diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 42bc254..486a690 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -1,6 +1,12 @@
 name: Dart CI
 
-on: push
+on:
+  push:
+    branches:
+    - main
+  pull_request:
+    branches:
+    - main
 
 jobs:
   format:
@@ -57,6 +63,17 @@ jobs:
           flutter test -j 1
         working-directory: packages/isar_test
 
+  test_generator:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: subosito/flutter-action@v2
+      - name: Run Generator Unit tests
+        run: |
+          dart pub get
+          dart test
+        working-directory: packages/isar_generator
+
   drive_ios:
     strategy:
       matrix:
diff --git a/packages/isar_generator/lib/src/isar_analyzer.dart b/packages/isar_generator/lib/src/isar_analyzer.dart
index 6050e44..e75848c 100644
--- a/packages/isar_generator/lib/src/isar_analyzer.dart
+++ b/packages/isar_generator/lib/src/isar_analyzer.dart
@@ -10,7 +10,9 @@ import 'package:isar_generator/src/object_info.dart';
 
 class IsarAnalyzer {
   ObjectInfo analyze(Element modelClass) {
-    if (modelClass is! ClassElement) {
+    if (modelClass is! ClassElement ||
+        modelClass.isEnum ||
+        modelClass.isMixin) {
       err('Only classes may be annotated with @Collection.', modelClass);
     }
 
diff --git a/packages/isar_generator/pubspec.yaml b/packages/isar_generator/pubspec.yaml
index f3e6101..1472e7e 100644
--- a/packages/isar_generator/pubspec.yaml
+++ b/packages/isar_generator/pubspec.yaml
@@ -18,4 +18,7 @@ dependencies:
   source_gen: ^1.2.2
 
 dev_dependencies:
+  build_test: ^2.1.5
+  matcher: ^0.12.12
+  test: ^1.21.0
   very_good_analysis: ^3.0.1
diff --git a/packages/isar_generator/test/error_test.dart b/packages/isar_generator/test/error_test.dart
new file mode 100644
index 0000000..3b90980
--- /dev/null
+++ b/packages/isar_generator/test/error_test.dart
@@ -0,0 +1,33 @@
+import 'dart:io';
+
+import 'package:build/build.dart';
+import 'package:build_test/build_test.dart';
+import 'package:isar_generator/isar_generator.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group('Error case', () {
+    for (final file in Directory('test/errors').listSync(recursive: true)) {
+      if (file is! File || !file.path.endsWith('.dart')) continue;
+
+      test(file.path, () async {
+        final content = await file.readAsLines();
+
+        final errorMessage = content.first.split('//').last.trim();
+
+        var error = '';
+        try {
+          await testBuilder(
+            getIsarGenerator(BuilderOptions.empty),
+            {'a|${file.path}': content.join('\n')},
+            reader: await PackageAssetReader.currentIsolate(),
+          );
+        } catch (e) {
+          error = e.toString();
+        }
+
+        expect(error.toLowerCase(), contains(errorMessage.toLowerCase()));
+      });
+    }
+  });
+}
diff --git a/packages/isar_generator/test/errors/class/abstract.dart b/packages/isar_generator/test/errors/class/abstract.dart
new file mode 100644
index 0000000..670331f
--- /dev/null
+++ b/packages/isar_generator/test/errors/class/abstract.dart
@@ -0,0 +1,8 @@
+// must not be abstract
+
+import 'package:isar/isar.dart';
+
+@Collection()
+abstract class Model {
+  int? id;
+}
diff --git a/packages/isar_generator/test/errors/class/constructor_named.dart b/packages/isar_generator/test/errors/class/constructor_named.dart
new file mode 100644
index 0000000..02a8ecb
--- /dev/null
+++ b/packages/isar_generator/test/errors/class/constructor_named.dart
@@ -0,0 +1,10 @@
+// unnamed constructor
+
+import 'package:isar/isar.dart';
+
+@Collection()
+class Model {
+  Model.create();
+
+  int? id;
+}
diff --git a/packages/isar_generator/test/errors/class/constructor_unknown_parameter.dart b/packages/isar_generator/test/errors/class/constructor_unknown_parameter.dart
new file mode 100644
index 0000000..e41e620
--- /dev/null
+++ b/packages/isar_generator/test/errors/class/constructor_unknown_parameter.dart
