[xaprepare] Allow desired Android SDK platform levels to be selected.

build-tools/automation/yaml-templates/setup-test-environment.yaml

@@ -53,7 +53,7 @@ steps:
 
 - template: run-xaprepare.yaml
   parameters:
-    arguments: --s=AndroidTestDependencies
+    arguments: --s=AndroidTestDependencies  --android-sdk-platforms="19,21,26,32"
     xaSourcePath: ${{ parameters.xaSourcePath }}
 
 - task: DotNetCoreCLI@2

build-tools/xaprepare/xaprepare/Application/AndroidToolchainComponent.cs

@@ -44,9 +44,13 @@ public void AddToInventory ()
 
 	class AndroidPlatformComponent : AndroidToolchainComponent
 	{
+		public string ApiLevel { get; }
+
 		public AndroidPlatformComponent (string name, string apiLevel, string pkgRevision)
 			: base (name, Path.Combine ("platforms", $"android-{apiLevel}"), pkgRevision: pkgRevision, buildToolName: $"android-sdk-{name}", buildToolVersion:$"{apiLevel}.{pkgRevision}")
-		{}
+		{
+			ApiLevel = apiLevel;
+		}
 	}
 
 	[Flags]

build-tools/xaprepare/xaprepare/Application/Context.cs

@@ -333,6 +333,11 @@ public string DebugFileExtension {
 		/// </summary>
 		public RefreshableComponent ComponentsToRefresh { get; set; }
 
+		/// <summary>
+		///   Collection of Android SDK platform levels to be installed.
+		/// </summary>
+		public IEnumerable<string> AndroidSdkPlatforms { get; set; } = Enumerable.Empty<string> ();
+
 		/// <summary>
 		/// Set by the --mono-archive-url flag
 		/// </summary>

build-tools/xaprepare/xaprepare/Main.cs

@@ -34,6 +34,7 @@ sealed class ParsedOptions
 			public string? MonoArchiveCustomUrl { get; set; }
 			public bool EnableAll              { get; set; }
 			public RefreshableComponent RefreshList { get; set; }
+			public IEnumerable<string> AndroidSdkPlatforms { get; set; } = Enumerable.Empty<string> ();
 		}
 
 		public static int Main (string[] args)
@@ -112,6 +113,7 @@ static async Task<int> Run (string[] args)
 				{"ignore-max-mono-version=", $"Ignore the maximum supported Mono version restriction", v => parsedOptions.IgnoreMaxMonoVersion = ParseBoolean (v)},
 				{"ignore-min-mono-version=", $"Ignore the minimum supported Mono version restriction", v => parsedOptions.IgnoreMinMonoVersion = ParseBoolean (v)},
 				{"mono-archive-url=", "Use a specific URL for the mono archive.", v => parsedOptions.MonoArchiveCustomUrl = v?.Trim () },
+				{"android-sdk-platforms=", "Comma separated list of Android SDK platform levels to be installed. Defaults to all if no value is provided.", v => parsedOptions.AndroidSdkPlatforms = ParseAndroidSdkPlatformLevels (v?.Trim () ?? String.Empty) },
 				"",
 				{"h|help", "Show this help message", v => parsedOptions.ShowHelp = true },
 			};
@@ -148,6 +150,7 @@ static async Task<int> Run (string[] args)
 			Context.Instance.MonoArchiveCustomUrl  = parsedOptions.MonoArchiveCustomUrl ?? String.Empty;
 			Context.Instance.EnableAllTargets      = parsedOptions.EnableAll;
 			Context.Instance.ComponentsToRefresh   = parsedOptions.RefreshList;
+			Context.Instance.AndroidSdkPlatforms   = parsedOptions.AndroidSdkPlatforms;
 
 			if (!String.IsNullOrEmpty (parsedOptions.Configuration))
 				Context.Instance.Configuration = parsedOptions.Configuration!;
@@ -340,5 +343,9 @@ RefreshableComponent ParseSingleComponent (string component) {
 			}
 		}
 
+		static IEnumerable<string> ParseAndroidSdkPlatformLevels (string list)
+		{
+			return list.Split (',').Select (item => item.Trim ());
+		}
 	}
 }

build-tools/xaprepare/xaprepare/Steps/Step_Android_SDK_NDK.cs

@@ -253,6 +253,14 @@ void Check (Context context, string packageCacheDir, string sdkRoot, AndroidTool
 				return;
 			}
 
+			// If only specific Android SDK platforms were requested, ignore ones that were not requested
+			if (component is AndroidPlatformComponent apc && context.AndroidSdkPlatforms.Any ()) {
+				if (!context.AndroidSdkPlatforms.Contains (apc.ApiLevel)) {
+					LogStatus ($"skipping, not requested", padLeft, Log.InfoColor);
+					return;
+				}
+			}
+
 			if (missing)
 				LogStatus (statusMissing, padLeft, ConsoleColor.Magenta);
 			else