#3057. Add pattern-based definite assignment tests (#3102)

Author: sgrekhov

TypeSystem/flow-analysis/definite_assignment_A01_t01.dart

@@ -2,9 +2,10 @@
 // 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.
 
-/// @assertion assigned is a boolean value indicating whether the variable has
-/// definitely been assigned at the given point in the source code. When assigned
-/// is true, we say that the variable is definitely assigned at that point.
+/// @assertion `assigned` is a boolean value indicating whether the variable has
+/// definitely been assigned at the given point in the source code. When
+/// `assigned` is true, we say that the variable is definitely assigned at that
+/// point.
 ///
 /// @description Checks definite assignment via assignment
 /// @author [email protected]

TypeSystem/flow-analysis/definite_assignment_A01_t02.dart

@@ -0,0 +1,20 @@
+// Copyright (c) 2025, 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.
+
+/// @assertion `assigned` is a boolean value indicating whether the variable has
+/// definitely been assigned at the given point in the source code. When
+/// `assigned` is true, we say that the variable is definitely assigned at that
+/// point.
+///
+/// @description Checks definite assignment via record pattern assignment.
+/// @author [email protected]
+
+main() {
+  int i, j;
+
+  (i,) = (42,);
+  i;  // Definitely assigned
+  (x: j) = (x: 42);
+  j;
+}

TypeSystem/flow-analysis/definite_assignment_A01_t03.dart

@@ -0,0 +1,18 @@
+// Copyright (c) 2025, 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.
+
+/// @assertion `assigned` is a boolean value indicating whether the variable has
+/// definitely been assigned at the given point in the source code. When
+/// `assigned` is true, we say that the variable is definitely assigned at that
+/// point.
+///
+/// @description Checks definite assignment via list pattern assignment.
+/// @author [email protected]
+
+main() {
+  int n;
+
+  [n] = [42];
+  n;  // Definitely assigned
+}

TypeSystem/flow-analysis/definite_assignment_A01_t04.dart

@@ -0,0 +1,18 @@
+// Copyright (c) 2025, 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.
+
+/// @assertion `assigned` is a boolean value indicating whether the variable has
+/// definitely been assigned at the given point in the source code. When
+/// `assigned` is true, we say that the variable is definitely assigned at that
+/// point.
+///
+/// @description Checks definite assignment via map pattern assignment.
+/// @author [email protected]
+
+main() {
+  int n;
+
+  {"key": n} = {"key": 42};
+  n;  // Definitely assigned
+}

TypeSystem/flow-analysis/definite_assignment_A01_t05.dart

@@ -0,0 +1,22 @@
+// Copyright (c) 2025, 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.
+
+/// @assertion `assigned` is a boolean value indicating whether the variable has
+/// definitely been assigned at the given point in the source code. When
+/// `assigned` is true, we say that the variable is definitely assigned at that
+/// point.
+///
+/// @description Checks definite assignment via object pattern assignment.
+/// @author [email protected]
+
+class C {
+  int x;
+  C(this.x);
+}
+
+main() {
+  int n;
+  C(x: n) = C(42);
+  n;  // Definitely assigned
+}