@@ -0,0 +1,13 @@
+// constructor parameter does not match a property
+
+import 'package:isar/isar.dart';
+
+@Collection()
+class Model {
+  // ignore: avoid_unused_constructor_parameters
+  Model(this.prop1, String somethingElse);
+
+  int? id;
+
+  final String prop1;
+}
diff --git a/packages/isar_generator/test/errors/class/constructor_wrong_parameter.dart b/packages/isar_generator/test/errors/class/constructor_wrong_parameter.dart
new file mode 100644
index 0000000..a574512
--- /dev/null
+++ b/packages/isar_generator/test/errors/class/constructor_wrong_parameter.dart
@@ -0,0 +1,13 @@
+// constructor parameter type does not match property type
+
+import 'package:isar/isar.dart';
+
+@Collection()
+class Model {
+  // ignore: avoid_unused_constructor_parameters
+  Model(int prop1);
+
+  int? id;
+
+  String prop1 = '5';
+}
diff --git a/packages/isar_generator/test/errors/class/enum.dart b/packages/isar_generator/test/errors/class/enum.dart
new file mode 100644
index 0000000..b563c8b
--- /dev/null
+++ b/packages/isar_generator/test/errors/class/enum.dart
@@ -0,0 +1,7 @@
+// only classes
+
+import 'package:isar/isar.dart';
+
+// ignore: invalid_annotation_target
+@Collection()
+enum Test { a, b, c }
diff --git a/packages/isar_generator/test/errors/class/invalid_name.dart b/packages/isar_generator/test/errors/class/invalid_name.dart
new file mode 100644
index 0000000..670331f
--- /dev/null
+++ b/packages/isar_generator/test/errors/class/invalid_name.dart
@@ -0,0 +1,8 @@
+// must not be abstract
+
+import 'package:isar/isar.dart';
+
+@Collection()
+abstract class Model {
+  int? id;
+}
diff --git a/packages/isar_generator/test/errors/class/mixin.dart b/packages/isar_generator/test/errors/class/mixin.dart
new file mode 100644
index 0000000..fe8debf
--- /dev/null
+++ b/packages/isar_generator/test/errors/class/mixin.dart
@@ -0,0 +1,7 @@
+// only classes
+
+import 'package:isar/isar.dart';
+
+// ignore: invalid_annotation_target
+@Collection()
+mixin Test {}
diff --git a/packages/isar_generator/test/errors/class/private.dart b/packages/isar_generator/test/errors/class/private.dart
new file mode 100644
index 0000000..e042467
--- /dev/null
+++ b/packages/isar_generator/test/errors/class/private.dart
@@ -0,0 +1,9 @@
+// must be public
+
+import 'package:isar/isar.dart';
+
+@Collection()
+// ignore: unused_element
+class _Model {
+  int? id;
+}
diff --git a/packages/isar_generator/test/errors/class/variable.dart b/packages/isar_generator/test/errors/class/variable.dart
new file mode 100644
index 0000000..11270c1
--- /dev/null
+++ b/packages/isar_generator/test/errors/class/variable.dart
@@ -0,0 +1,7 @@
+// only classes
+
+import 'package:isar/isar.dart';
+
+// ignore: invalid_annotation_target
+@Collection()
+const t = 'hello';
diff --git a/packages/isar_generator/test/errors/id/converter.dart b/packages/isar_generator/test/errors/id/converter.dart
new file mode 100644
index 0000000..4e4137c
--- /dev/null
+++ b/packages/isar_generator/test/errors/id/converter.dart
@@ -0,0 +1,24 @@
+// Converters are not allowed for ids
+
+import 'package:isar/isar.dart';
+
+@Collection()
+class Test {
+  @Id()
+  @Converter()
+  late String id;
+}
+
+class Converter extends TypeConverter<String, int> {
+  const Converter();
+
+  @override
+  String fromIsar(int object) {
+    return object.toString();
+  }
+
+  @override
+  int toIsar(String object) {
+    return int.parse(object);
+  }
+}
diff --git a/packages/isar_generator/test/errors/id/duplicate.dart b/packages/isar_generator/test/errors/id/duplicate.dart
new file mode 100644
index 0000000..c2dd52f
--- /dev/null
+++ b/packages/isar_generator/test/errors/id/duplicate.dart
@@ -0,0 +1,12 @@
+// Two or more properties annotated with @Id()
+
+import 'package:isar/isar.dart';
+
+@Collection()
+class Test {
+  @Id()
+  int? id1;
+
+  @Id()
+  int? id2;
+}
diff --git a/packages/isar_generator/test/errors/id/missing.dart b/packages/isar_generator/test/errors/id/missing.dart
