#1401. [Patterns] cast, null-assert and null-check patterns tests added (#1537)

Cast, null-assert and null-check patterns tests added

Author: sgrekhov

LanguageFeatures/Patterns/cast_A01_t01.dart

@@ -0,0 +1,38 @@
+// Copyright (c) 2022, 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 castPattern ::= primaryPattern 'as' type
+///
+/// A cast pattern is similar to an extractor pattern in that it checks the
+/// matched value against a given type. But where an extractor pattern is
+/// refuted if the value doesn't have that type, a cast pattern throws. Like the
+/// null-assert pattern, this lets you forcibly assert the expected type of some
+/// destructured value.
+///
+/// @description Check some valid cast patterns
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=patterns,records
+
+import "../../Utils/static_type_helper.dart";
+
+main() {
+  (num, Object) r1 = (1, "s");
+  var (i as int, s as String) = r1;
+  i.expectStaticType<Exactly<int>>();
+  s.expectStaticType<Exactly<String>>();
+
+  (Record,) r2 = ((),);
+  var (rec1 as (),) = r2;
+  rec1.expectStaticType<Exactly<()>>();
+
+  ({num n, Object o}) r3 = (n: 1, o: "s");
+  var (n: n as int, o: o as String) = r3;
+  n.expectStaticType<Exactly<int>>();
+  o.expectStaticType<Exactly<String>>();
+
+  ({Record r}) r4 = (r: ());
+  var (r: rec2 as ()) = r4;
+  rec2.expectStaticType<Exactly<()>>();
+}

LanguageFeatures/Patterns/cast_A01_t02.dart

@@ -0,0 +1,61 @@
+// Copyright (c) 2022, 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 castPattern ::= primaryPattern 'as' type
+///
+/// A cast pattern is similar to an extractor pattern in that it checks the
+/// matched value against a given type. But where an extractor pattern is
+/// refuted if the value doesn't have that type, a cast pattern throws. Like the
+/// null-assert pattern, this lets you forcibly assert the expected type of some
+/// destructured value.
+///
+/// @description Check some valid cast patterns in a switch expressions and
+/// statements
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=patterns
+
+import "../../Utils/expect.dart";
+
+const Object zero = 0;
+
+bool isZero(num i) {
+  return switch (i) {
+      zero as int => true,
+      _ => false
+  };
+}
+
+bool isInt(Object o) =>
+  switch (o) {
+    _ as int => true,
+    _ => false
+  };
+
+main() {
+  Expect.isTrue(isZero(0));
+  Expect.isFalse(isZero(1));
+  Expect.isFalse(isZero(-1));
+  Expect.isTrue(isInt(42));
+  Expect.throws(() {
+    isInt("42");
+  });
+
+  int i = 0;
+  switch (i) {
+    case zero as int:
+      Expect.equals(0, i);
+      break;
+    default:
+      Expect.fail("Shouldn't be here");
+  }
+  Object j = 2;
+  switch (j) {
+    case var v as int:
+      Expect.equals(2, v);
+      break;
+    default:
+      Expect.fail("Shouldn't be here");
+  }
+}

LanguageFeatures/Patterns/cast_A01_t03.dart

@@ -0,0 +1,36 @@
+// Copyright (c) 2022, 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 castPattern ::= primaryPattern 'as' type
+///
+/// A cast pattern is similar to an extractor pattern in that it checks the
+/// matched value against a given type. But where an extractor pattern is
+/// refuted if the value doesn't have that type, a cast pattern throws. Like the
+/// null-assert pattern, this lets you forcibly assert the expected type of some
+/// destructured value.
+///
+/// @description Check some valid cast patterns in an if-case statements
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=patterns
+
+import "../../Utils/expect.dart";
+
+const Object zero = 0;
+
+main() {
+  int i = 0;
+  if (i case zero as int) {
+    Expect.equals(0, i);
+  } else {
+    Expect.fail("Shouldn't be here");
+  }
+  bool visited = false;
+  if (i case _ as int) {
+    visited = true;
+  } else {
+    Expect.fail("Shouldn't be here");
+  }
+  Expect.isTrue(visited);
+}

LanguageFeatures/Patterns/cast_A02_t01.dart

@@ -0,0 +1,41 @@
+// Copyright (c) 2022, 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 castPattern ::= primaryPattern 'as' type
+///
+/// A cast pattern is similar to an extractor pattern in that it checks the
+/// matched value against a given type. But where an extractor pattern is
+/// refuted if the value doesn't have that type, a cast pattern throws. Like the
+/// null-assert pattern, this lets you forcibly assert the expected type of some
+/// destructured value.
+///
+/// @description Check that cast pattern throws if the value doesn't have an
+/// expected type
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=patterns,records
+
+import "../../Utils/expect.dart";
+
+main() {
+  (num, Object) r1 = (1, 2);
+  Expect.throws(() {
+    var (i as int, s as String) = r1;
+  });
+
+  (Record,) r2 = ((3.14, name: "pi"),);
+  Expect.throws(() {
+    var (rec1 as (),) = r2;
+  });
+
+  ({num n, Object o}) r3 = (n: 1, o: 2);
+  Expect.throws(() {
+    var (n: n as int, o: o as String) = r3;
+  });
+
+  ({Record r}) r4 = (r: (1, 2));
+  Expect.throws(() {
+    var (r: rec1 as ()) = r4;
+  });
+}

