[test] Add test for switch on values with primitive equality

Change-Id: I8de3234f1224e7b0e68b4c1ed190eaa49cbae68f
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/290500
Commit-Queue: Johnni Winther <johnniwinther@google.com>
Reviewed-by: Chloe Stefantsova <cstefantsova@google.com>

tests/language/patterns/primitive_switch_test.dart

@@ -0,0 +1,120 @@
+// Copyright (c) 2023, 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.
+
+// SharedOptions=--enable-experiment=patterns,records
+
+// Verify that switches using only values with primitive equality (excluding
+// the exceptions Symbol and Type) are lowered correctly. These are special
+// cased by the CFE.
+
+import 'package:expect/expect.dart';
+
+abstract class I {}
+
+enum A implements I {
+  a,
+  b,
+  c,
+}
+
+enum B implements I {
+  a,
+  b,
+  c,
+}
+
+int switchExpressionA(A a) => switch (a) {
+      A.a => 0,
+      A.b => 1,
+      A.c => 2,
+    };
+
+int switchStatementA(A a) {
+  switch (a) {
+    case A.a:
+      return 0;
+    case A.b:
+      return 1;
+    case A.c:
+      return 2;
+  }
+}
+
+int switchExpressionB(B b) => switch (b) {
+      B.a => 3,
+      B.b => 4,
+      B.c => 5,
+    };
+
+int switchStatementB(B b) {
+  switch (b) {
+    case B.a:
+      return 3;
+    case B.b:
+      return 4;
+    case B.c:
+      return 5;
+  }
+}
+
+int switchExpressionI(I i) => switch (i) {
+      A.a => 0,
+      A.b => 1,
+      A.c => 2,
+      B.a => 3,
+      B.b => 4,
+      B.c => 5,
+      _ => -1,
+    };
+
+int switchStatementI(I i) {
+  switch (i) {
+    case A.a:
+      return 0;
+    case A.b:
+      return 1;
+    case A.c:
+      return 2;
+    case B.a:
+      return 3;
+    case B.b:
+      return 4;
+    case B.c:
+      return 5;
+    default:
+      return -1;
+  }
+}
+
+main() {
+  Expect.equals(0, switchExpressionA(A.a));
+  Expect.equals(1, switchExpressionA(A.b));
+  Expect.equals(2, switchExpressionA(A.c));
+
+  Expect.equals(0, switchStatementA(A.a));
+  Expect.equals(1, switchStatementA(A.b));
+  Expect.equals(2, switchStatementA(A.c));
+
+  Expect.equals(3, switchExpressionB(B.a));
+  Expect.equals(4, switchExpressionB(B.b));
+  Expect.equals(5, switchExpressionB(B.c));
+
+  Expect.equals(3, switchStatementB(B.a));
+  Expect.equals(4, switchStatementB(B.b));
+  Expect.equals(5, switchStatementB(B.c));
+
+  Expect.equals(0, switchExpressionI(A.a));
+  Expect.equals(1, switchExpressionI(A.b));
+  Expect.equals(2, switchExpressionI(A.c));
+  Expect.equals(3, switchExpressionI(B.a));
+  Expect.equals(4, switchExpressionI(B.b));
+  Expect.equals(5, switchExpressionI(B.c));
+
+  Expect.equals(0, switchStatementI(A.a));
+  Expect.equals(1, switchStatementI(A.b));
+  Expect.equals(2, switchStatementI(A.c));
+  Expect.equals(3, switchStatementI(B.a));
+  Expect.equals(4, switchStatementI(B.b));
+  Expect.equals(5, switchStatementI(B.c));
+}