new file mode 100644
index 0000000..2164141
--- /dev/null
+++ b/packages/isar_generator/test/errors/id/missing.dart
@@ -0,0 +1,8 @@
+// no int property named "id"
+
+import 'package:isar/isar.dart';
+
+@Collection()
+class Test {
+  late String name;
+}
diff --git a/packages/isar_generator/test/errors/id/not_long.dart b/packages/isar_generator/test/errors/id/not_long.dart
new file mode 100644
index 0000000..567a501
--- /dev/null
+++ b/packages/isar_generator/test/errors/id/not_long.dart
@@ -0,0 +1,9 @@
+// Only int ids are allowed
+
+import 'package:isar/isar.dart';
+
+@Collection()
+class Test {
+  @Id()
+  String? id;
+}
diff --git a/packages/isar_generator/test/errors/id/not_long2.dart b/packages/isar_generator/test/errors/id/not_long2.dart
new file mode 100644
index 0000000..a18612d
--- /dev/null
+++ b/packages/isar_generator/test/errors/id/not_long2.dart
@@ -0,0 +1,10 @@
+// Only int ids are allowed
+
+import 'package:isar/isar.dart';
+
+@Collection()
+class Test {
+  @Id()
+  @Size32()
+  int? id;
+}
diff --git a/packages/isar_generator/test/errors/index/bytes_not_hashed.dart b/packages/isar_generator/test/errors/index/bytes_not_hashed.dart
new file mode 100644
index 0000000..e69de29
diff --git a/packages/isar_generator/test/errors/index/composite_double_not_last.dart b/packages/isar_generator/test/errors/index/composite_double_not_last.dart
new file mode 100644
index 0000000..e69de29
diff --git a/packages/isar_generator/test/errors/index/composite_non_hashed_list.dart b/packages/isar_generator/test/errors/index/composite_non_hashed_list.dart
new file mode 100644
index 0000000..e69de29
diff --git a/packages/isar_generator/test/errors/index/composite_string_value_not_last.dart b/packages/isar_generator/test/errors/index/composite_string_value_not_last.dart
new file mode 100644
index 0000000..e69de29
diff --git a/packages/isar_generator/test/errors/index/contains_id.dart b/packages/isar_generator/test/errors/index/contains_id.dart
new file mode 100644
index 0000000..e69de29
diff --git a/packages/isar_generator/test/errors/index/double_list_hashed.dart b/packages/isar_generator/test/errors/index/double_list_hashed.dart
new file mode 100644
index 0000000..e69de29
diff --git a/packages/isar_generator/test/errors/index/duplicate_name.dart b/packages/isar_generator/test/errors/index/duplicate_name.dart
new file mode 100644
index 0000000..b6ac213
--- /dev/null
+++ b/packages/isar_generator/test/errors/index/duplicate_name.dart
@@ -0,0 +1,14 @@
+// same name
+
+import 'package:isar/isar.dart';
+
+@Collection()
+class Model {
+  int? id;
+
+  @Index(name: 'myindex')
+  String? prop1;
+
+  @Index(name: 'myindex')
+  String? prop2;
+}
diff --git a/packages/isar_generator/test/errors/index/duplicate_property.dart b/packages/isar_generator/test/errors/index/duplicate_property.dart
new file mode 100644
index 0000000..e69de29
diff --git a/packages/isar_generator/test/errors/index/invalid_name.dart b/packages/isar_generator/test/errors/index/invalid_name.dart
new file mode 100644
index 0000000..e69de29
diff --git a/packages/isar_generator/test/errors/index/non_string_hashed.dart b/packages/isar_generator/test/errors/index/non_string_hashed.dart
new file mode 100644
index 0000000..e69de29
diff --git a/packages/isar_generator/test/errors/index/non_string_list_hashed_elements.dart b/packages/isar_generator/test/errors/index/non_string_list_hashed_elements.dart
new file mode 100644
index 0000000..e69de29
diff --git a/packages/isar_generator/test/errors/index/non_unique_replace.dart b/packages/isar_generator/test/errors/index/non_unique_replace.dart
new file mode 100644
index 0000000..e69de29
diff --git a/packages/isar_generator/test/errors/index/property_does_not_exist.dart b/packages/isar_generator/test/errors/index/property_does_not_exist.dart
new file mode 100644
index 0000000..e69de29