LanguageFeatures/Patterns/cast_A02_t02.dart

@@ -0,0 +1,61 @@
+// Copyright (c) 2022, 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 castPattern ::= primaryPattern 'as' type
+///
+/// A cast pattern is similar to an extractor pattern in that it checks the
+/// matched value against a given type. But where an extractor pattern is
+/// refuted if the value doesn't have that type, a cast pattern throws. Like the
+/// null-assert pattern, this lets you forcibly assert the expected type of some
+/// destructured value.
+///
+/// @description Check that cast pattern throws if the value doesn't have an
+/// expected type
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=patterns
+
+import "../../Utils/expect.dart";
+
+bool isOdd1(Object o) =>
+  switch (o) {
+    var v as int => v.isOdd,
+    _ => false
+  };
+
+bool isOdd2(Object o) {
+  switch (o) {
+    case var v as int:
+      return v.isOdd;
+    default:
+      return false;
+  }
+}
+
+bool isOdd3(Object o) {
+  if (o case var v as int) {
+    return v.isOdd;
+  }
+  return false;
+}
+
+main() {
+  Expect.isTrue(isOdd1(1));
+  Expect.isFalse(isOdd1(2));
+  Expect.throws(() {
+    isOdd1("1");
+  });
+
+  Expect.isTrue(isOdd2(1));
+  Expect.isFalse(isOdd2(2));
+  Expect.throws(() {
+    isOdd2("1");
+  });
+
+  Expect.isTrue(isOdd3(1));
+  Expect.isFalse(isOdd3(2));
+  Expect.throws(() {
+    isOdd3("1");
+  });
+}

LanguageFeatures/Patterns/null_assert_A01_t01.dart

@@ -0,0 +1,37 @@
+// Copyright (c) 2022, 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 nullAssertPattern ::= primaryPattern '!'
+///
+/// A null-assert pattern is similar to a null-check pattern in that it permits
+/// non-null values to flow through. But a null-assert throws if the matched
+/// value is null. It lets you forcibly assert that you know a value shouldn't
+/// be null, much like the corresponding ! null-assert expression.
+///
+/// @description Check null-assert in a variable pattern
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=patterns,records
+
+import "../../Utils/static_type_helper.dart";
+import "../../Utils/expect.dart";
+
+test1((int?, int?) position) {
+  var (x!, _!) = position;
+  x.expectStaticType<Exactly<int>>();
+  x.isOdd;
+  Expect.equals(1, x);
+}
+
+test2(({int? x, int? y}) position) {
+  var (x: x!, y: _!) = position;
+  x.expectStaticType<Exactly<int>>();
+  x.isOdd;
+  Expect.equals(1, x);
+}
+
+main() {
+  test1((1, 1));
+  test2((x: 1, y: 1));
+}

LanguageFeatures/Patterns/null_assert_A01_t02.dart

@@ -0,0 +1,41 @@
+// Copyright (c) 2022, 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 nullAssertPattern ::= primaryPattern '!'
+///
+/// A null-assert pattern is similar to a null-check pattern in that it permits
+/// non-null values to flow through. But a null-assert throws if the matched
+/// value is null. It lets you forcibly assert that you know a value shouldn't
+/// be null, much like the corresponding ! null-assert expression.
+///
+/// @description Check null-assert pattern in a switch statement
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=patterns
+
+import "../../Utils/static_type_helper.dart";
+import "../../Utils/expect.dart";
+
+test(List<String?> list, [bool testVisited = false]) {
+  bool visited = false;
+  switch (list) {
+    case ['name', var name!]:
+      name.expectStaticType<Exactly<String>>();
+      name.substring(0);
+      break;
+    case ['answer', _!]:
+      visited = true;
+      break;
+    default:
+      Expect.fail("Wrong branch of code");
+  }
+  if (testVisited) {
+    Expect.isTrue(visited);
+  }
+}
+
+main() {
+  test(['name', 'Lily']);
+  test(['answer', '42'], true);
+}

LanguageFeatures/Patterns/null_assert_A01_t03.dart

@@ -0,0 +1,39 @@
+// Copyright (c) 2022, 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 nullAssertPattern ::= primaryPattern '!'
+///
+/// A null-assert pattern is similar to a null-check pattern in that it permits
+/// non-null values to flow through. But a null-assert throws if the matched
+/// value is null. It lets you forcibly assert that you know a value shouldn't
+/// be null, much like the corresponding ! null-assert expression.
+///
+/// @description Check null-assert pattern in an if-case statement
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=patterns
+
+import "../../Utils/static_type_helper.dart";
+import "../../Utils/expect.dart";
+
+test(List<String?> list, [bool testVisited = false]) {
+  bool visited = false;
+  if (list case ['name', var name!]) {
+    name.expectStaticType<Exactly<String>>();
+    name.substring(0);
+    visited = true;
+  } else if (list case ['answer', _!]) {
+    visited = true;
+  } else {
+    Expect.fail("Wrong branch of code");
+  }
+  if (testVisited) {
+    Expect.isTrue(visited);
+  }
+}
+
+main() {
+  test(['name', 'Lily']);
+  test(['answer', '42'], true);
+}

LanguageFeatures/Patterns/null_assert_A01_t04.dart

@@ -0,0 +1,30 @@
+// Copyright (c) 2022, 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 nullAssertPattern ::= primaryPattern '!'
+///
+/// A null-assert pattern is similar to a null-check pattern in that it permits
+/// non-null values to flow through. But a null-assert throws if the matched
+/// value is null. It lets you forcibly assert that you know a value shouldn't
+/// be null, much like the corresponding ! null-assert expression.
+///
+/// @description Check null-assert pattern in a switch expression
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=patterns
+
+import "../../Utils/expect.dart";
+
+String test(List<String?> list) {
+  return switch (list) {
+    ['name', var name!] => name.substring(0),
+    ['answer', _!] => "answer",
+    _ => "default"
+  };
+}
+
+main() {
+  Expect.equals("Lily", test(['name', 'Lily']));
+  Expect.equals("answer", test(['answer', '42']));
+}