Disallow uninitialized non-nullable variables

pkg/analyzer/test/src/task/strong/non_null_checker_test.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // These tests are for an experimental feature that treats Dart primitive types
 // (int, bool, double, etc.) as non-nullable. This file is not evidence for an
 // intention to officially support non-nullable primitives in Dart (or general
 // NNBD, for that matter) so don't get too crazy about it.
 
 library analyzer.test.src.task.non_null_primitives.checker_test;
@@ skipping 30 matching lines @@
   }
 }
 ''');
   }
 
   void test_nullableTypes() {
     // By default x can be set to null.
     checkFile('int x = null;');
   }
 
-  void test_uninitialized_nonnullable() {
-    // If `int`s are non-nullable, then this code should throw an error.
-    addFile('int x;');
-    check(nonnullableTypes: <String>['dart:core,int']);
-  }
-
   void test_initialize_nonnullable_with_null() {
     addFile('int x = /*error:INVALID_ASSIGNMENT*/null;');
     check(nonnullableTypes: <String>['dart:core,int']);
   }
 
   void test_initialize_nonnullable_with_valid_value() {
     addFile('int x = 0;');
     check(nonnullableTypes: <String>['dart:core,int']);
   }
 
   void test_assign_null_to_nonnullable() {
     addFile('''
 int x = 0;
 
 main() {
   x = 1;
   x = /*error:INVALID_ASSIGNMENT*/null;
 }
 ''');
     check(nonnullableTypes: <String>['dart:core,int']);
   }
 
+  void test_uninitialized_nonnullable_local_variable() {
+    // Ideally, we will do flow analysis and throw an error only if a variable
+    // is used before it has been initialized.
+    addFile('main() { int /*error:NON_NULLABLE_FIELD_NOT_INITIALIZED*/x; }');
+    check(nonnullableTypes: <String>['dart:core,int']);
+  }
+
+  void test_uninitialized_nonnullable_top_level_variable_declaration() {
+    // If `int`s are non-nullable, then this code should throw an error.
+    addFile('int /*error:NON_NULLABLE_FIELD_NOT_INITIALIZED*/x;');
+    check(nonnullableTypes: <String>['dart:core,int']);
+  }
+
+  void test_uninitialized_nonnullable_field_declaration() {
+    addFile('''
+void foo() {}
+
+class A {
+  // Ideally, we should allow x to be init in the constructor, but that requires
+  // too much complication in the checker, so for now we throw a static error at
+  // the declaration site.
+  int /*error:NON_NULLABLE_FIELD_NOT_INITIALIZED*/x;
+
+  A();
+}
+''');
+    check(nonnullableTypes: <String>['dart:core,int']);
+  }
+
+  void test_prefer_final_to_non_nullable_error() {
+    addFile('main() { final int /*error:FINAL_NOT_INITIALIZED*/x; }');
+    addFile('final int /*error:FINAL_NOT_INITIALIZED*/x;');
+    addFile('''
+void foo() {}
+
+class A {
+  final int x;
+
+  /*warning:FINAL_NOT_INITIALIZED_CONSTRUCTOR_1*/A();
+}
+''');
+    check(nonnullableTypes: <String>['dart:core,int']);
+  }
+
   // Default example from NNBD document.
   final String defaultNnbdExample = '''
 class Point {
   final int x, y;
   Point(this.x, this.y);
   Point operator +(Point other) => new Point(x + other.x, y + other.y);
   String toString() => "x: \$x, y: \$y";
 }
 
 void main() {
@@ skipping 51 matching lines @@
     // A nullable expression can be passed as an argument to `Point` in default
     // mode.
     addFile(_withError(defaultNnbdExampleMod2, "error:INVALID_ASSIGNMENT"));
     check(nonnullableTypes: <String>['dart:core,int']);
   }
 }
 
 String _withError(String file, String error) {
   return ("" + file).replaceFirst("boom", error);
 }