diff --git a/packages/isar_generator/test/errors/index/unique_contains_double.dart b/packages/isar_generator/test/errors/index/unique_contains_double.dart
new file mode 100644
index 0000000..e69de29
diff --git a/packages/isar_generator/test/errors/link/backlink_target_does_no_exist.dart b/packages/isar_generator/test/errors/link/backlink_target_does_no_exist.dart
new file mode 100644
index 0000000..e69de29
diff --git a/packages/isar_generator/test/errors/link/backlink_target_is_backlink.dart b/packages/isar_generator/test/errors/link/backlink_target_is_backlink.dart
new file mode 100644
index 0000000..e69de29
diff --git a/packages/isar_generator/test/errors/link/backlink_target_not_a_link.dart b/packages/isar_generator/test/errors/link/backlink_target_not_a_link.dart
new file mode 100644
index 0000000..e69de29
diff --git a/packages/isar_generator/test/errors/link/duplicate_name.dart b/packages/isar_generator/test/errors/link/duplicate_name.dart
new file mode 100644
index 0000000..b958b92
--- /dev/null
+++ b/packages/isar_generator/test/errors/link/duplicate_name.dart
@@ -0,0 +1,18 @@
+// same name
+
+import 'package:isar/isar.dart';
+
+@Collection()
+class Model {
+  int? id;
+
+  final IsarLink<Model2> prop1 = IsarLink();
+
+  @Name('prop1')
+  final IsarLinks<Model2> prop2 = IsarLinks();
+}
+
+@Collection()
+class Model2 {
+  int? id;
+}
diff --git a/packages/isar_generator/test/errors/link/invalid_name.dart b/packages/isar_generator/test/errors/link/invalid_name.dart
new file mode 100644
index 0000000..e69de29
diff --git a/packages/isar_generator/test/errors/link/invalid_type.dart b/packages/isar_generator/test/errors/link/invalid_type.dart
new file mode 100644
index 0000000..e69de29
diff --git a/packages/isar_generator/test/errors/link/late.dart b/packages/isar_generator/test/errors/link/late.dart
new file mode 100644
index 0000000..0a989e0
--- /dev/null
+++ b/packages/isar_generator/test/errors/link/late.dart
@@ -0,0 +1,15 @@
+// must not be late
+
+import 'package:isar/isar.dart';
+
+@Collection()
+class Model {
+  int? id;
+
+  late IsarLink<Model2> link;
+}
+
+@Collection()
+class Model2 {
+  int? id;
+}
diff --git a/packages/isar_generator/test/errors/link/nullable.dart b/packages/isar_generator/test/errors/link/nullable.dart
new file mode 100644
index 0000000..d69d99a
--- /dev/null
+++ b/packages/isar_generator/test/errors/link/nullable.dart
@@ -0,0 +1,15 @@
+// must not be nullable
+
+import 'package:isar/isar.dart';
+
+@Collection()
+class Model {
+  int? id;
+
+  IsarLink<Model2>? link;
+}
+
+@Collection()
+class Model2 {
+  int? id;
+}
diff --git a/packages/isar_generator/test/errors/link/target_not_a_collection.dart b/packages/isar_generator/test/errors/link/target_not_a_collection.dart
new file mode 100644
index 0000000..e69de29
diff --git a/packages/isar_generator/test/errors/link/type_nullable.dart b/packages/isar_generator/test/errors/link/type_nullable.dart
new file mode 100644
index 0000000..e69de29
diff --git a/packages/isar_generator/test/errors/property/converter_constructor_arguments.dart b/packages/isar_generator/test/errors/property/converter_constructor_arguments.dart
new file mode 100644
index 0000000..e69de29
diff --git a/packages/isar_generator/test/errors/property/converter_nullability.dart b/packages/isar_generator/test/errors/property/converter_nullability.dart
new file mode 100644
index 0000000..e69de29
diff --git a/packages/isar_generator/test/errors/property/duplicate_name.dart b/packages/isar_generator/test/errors/property/duplicate_name.dart
new file mode 100644
index 0000000..a7e14ca
--- /dev/null
+++ b/packages/isar_generator/test/errors/property/duplicate_name.dart
@@ -0,0 +1,13 @@
+// same name
+
+import 'package:isar/isar.dart';
+
+@Collection()
+class Model {
+  int? id;
+
+  String? prop1;
+
+  @Name('prop1')
+  String? prop2;
+}
diff --git a/packages/isar_generator/test/errors/property/invalid_name.dart b/packages/isar_generator/test/errors/property/invalid_name.dart
new file mode 100644
index 0000000..e69de29