C#: Add nullness test using an as expression

hvitved · hvitved · commit ccda1c8d3d72 · 2018-12-20T14:54:48.000+01:00
diff --git a/csharp/ql/test/query-tests/Nullness/E.cs b/csharp/ql/test/query-tests/Nullness/E.cs
@@ -296,6 +296,12 @@ public void Ex24(bool b)
         }
     }
 
+    public void Ex25(object o)
+    {
+        var s = o as string;
+        s.ToString(); // BAD (maybe) (false negative)
+    }
+
     public bool Field;
     string Make() => Field ? null : "";
 }
diff --git a/csharp/ql/test/query-tests/Nullness/Implications.expected b/csharp/ql/test/query-tests/Nullness/Implications.expected
@@ -1468,10 +1468,14 @@
 | E.cs:293:15:293:19 | call to method M2 | null | E.cs:293:13:293:13 | access to local variable s | null |
 | E.cs:295:13:295:13 | access to local variable s | non-null | E.cs:292:20:292:32 | ... ? ... : ... | non-null |
 | E.cs:295:13:295:13 | access to local variable s | null | E.cs:292:20:292:32 | ... ? ... : ... | null |
-| E.cs:300:22:300:38 | ... ? ... : ... | non-null | E.cs:300:22:300:26 | access to field Field | false |
-| E.cs:300:22:300:38 | ... ? ... : ... | non-null | E.cs:300:37:300:38 | "" | non-null |
-| E.cs:300:22:300:38 | ... ? ... : ... | null | E.cs:300:22:300:26 | access to field Field | true |
-| E.cs:300:22:300:38 | ... ? ... : ... | null | E.cs:300:30:300:33 | null | null |
+| E.cs:301:13:301:27 | String s = ... | non-null | E.cs:301:13:301:13 | access to local variable s | non-null |
+| E.cs:301:13:301:27 | String s = ... | null | E.cs:301:13:301:13 | access to local variable s | null |
+| E.cs:302:9:302:9 | access to local variable s | non-null | E.cs:301:17:301:27 | ... as ... | non-null |
+| E.cs:302:9:302:9 | access to local variable s | null | E.cs:301:17:301:27 | ... as ... | null |
+| E.cs:306:22:306:38 | ... ? ... : ... | non-null | E.cs:306:22:306:26 | access to field Field | false |
+| E.cs:306:22:306:38 | ... ? ... : ... | non-null | E.cs:306:37:306:38 | "" | non-null |
+| E.cs:306:22:306:38 | ... ? ... : ... | null | E.cs:306:22:306:26 | access to field Field | true |
+| E.cs:306:22:306:38 | ... ? ... : ... | null | E.cs:306:30:306:33 | null | null |
 | Forwarding.cs:7:16:7:23 | String s = ... | non-null | Forwarding.cs:7:16:7:16 | access to local variable s | non-null |
 | Forwarding.cs:7:16:7:23 | String s = ... | null | Forwarding.cs:7:16:7:16 | access to local variable s | null |
 | Forwarding.cs:9:13:9:30 | !... | false | Forwarding.cs:9:14:9:30 | call to method IsNullOrEmpty | true |

Original file line number	Diff line number	Diff line change
`@@ -296,6 +296,12 @@ public void Ex24(bool b)`
`296`	`296`	`}`
`297`	`297`	`}`
`298`	`298`
	`299`	`+ public void Ex25(object o)`
	`300`	`+ {`
	`301`	`+ var s = o as string;`
	`302`	`+ s.ToString(); // BAD (maybe) (false negative)`
	`303`	`+ }`
	`304`	`+`
`299`	`305`	`public bool Field;`
`300`	`306`	`string Make() => Field ? null : "";`
`301`	`307`	`}`