[tests] Allow include/exclude test categories for .apks (#1024)

In some QA needs to run tests on devices without a network
connection, so an option to disable tests that rely on the network in
`Mono.Android-Tests` is needed.

NUnit has the option to include or exclude tests based on the
`[CategoryAttribute]` custom attribute. Various tests that appear to
use the internet are now decorated with `[Category("InetAccess")]`.
To verify this works, I ran the tests with my internet disabled. The
test run for `Mono.Android-Tests` went down from 106 to 84 tests,
with no failures.

To exclude a category on Windows, specify `$(ExcludeCategories)`

    msbuild Xamarin.Android.sln /t:RunApkTests /p:ExcludeCategories=InetAccess

On MacOS/Linux, set the `EXCLUDECATEGORIES` make variable:

    make run-apk-tests EXCLUDECATEGORIES=InetAccess

If you want to specify multiple categories, use `:` (colon) between
each category. This delimiter is used for various values throughout
Xamarin.Android's build because it works well from the command line
for both MSBuild and make.

Categories can also be explicitly included, by setting the
`$(IncludeCategories)` MSBuild property or the `INCLUDECATEGORIES`
make variable.

Author: jonathanpeppers

Documentation/DevelopmentTips.md

@@ -178,6 +178,20 @@ For example:
 	$ tools/scripts/xabuild /t:DeployTestApks tests/locales/Xamarin.Android.Locale-Tests/Xamarin.Android.Locale-Tests.csproj
 	$ tools/scripts/xabuild /t:RunTestApks    tests/locales/Xamarin.Android.Locale-Tests/Xamarin.Android.Locale-Tests.csproj
 
+## Running `.apk` Projects with Include/Exclude
+
+For example, to exclude tests that use the internet (`InetAccess` category):
+
+	$ make run-apk-tests EXCLUDECATEGORIES=InetAccess
+
+On Windows:
+
+	$ msbuild Xamarin.Android.sln /t:RunApkTests /p:ExcludeCategories=InetAccess
+
+`INCLUDECATEGORIES` and `IncludeCategories` function in the same fashion.
+
+To specify multiple categories, delimit each category with a `:` character. The `:` delimiter works well with both `MSBuild` properties and `make` variables.
+
 ### Running A Single Test Fixture
 
 A single NUnit *Test Fixture* -- a class with the `[TestFixture]`

build-tools/scripts/TestApks.targets

@@ -152,12 +152,17 @@
 
   <Target Name="RunTestApks"
       Condition=" '@(TestApk)' != '' ">
+    <PropertyGroup>
+      <_IncludeCategories Condition=" '$(IncludeCategories)' != '' ">include=$(IncludeCategories)</_IncludeCategories>
+      <_ExcludeCategories Condition=" '$(ExcludeCategories)' != '' ">exclude=$(ExcludeCategories)</_ExcludeCategories>
+    </PropertyGroup>
     <RunInstrumentationTests
         Condition=" '%(TestApk.InstrumentationType)' != ''"
         AdbTarget="$(_AdbTarget)"
         AdbOptions="$(AdbOptions)"
         Component="%(TestApk.Package)/%(TestApk.InstrumentationType)"
         NUnit2TestResultsFile="%(TestApk.ResultsPath)"
+        InstrumentationArguments="$(_IncludeCategories);$(_ExcludeCategories)"
         TestFixture="$(TestFixture)"
         ToolExe="$(AdbToolExe)"
         ToolPath="$(AdbToolPath)">

src/Mono.Android/Test/System.Net/ProxyTest.cs

@@ -6,7 +6,7 @@
 
 namespace System.NetTests {
 
-	[TestFixture]
+	[TestFixture, Category ("InetAccess")]
 	public class ProxyTest {
 
 		// https://bugzilla.xamarin.com/show_bug.cgi?id=14968

src/Mono.Android/Test/System.Net/SslTest.cs

@@ -10,7 +10,7 @@
 
 namespace System.NetTests {
 
-	[TestFixture]
+	[TestFixture, Category ("InetAccess")]
 	public class SslTest {
 
 		// https://xamarin.desk.com/agent/case/35534

src/Mono.Android/Test/Xamarin.Android.Net/AndroidClientHandlerTests.cs

@@ -39,10 +39,10 @@
 using Android.OS;
 
 namespace Xamarin.Android.NetTests {
-
+	[Category("InetAccess")]
 	public abstract class HttpClientHandlerTestBase
 	{
-    protected abstract HttpClientHandler CreateHandler ();
+		protected abstract HttpClientHandler CreateHandler ();
 
 		class Proxy : IWebProxy
 		{

src/Mono.Android/Test/Xamarin.Android.Net/HttpClientIntegrationTests.cs

@@ -38,7 +38,7 @@
 using System.IO;
 
 namespace Xamarin.Android.NetTests {
-
+	[Category ("InetAccess")]
 	public abstract class HttpClientIntegrationTestBase
 	{
     protected abstract HttpClientHandler CreateHandler ();

src/Xamarin.Android.NUnitLite/Gui/Activities/TestSuiteActivity.cs

@@ -103,12 +103,12 @@ protected override void OnResume ()
 
 		protected virtual IEnumerable <string> GetIncludedCategories ()
 		{
-			return null;
+			yield break;
 		}
 
 		protected virtual IEnumerable <string> GetExcludedCategories ()
 		{
-			return null;
+			yield break;
 		}
 
 		// Subclasses can override this method to update the test filtering that the runner will use.

src/Xamarin.Android.NUnitLite/Gui/AndroidRunner.cs

@@ -389,7 +389,8 @@ static void ChainCategoryFilter (IEnumerable <string> categories, bool negate, r
 					gotCategories = true;
 				}
 
-				chain = new AndFilter (chain, negate ? (TestFilter)new NotFilter (filter) : (TestFilter)filter);
+				if (gotCategories)
+					chain = new AndFilter (chain, negate ? (TestFilter)new NotFilter (filter) : (TestFilter)filter);
 			}
 
 			if (!gotCategories)

src/Xamarin.Android.NUnitLite/Gui/Instrumentations/TestSuiteInstrumentation.cs

@@ -146,12 +146,22 @@ protected void AddTest (Assembly assembly)
 
 		protected virtual IEnumerable <string> GetIncludedCategories ()
 		{
-			return null;
+			string include = arguments?.GetString ("include");
+			if (!string.IsNullOrEmpty (include)) {
+				foreach (var category in include.Split (':')) {
+					yield return category;
+				}
+			}
 		}
 
 		protected virtual IEnumerable <string> GetExcludedCategories ()
 		{
-			return null;
+			string exclude = arguments?.GetString ("exclude");
+			if (!string.IsNullOrEmpty (exclude)) {
+				foreach (var category in exclude.Split (':')) {
+					yield return category;
+				}
+			}
 		}
 
 		protected virtual void UpdateFilter ()

tests/Xamarin.Android.Bcl-Tests/TestInstrumentation.cs

@@ -29,7 +29,12 @@ protected override void AddTests ()
 
 		protected override IEnumerable<string> GetExcludedCategories ()
 		{
-			return App.GetExcludedCategories ();
+			foreach (var category in base.GetExcludedCategories ()) {
+				yield return category;
+			}
+			foreach (var category in App.GetExcludedCategories ()) {
+				yield return category;
+			}
 		}
 
 		protected override void UpdateFilter ()