[native_assets_cli] Replace TypeErrors with FormatExceptions

pkgs/native_assets_cli/CHANGELOG.md

@@ -2,6 +2,8 @@
 
 - Added topics.
 - Fixed metadata example.
+- Throws `FormatException`s instead of `TypeError`s when failing to parse Yaml
+  ([#109](https://github.com/dart-lang/native/issues/109)).
 
 ## 0.1.0
 

pkgs/native_assets_cli/lib/src/model/asset.dart

@@ -27,8 +27,8 @@ abstract class AssetPath {
   }
 
   factory AssetPath.fromYaml(YamlMap yamlMap) {
-    final pathType = yamlMap[_pathTypeKey] as String;
-    final uriString = yamlMap[_uriKey] as String?;
+    final pathType = as<String>(yamlMap[_pathTypeKey]);
+    final uriString = as<String?>(yamlMap[_uriKey]);
     final uri = uriString != null ? Uri(path: uriString) : null;
     return AssetPath(pathType, uri);
   }
@@ -203,10 +203,10 @@ class Asset {
   });
 
   factory Asset.fromYaml(YamlMap yamlMap) => Asset(
-        name: yamlMap[_nameKey] as String,
-        path: AssetPath.fromYaml(yamlMap[_pathKey] as YamlMap),
-        target: Target.fromString(yamlMap[_targetKey] as String),
-        linkMode: LinkMode.fromName(yamlMap[_linkModeKey] as String),
+        name: as<String>(yamlMap[_nameKey]),
+        path: AssetPath.fromYaml(as<YamlMap>(yamlMap[_pathKey])),
+        target: Target.fromString(as<String>(yamlMap[_targetKey])),
+        linkMode: LinkMode.fromName(as<String>(yamlMap[_linkModeKey])),
       );
 
   static List<Asset> listFromYamlString(String yaml) {
@@ -215,14 +215,14 @@ class Asset {
       return [];
     }
     return [
-      for (final yamlElement in yamlObject as YamlList)
-        Asset.fromYaml(yamlElement as YamlMap),
+      for (final yamlElement in as<YamlList>(yamlObject))
+        Asset.fromYaml(as<YamlMap>(yamlElement)),
     ];
   }
 
   static List<Asset> listFromYamlList(YamlList yamlList) => [
         for (final yamlElement in yamlList)
-          Asset.fromYaml(yamlElement as YamlMap),
+          Asset.fromYaml(as<YamlMap>(yamlElement)),
       ];
 
   Asset copyWith({

pkgs/native_assets_cli/lib/src/model/build_config.dart

@@ -443,7 +443,7 @@ class BuildConfig {
     }
     final result = <String, Metadata>{};
     for (final entry in fileValue.entries) {
-      final packageName = entry.key;
+      final packageName = as<String>(entry.key);
       final defines = entry.value;
       if (defines is! Map) {
         throw FormatException("Unexpected value '$defines' for key "
@@ -452,13 +452,11 @@ class BuildConfig {
       }
       final packageResult = <String, Object>{};
       for (final entry2 in defines.entries) {
-        final key = entry2.key;
-        assert(key is String);
-        final value = entry2.value;
-        assert(value != null);
-        packageResult[key as String] = value as Object;
+        final key = as<String>(entry2.key);
+        final value = as<Object>(entry2.value);
+        packageResult[key] = value;
       }
-      result[packageName as String] = Metadata(packageResult.sortOnKey());
+      result[packageName] = Metadata(packageResult.sortOnKey());
     }
     return result.sortOnKey();
   }

pkgs/native_assets_cli/lib/src/model/build_output.dart

@@ -43,12 +43,12 @@ class BuildOutput {
   static const _versionKey = 'version';
 
   factory BuildOutput.fromYamlString(String yaml) {
-    final yamlObject = loadYaml(yaml) as YamlMap;
-    return BuildOutput.fromYaml(yamlObject);
+    final yamlObject = loadYaml(yaml);
+    return BuildOutput.fromYaml(as<YamlMap>(yamlObject));
   }
 
