidevices/tether_utils.py
index a2d703c..61f5c43 100644
--- a/tests/cts/multidevices/tether_utils.py
+++ b/tests/cts/multidevices/tether_utils.py
@@ -46,6 +46,32 @@
   return base64.b64encode(uuid.uuid1().bytes).decode("utf-8").strip("=")
 
 
+def assume_hotspot_test_preconditions(
+    server_device: android_device,
+    client_device: android_device,
+    upstream_type: UpstreamType,
+) -> None:
+  server = server_device.connectivity_multi_devices_snippet
+  client = client_device.connectivity_multi_devices_snippet
+
+  # Assert pre-conditions specific to each upstream type.
+  asserts.skip_if(not client.hasWifiFeature(), "Client requires Wifi feature")
+  asserts.skip_if(
+      not server.hasHotspotFeature(), "Server requires hotspot feature"
+  )
+  if upstream_type == UpstreamType.CELLULAR:
+    asserts.skip_if(
+        not server.hasTelephonyFeature(), "Server requires Telephony feature"
+    )
+  elif upstream_type == UpstreamType.WIFI:
+    asserts.skip_if(
+        not server.isStaApConcurrencySupported(),
+        "Server requires Wifi AP + STA concurrency",
+    )
+  else:
+    raise ValueError(f"Invalid upstream type: {upstream_type}")
+
+
 def setup_hotspot_and_client_for_upstream_type(
     server_device: android_device,
     client_device: android_device,
@@ -60,21 +86,9 @@
   server = server_device.connectivity_multi_devices_snippet
   client = client_device.connectivity_multi_devices_snippet
 
-  # Assert pre-conditions specific to each upstream type.
-  asserts.skip_if(not client.hasWifiFeature(), "Client requires Wifi feature")
-  asserts.skip_if(
-      not server.hasHotspotFeature(), "Server requires hotspot feature"
-  )
   if upstream_type == UpstreamType.CELLULAR:
-    asserts.skip_if(
-        not server.hasTelephonyFeature(), "Server requires Telephony feature"
-    )
     server.requestCellularAndEnsureDefault()
   elif upstream_type == UpstreamType.WIFI:
-    asserts.skip_if(
-        not server.isStaApConcurrencySupported(),
-        "Server requires Wifi AP + STA concurrency",
-    )
     server.ensureWifiIsDefault()
   else:
     raise ValueError(f"Invalid upstream type: {upstream_type}")
@@ -98,6 +112,6 @@
 ) -> None:
   server = server_device.connectivity_multi_devices_snippet
   if upstream_type == UpstreamType.CELLULAR:
-    server.unrequestCellular()
+    server.unregisterAll()
   # Teardown the hotspot.
   server.stopAllTethering()