Add example of lazy dynamic dispatch calling a method from the interface

Summary: Example of dynamic dispatch with interfaces were already working. Adding some tests now so that we don't break this.

Reviewed By: sblackshear

Differential Revision: D3220360

fb-gh-sync-id: 11395dd
fbshipit-source-id: 11395dd

infer/tests/codetoanalyze/java/tracing/LazyDynamicDispatchExample.java

@@ -9,7 +9,11 @@
 
 package codetoanalyze.java.tracing;
 
-class A {
+interface I {
+  T get();
+}
+
+class A implements I {
 
   public T get() {
     return new T();
@@ -17,7 +21,7 @@ class A {
 
 }
 
-class B extends A  {
+class B extends A {
 
   public T get() {
     return null;
@@ -27,13 +31,27 @@ class B extends A  {
 
 public class LazyDynamicDispatchExample {
 
-  static T foo(A a) {
+  static T fromSupertype(A a) {
     return a.get();
   }
 
-  static void bar() {
+  static T fromInterface(I i) {
+    return i.get();
+  }
+
+  static void callWithSubtype() {
+    B b = new B();
+    fromSupertype(b).f();
+  }
+
+  static void shouldNotReportLocalVarTypeIsKnown() {
+    A a = new A();
+    fromInterface(a).f();
+  }
+
+  static void shouldReportLocalVarTypeIsKnown() {
     B b = new B();
-    foo(b).f();
+    fromInterface(b).f();
   }
 
 }

infer/tests/endtoend/java/tracing/LazyDynamicDispatchTest.java

@@ -42,7 +42,8 @@ public class LazyDynamicDispatchTest {
   public void matchErrors()
       throws IOException, InterruptedException, InferException {
     String[] methods = {
-        "bar"
+        "callWithSubtype",
+        "shouldReportLocalVarTypeIsKnown",
     };
     assertThat(
         "Results should contain " + NPE,