C#: Add more tests for cs/useless-assignment-to-local

Author: hvitved

csharp/ql/test/query-tests/Dead Code/DeadStoreOfLocal/DeadStoreOfLocal.cs

@@ -389,6 +389,20 @@ string M7(bool b)
             return s;
         return null;
     }
+
+    string M8()
+    {
+        string s = default; // "GOOD"
+        s = "";
+        return s;
+    }
+
+    string M9()
+    {
+        var s = (string)null; // "GOOD"
+        s = "";
+        return s;
+    }
 }
 
 class Anonymous

csharp/ql/test/query-tests/Dead Code/DeadStoreOfLocal/DeadStoreOfLocal.expected

@@ -16,6 +16,8 @@
 | DeadStoreOfLocal.cs:320:9:320:32 | ... = ... | This assignment to $@ is useless, since its value is never read. | DeadStoreOfLocal.cs:316:23:316:23 | b | b |
 | DeadStoreOfLocal.cs:361:13:361:20 | String s = ... | This assignment to $@ is useless, since its value is never read. | DeadStoreOfLocal.cs:361:13:361:13 | s | s |
 | DeadStoreOfLocal.cs:387:13:387:21 | ... = ... | This assignment to $@ is useless, since its value is never read. | DeadStoreOfLocal.cs:385:13:385:13 | s | s |
+| DeadStoreOfLocal.cs:395:16:395:26 | String s = ... | This assignment to $@ is useless, since its value is never read. | DeadStoreOfLocal.cs:395:16:395:16 | s | s |
+| DeadStoreOfLocal.cs:402:13:402:28 | String s = ... | This assignment to $@ is useless, since its value is never read. | DeadStoreOfLocal.cs:402:13:402:13 | s | s |
 | DeadStoreOfLocalBad.cs:7:13:7:48 | Boolean success = ... | This assignment to $@ is useless, since its value is never read. | DeadStoreOfLocalBad.cs:7:13:7:19 | success | success |
 | DeadStoreOfLocalBad.cs:23:32:23:32 | FormatException e | This assignment to $@ is useless, since its value is never read. | DeadStoreOfLocalBad.cs:23:32:23:32 | e | e |
 | DeadStoreOfLocalBad.cs:32:22:32:22 | String s | This assignment to $@ is useless, since its value is never read. | DeadStoreOfLocalBad.cs:32:22:32:22 | s | s |