C#: Add some more tests.

Author: michaelnebel

csharp/ql/test/library-tests/dataflow/nullness/MaybeNullExpr.cs

@@ -17,5 +17,8 @@ void M(object o, bool b)
 
         // Conditional access might be null as the qualifier might be null.
         var s1 = (o as C)?.Prop;
+
+        // Conditional access might be null as the qualifier might be null.
+        var i = o?.GetHashCode();
     }
 }

csharp/ql/test/library-tests/dataflow/nullness/maybeNullExpr.expected

@@ -5,3 +5,4 @@
 | MaybeNullExpr.cs:16:17:16:22 | ... as ... |
 | MaybeNullExpr.cs:19:18:19:31 | access to property Prop |
 | MaybeNullExpr.cs:19:19:19:24 | ... as ... |
+| MaybeNullExpr.cs:22:17:22:32 | call to method GetHashCode |

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

@@ -0,0 +1,11 @@
+using System;
+using System.ComponentModel;
+
+class ConditionalAccessTest
+{
+    void M1(object o)
+    {
+        var t = o?.GetType();
+        Console.WriteLine(t.FullName); // $ Alert[cs/dereferenced-value-may-be-null]
+    }
+}

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

@@ -51,6 +51,7 @@
 | C.cs:229:22:229:30 | ... != ... | C.cs:229:22:229:22 | access to local variable s |
 | C.cs:235:24:235:32 | ... == ... | C.cs:235:24:235:24 | access to local variable s |
 | C.cs:235:24:235:32 | ... == ... | C.cs:235:29:235:32 | null |
+| ConditionalAccess.cs:8:17:8:17 | access to parameter o | ConditionalAccess.cs:8:17:8:17 | access to parameter o |
 | D.cs:28:13:28:25 | ... != ... | D.cs:28:13:28:17 | access to parameter param |
 | D.cs:38:13:38:21 | ... == ... | D.cs:38:13:38:13 | access to parameter x |
 | D.cs:39:16:39:24 | ... == ... | D.cs:39:16:39:16 | access to parameter x |

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

@@ -6,6 +6,7 @@
 | C.cs:203:13:203:13 | access to local variable s | Variable $@ may be null at this access because of $@ assignment. | C.cs:185:13:185:13 | s | s | C.cs:204:13:204:20 | ... = ... | this |
 | C.cs:223:9:223:9 | access to local variable s | Variable $@ may be null at this access because of $@ assignment. | C.cs:210:13:210:13 | s | s | C.cs:222:13:222:20 | ... = ... | this |
 | C.cs:242:13:242:13 | access to local variable s | Variable $@ may be null at this access because of $@ assignment. | C.cs:228:16:228:16 | s | s | C.cs:240:24:240:31 | ... = ... | this |
+| ConditionalAccess.cs:9:27:9:27 | access to local variable t | Variable $@ may be null at this access because of $@ assignment. | ConditionalAccess.cs:8:13:8:13 | t | t | ConditionalAccess.cs:8:13:8:28 | Type t = ... | this |
 | D.cs:23:9:23:13 | access to parameter param | Variable $@ may be null at this access because of $@ null argument. | D.cs:21:32:21:36 | param | param | D.cs:17:17:17:20 | null | this |
 | D.cs:32:9:32:13 | access to parameter param | Variable $@ may be null at this access as suggested by $@ null check. | D.cs:26:32:26:36 | param | param | D.cs:28:13:28:25 | ... != ... | this |
 | D.cs:73:13:73:14 | access to local variable o7 | Variable $@ may be null at this access because of $@ assignment. | D.cs:68:13:68:14 | o7 | o7 | D.cs:68:13:68:34 | String o7 = ... | this |