Bug 1582150 - Don't rely on page stop in aboutConfig test. r=snorp

Trying to access `about:config` will fail even before the page has started loading so we don't get the usual flow.

For a normal page (that fails to load) it is:

- OnLoadRequest
- OnPageStart
- OnLoadError
- OnPageStop

but for about:config it's just

- OnLoadRequest
- OnLoadError

So we just wait for the OnLoadError message instead.

Differential Revision: https://phabricator.services.mozilla.com/D46369

--HG--
extra : moz-landing-system : lando

mobile/android/geckoview/src/androidTest/java/org/mozilla/geckoview/test/RuntimeSettingsTest.kt

@@ -8,14 +8,18 @@ import android.provider.Settings
 import android.support.test.InstrumentationRegistry
 import android.support.test.filters.MediumTest
 import android.support.test.runner.AndroidJUnit4
+import android.util.Log
 import org.hamcrest.Matchers.*
 import org.junit.Ignore
 import org.junit.Test
 import org.junit.runner.RunWith
+import org.mozilla.geckoview.GeckoResult
 import kotlin.math.roundToInt
 import org.mozilla.geckoview.GeckoSession
+import org.mozilla.geckoview.WebRequestError
 import org.mozilla.geckoview.test.rule.GeckoSessionTestRule.AssertCalled
 import org.mozilla.geckoview.test.util.Callbacks
+import java.util.concurrent.atomic.AtomicBoolean
 
 @RunWith(AndroidJUnit4::class)
 @MediumTest
@@ -144,21 +148,21 @@ class RuntimeSettingsTest : BaseSessionTest() {
     }
 
     @Test
-    @Ignore // Bug 1582150
     fun aboutConfig() {
-        val settings = sessionRule.runtime.settings;
+        val settings = sessionRule.runtime.settings
 
         assertThat("about:config should be disabled by default",
                 settings.aboutConfigEnabled, equalTo(false))
-        mainSession.delegateDuringNextWait(object : Callbacks.ProgressDelegate {
-            @AssertCalled
-            override fun onPageStop(session: GeckoSession, success: Boolean) {
-                assertThat("about:config load should fail", success, equalTo(false))
-            }
-        })
 
         mainSession.loadUri("about:config")
-        mainSession.waitForPageStop()
+        mainSession.waitUntilCalled(object : Callbacks.NavigationDelegate {
+            @AssertCalled
+            override fun onLoadError(session: GeckoSession, uri: String?, error: WebRequestError):
+                    GeckoResult<String>? {
+                assertThat("about:config should not load.", uri, equalTo("about:config"))
+                return null
+            }
+        })
 
         settings.aboutConfigEnabled = true