C#: Add tests for null-coalescing assignment

Author: hvitved

csharp/ql/test/query-tests/Nullness/E.cs

@@ -385,6 +385,18 @@ static bool Ex37(E e1, E e2)
             return true;
         return e1.Long == e2.Long; // GOOD (false positive)
     }
+
+    int Ex38(int? i)
+    {
+        i ??= 0;
+        return i.Value; // GOOD (false positive)
+    }
+
+    System.Drawing.Color Ex39(System.Drawing.Color? color)
+    {
+        color ??= System.Drawing.Color.White;
+        return color.Value; // GOOD (false positive)
+    }
 }
 
 public static class Extensions
@@ -393,4 +405,4 @@ public static void M1(this string s) { }
     public static int M2(this string s) => s.Length;
 }
 
-// semmle-extractor-options: /r:System.Linq.dll
+// semmle-extractor-options: /r:System.Linq.dll /r:System.Drawing.Primitives.dll

csharp/ql/test/query-tests/Nullness/NullCheck.expected

@@ -276,6 +276,10 @@
 | E.cs:384:13:384:22 | ... == ... | E.cs:384:13:384:14 | access to parameter e1 | true | true |
 | E.cs:384:27:384:36 | ... == ... | E.cs:384:27:384:28 | access to parameter e2 | false | false |
 | E.cs:384:27:384:36 | ... == ... | E.cs:384:27:384:28 | access to parameter e2 | true | true |
+| E.cs:391:9:391:9 | access to parameter i | E.cs:391:9:391:9 | access to parameter i | non-null | false |
+| E.cs:391:9:391:9 | access to parameter i | E.cs:391:9:391:9 | access to parameter i | null | true |
+| E.cs:397:9:397:13 | access to parameter color | E.cs:397:9:397:13 | access to parameter color | non-null | false |
+| E.cs:397:9:397:13 | access to parameter color | E.cs:397:9:397:13 | access to parameter color | null | true |
 | Forwarding.cs:9:14:9:30 | call to method IsNullOrEmpty | Forwarding.cs:9:14:9:14 | access to local variable s | false | false |
 | Forwarding.cs:14:13:14:32 | call to method IsNotNullOrEmpty | Forwarding.cs:14:13:14:13 | access to local variable s | true | false |
 | Forwarding.cs:19:14:19:23 | call to method IsNull | Forwarding.cs:19:14:19:14 | access to local variable s | false | false |

csharp/ql/test/query-tests/Nullness/NullMaybe.expected

@@ -370,6 +370,10 @@ nodes
 | E.cs:384:27:384:28 | access to parameter e2 |
 | E.cs:386:16:386:17 | access to parameter e1 |
 | E.cs:386:27:386:28 | access to parameter e2 |
+| E.cs:391:9:391:15 | SSA def(i) |
+| E.cs:392:16:392:16 | access to parameter i |
+| E.cs:397:9:397:44 | SSA def(color) |
+| E.cs:398:16:398:20 | access to parameter color |
 | Forwarding.cs:7:16:7:23 | SSA def(s) |
 | Forwarding.cs:14:9:17:9 | if (...) ... |
 | Forwarding.cs:19:9:22:9 | if (...) ... |
@@ -719,6 +723,8 @@ edges
 | E.cs:384:9:385:24 | if (...) ... | E.cs:384:27:384:28 | access to parameter e2 |
 | E.cs:384:9:385:24 | if (...) ... | E.cs:386:27:386:28 | access to parameter e2 |
 | E.cs:384:27:384:28 | access to parameter e2 | E.cs:386:16:386:17 | access to parameter e1 |
+| E.cs:391:9:391:15 | SSA def(i) | E.cs:392:16:392:16 | access to parameter i |
+| E.cs:397:9:397:44 | SSA def(color) | E.cs:398:16:398:20 | access to parameter color |
 | Forwarding.cs:7:16:7:23 | SSA def(s) | Forwarding.cs:14:9:17:9 | if (...) ... |
 | Forwarding.cs:14:9:17:9 | if (...) ... | Forwarding.cs:19:9:22:9 | if (...) ... |
 | Forwarding.cs:19:9:22:9 | if (...) ... | Forwarding.cs:24:9:27:9 | if (...) ... |
@@ -827,6 +833,8 @@ edges
 | E.cs:386:27:386:28 | access to parameter e2 | E.cs:380:30:380:31 | SSA param(e2) | E.cs:386:27:386:28 | access to parameter e2 | Variable $@ may be null here as suggested by $@ null check. | E.cs:380:30:380:31 | e2 | e2 | E.cs:382:28:382:37 | ... != ... | this |
 | E.cs:386:27:386:28 | access to parameter e2 | E.cs:380:30:380:31 | SSA param(e2) | E.cs:386:27:386:28 | access to parameter e2 | Variable $@ may be null here as suggested by $@ null check. | E.cs:380:30:380:31 | e2 | e2 | E.cs:382:58:382:67 | ... == ... | this |
 | E.cs:386:27:386:28 | access to parameter e2 | E.cs:380:30:380:31 | SSA param(e2) | E.cs:386:27:386:28 | access to parameter e2 | Variable $@ may be null here as suggested by $@ null check. | E.cs:380:30:380:31 | e2 | e2 | E.cs:384:27:384:36 | ... == ... | this |
+| E.cs:392:16:392:16 | access to parameter i | E.cs:391:9:391:15 | SSA def(i) | E.cs:392:16:392:16 | access to parameter i | Variable $@ may be null here because it has a nullable type. | E.cs:389:19:389:19 | i | i | E.cs:389:19:389:19 | i | this |
+| E.cs:398:16:398:20 | access to parameter color | E.cs:397:9:397:44 | SSA def(color) | E.cs:398:16:398:20 | access to parameter color | Variable $@ may be null here because it has a nullable type. | E.cs:395:53:395:57 | color | color | E.cs:395:53:395:57 | color | this |
 | GuardedString.cs:35:31:35:31 | access to local variable s | GuardedString.cs:7:16:7:32 | SSA def(s) | GuardedString.cs:35:31:35:31 | access to local variable s | Variable $@ may be null here because of $@ assignment. | GuardedString.cs:7:16:7:16 | s | s | GuardedString.cs:7:16:7:32 | String s = ... | this |
 | NullMaybeBad.cs:7:27:7:27 | access to parameter o | NullMaybeBad.cs:13:17:13:20 | null | NullMaybeBad.cs:7:27:7:27 | access to parameter o | Variable $@ may be null here because of $@ null argument. | NullMaybeBad.cs:5:25:5:25 | o | o | NullMaybeBad.cs:13:17:13:20 | null | this |
 | StringConcatenation.cs:16:17:16:17 | access to local variable s | StringConcatenation.cs:14:16:14:23 | SSA def(s) | StringConcatenation.cs:16:17:16:17 | access to local variable s | Variable $@ may be null here because of $@ assignment. | StringConcatenation.cs:14:16:14:16 | s | s | StringConcatenation.cs:14:16:14:23 | String s = ... | this |