ethernet: add test for enable/disable interface

More tests to come, specifically around toggling carrier up / down, once
that behavior has been fixed.

Test: atest EthernetManagerTest
Change-Id: I2424bd4f39013302d416e8e1ae5c8a7dd357c250
diff --git a/tests/cts/net/src/android/net/cts/EthernetManagerTest.kt b/tests/cts/net/src/android/net/cts/EthernetManagerTest.kt
index 1a3b01e..d72cf1f 100644
--- a/tests/cts/net/src/android/net/cts/EthernetManagerTest.kt
+++ b/tests/cts/net/src/android/net/cts/EthernetManagerTest.kt
@@ -718,4 +718,18 @@
         releaseTetheredInterface()
         listener.assertNoCallback()
     }
+
+    @Test
+    fun testEnableDisableInterface_withActiveRequest() {
+        val iface = createInterface()
+        val cb = requestNetwork(ETH_REQUEST)
+        cb.expectAvailable()
+        cb.assertNeverLost()
+
+        disableInterface(iface).expectResult(iface.name)
+        cb.eventuallyExpectLost()
+
+        enableInterface(iface).expectResult(iface.name)
+        cb.expectAvailable()
+    }
 }