   factory BuildOutput.fromYaml(YamlMap yamlMap) {
-    final outputVersion = Version.parse(yamlMap['version'] as String);
+    final outputVersion = Version.parse(as<String>(yamlMap['version']));
     if (outputVersion.major > version.major) {
       throw FormatException(
         'The output version $outputVersion is newer than the '
@@ -65,11 +65,11 @@ class BuildOutput {
     }
 
     return BuildOutput(
-      timestamp: DateTime.parse(yamlMap[_timestampKey] as String),
-      assets: Asset.listFromYamlList(yamlMap[_assetsKey] as YamlList),
+      timestamp: DateTime.parse(as<String>(yamlMap[_timestampKey])),
+      assets: Asset.listFromYamlList(as<YamlList>(yamlMap[_assetsKey])),
       dependencies:
-          Dependencies.fromYaml(yamlMap[_dependenciesKey] as YamlList?),
-      metadata: Metadata.fromYaml(yamlMap[_metadataKey] as YamlMap?),
+          Dependencies.fromYaml(as<YamlList?>(yamlMap[_dependenciesKey])),
+      metadata: Metadata.fromYaml(as<YamlMap?>(yamlMap[_metadataKey])),
     );
   }
 

pkgs/native_assets_cli/lib/src/model/dependencies.dart

@@ -25,7 +25,7 @@ class Dependencies {
   factory Dependencies.fromYaml(YamlList? yamlList) => Dependencies([
         if (yamlList != null)
           for (final dependency in yamlList)
-            fileSystemPathToUri(dependency as String),
+            fileSystemPathToUri(as<String>(dependency)),
       ]);
 
   List<String> toYaml() => [

pkgs/native_assets_cli/lib/src/model/metadata.dart

@@ -14,10 +14,10 @@ class Metadata {
   const Metadata(this.metadata);
 
   factory Metadata.fromYaml(YamlMap? yamlMap) =>
-      Metadata(yamlMap?.cast<String, Object>() ?? {});
+      Metadata(yamlMap?.formatCast<String, Object>() ?? {});
 
   factory Metadata.fromYamlString(String yaml) {
-    final yamlObject = loadYaml(yaml) as YamlMap;
+    final yamlObject = as<YamlMap>(loadYaml(yaml));
     return Metadata.fromYaml(yamlObject);
   }
 

pkgs/native_assets_cli/lib/src/utils/yaml.dart

@@ -16,3 +16,18 @@ String yamlEncode(Object yamlEncoding) {
   );
   return editor.toString();
 }
+
+T as<T>(Object? object) {
+  if (object is T) {
+    return object;
+  }
+  throw FormatException(
+    "Unexpected value '$object' in YAML. Expected a $T.",
+  );
+}
+
+extension YamlMapCast on YamlMap {
+  Map<K, V> formatCast<K, V>() => <K, V>{
+        for (final e in entries) as<K>(e.key): as<V>(e.value),
+      };
+}

pkgs/native_assets_cli/test/model/build_output_test.dart

@@ -109,4 +109,54 @@ version: ${BuildOutput.version}''';
       );
     });
   }
+
+  test('format exception', () {
+    expect(
+      () => BuildOutput.fromYamlString('''timestamp: 2022-11-10 13:25:01.000
+assets:
+  - name: foo
+    link_mode: dynamic
+    path:
+      path_type:
+        some: map
+      uri: path/to/libfoo.so
+    target: android_x64
+dependencies: []
+metadata:
+  key: value
+version: ${BuildOutput.version}'''),
+      throwsFormatException,
+    );
+    expect(
+      () => BuildOutput.fromYamlString('''timestamp: 2022-11-10 13:25:01.000
+assets:
+  - name: foo
+    link_mode: dynamic
+    path:
+      path_type: absolute
+      uri: path/to/libfoo.so
+    target: android_x64
+dependencies:
+  1: foo
+metadata:
+  key: value
+version: ${BuildOutput.version}'''),
+      throwsFormatException,
+    );
+    expect(
+      () => BuildOutput.fromYamlString('''timestamp: 2022-11-10 13:25:01.000
+assets:
+  - name: foo
+    link_mode: dynamic
+    path:
+      path_type: absolute
+      uri: path/to/libfoo.so
+    target: android_x64
+dependencies: []
+metadata:
+  123: value
+version: ${BuildOutput.version}'''),
+      throwsFormatException,
+    );
+  });
 }