#3057. Add conditional statements tests (#3106)

Add conditional statements tests

Author: sgrekhov

TypeSystem/flow-analysis/definite_assignment_A02_t01.dart

@@ -2,16 +2,18 @@
 // 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 and if statement
+/// @description Checks that if variable assigned in both branches of `if`
+/// statement then it is definitely assigned.
 /// @author [email protected]
 
 main() {
   int n;
-  bool b = true;
+  bool b = 2 > 1;
   if (b) {
     n = 42;
   } else {

TypeSystem/flow-analysis/definite_assignment_A02_t02.dart

@@ -2,11 +2,14 @@
 // 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 and if statement
+/// @description Checks that if a variable is assigned only in one branch of an
+/// `if` statement and the condition is not `true` or `false` literal then it is
+/// not definitely assigned.
 /// @author [email protected]
 
 main() {

TypeSystem/flow-analysis/definite_assignment_A02_t03.dart

@@ -2,11 +2,14 @@
 // 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 and if statement
+/// @description Checks that if a variable is assigned only in one branch of an
+/// `if` statement and the condition is not `true` or `false` literal then it is
+/// not definitely assigned.
 /// @author [email protected]
 
 main() {

TypeSystem/flow-analysis/definite_assignment_A02_t04.dart

@@ -2,11 +2,14 @@
 // 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 and if statement
+/// @description Checks that if variable assigned in the `then` branch of `if`
+/// statement and the condition is the `true` literal then it is definitely
+/// assigned.
 /// @author [email protected]
 
 main() {

TypeSystem/flow-analysis/definite_assignment_A02_t05.dart

@@ -2,11 +2,14 @@
 // 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 and if statement
+/// @description Checks that if variable assigned in the `else` branch of `if`
+/// statement and the condition is the `false` literal then it is definitely
+/// assigned.
 /// @author [email protected]
 
 main() {

TypeSystem/flow-analysis/reachability_A01_t01.dart

@@ -19,7 +19,7 @@ void test(Never n) {
   bool b = (() => true)();
   if (b) {
     n;        // The code after this point is unreachable
-    i = 42;   // Variable is initialized in a dead code. This leaves it definitely unassigned
+    i = 42;   // This is dead code, which leaves `i` definitely unassigned.
   }
   i; // It is an error to read a local late variable when it is definitely unassigned.
 //^

TypeSystem/flow-analysis/reachability_A01_t02.dart

@@ -22,7 +22,7 @@ main() {
     bool b = (() => true)();
     if (b) {
       n;        // The code after this point is unreachable
-      i = 42;   // Variable is initialized in a dead code. This leaves it definitely unassigned
+      i = 42;   // This is dead code, which leaves `i` definitely unassigned.
     }
     i; // It is an error to read a local late variable when it is definitely unassigned.
 //  ^

TypeSystem/flow-analysis/reachability_A01_t11.dart

@@ -19,7 +19,7 @@ void test<T extends Never>(T n) {
   bool b = (() => true)();
   if (b) {
     n;        // The code after this point is unreachable
-    i = 42;   // Variable is initialized in a dead code. This leaves it definitely unassigned
+    i = 42;   // This is dead code, which leaves `i` definitely unassigned.
   }
   i; // It is an error to read a local late variable when it is definitely unassigned.
 //^

TypeSystem/flow-analysis/reachability_A01_t12.dart

@@ -23,7 +23,7 @@ class C<T extends Never> {
       bool b = (() => true)();
       if (b) {
         n; // The code after this point is unreachable
-        i = 42; // Variable is initialized in a dead code. This leaves it definitely unassigned
+        i = 42; // This is dead code, which leaves `i` definitely unassigned.
       }
       i; // It is an error to read a local late variable when it is definitely unassigned.
 //    ^

TypeSystem/flow-analysis/reachability_A01_t17.dart

@@ -20,7 +20,7 @@ void test(Never n) {
   if (b) {
     [
       n,        // The code after this point is unreachable
-      i = 42    // Variable is initialized in a dead code. This leaves it definitely unassigned
+      i = 42    // This is dead code, which leaves `i` definitely unassigned.
     ];
   }
   i; // It is an error to read a local late variable when it is definitely unassigned.