[nullsafe] Make intention of NullFieldAccess test explicit and add positive cases

Summary:
Get rid of helper class `C`, normal Object serves the same goal well
Don't return values from a function, focus only on nullable
dereferences.

Reviewed By: jberdine

Differential Revision: D17314569

fbshipit-source-id: d70e66b5f

infer/tests/codetoanalyze/java/nullsafe-default/NullFieldAccess.java

@@ -10,49 +10,58 @@ package codetoanalyze.java.nullsafe_default;
 import javax.annotation.Nullable;
 
 public class NullFieldAccess {
-  class C {
-    int n;
-  }
 
   interface I {
-    @Nullable C c = null;
+    @Nullable Object nullable = new Object();
+    Object notNull = new Object();
   }
 
-  @Nullable C x;
+  @Nullable Object nullable;
-  C y;
+  Object notNull;
-  static final @Nullable C z = null;
+
+  static final @Nullable Object nullableStatic = new Object();
+  static final Object notNullStatic = new Object();
+
+  @Nullable Object[] nullableArray;
+  Object[] notNullArray;
 
   NullFieldAccess() {
-    y = new C();
+    nullable = new Object();
+    notNull = new Object();
+    nullableArray = new Object[1];
+    notNullArray = new Object[1];
   }
 
-  int useX() {
+  void testNonStaticFields() {
-    C c = x;
+    Object bad = nullable;
-    return c.n;
+    bad.toString(); // BAD: `bad` can be null
-  }
 
-  int useY() {
+    Object good = notNull;
-    C c = y;
+    good.toString(); // OK: `good` is not null
-    return c.n;
   }
 
-  int useZ() {
+  void testStatic() {
-    C c = z;
+    Object bad = nullableStatic;
-    return c.n;
+    bad.toString(); // BAD: `bad` can be null
-  }
 
-  int useInterface(I i) {
+    Object good = notNullStatic;
-    C c = i.c;
+    good.toString(); // OK: `good` is not null
-    return c.n;
   }
 
-  @Nullable Object[] objects;
+  void testInterface() {
+    Object bad = I.nullable;
+    bad.toString(); // BAD: `bad` can be null
 
-  int arrayLength() {
+    Object good = I.notNull;
-    return objects.length;
+    good.toString(); // OK: `good` is not null
   }
 
-  Object arrayAccess() {
+  void testArray() {
-    return objects[0];
+    int i1 = nullableArray.length; // BAD: array can be null
+    Object o1 = nullableArray[0]; // BAD: array can be null
+
+    int i2 = notNullArray.length; // OK: arrays is not null
+    Object o2 = notNullArray[0]; // OK: array is not null
   }
+
 }

infer/tests/codetoanalyze/java/nullsafe-default/issues.exp

@@ -102,11 +102,11 @@ codetoanalyze/java/nullsafe-default/NestedFieldAccess.java, codetoanalyze.java.n
 codetoanalyze/java/nullsafe-default/NestedFieldAccess.java, codetoanalyze.java.nullsafe_default.NestedFieldAccess$TestNullableChains.param_AccessWithoutNullCheckIsBad(codetoanalyze.java.nullsafe_default.NestedFieldAccess$C):void, 1, ERADICATE_NULLABLE_DEREFERENCE, no_bucket, WARNING, [The value of `c.s` in the call to `length()` is nullable and is not locally checked for null. (Origin: field NestedFieldAccess$C.s at line 65)]
 codetoanalyze/java/nullsafe-default/NestedFieldAccess.java, codetoanalyze.java.nullsafe_default.NestedFieldAccess$TestNullableChains.veryDeep_AccessWithoutNullCheckIsBad(codetoanalyze.java.nullsafe_default.NestedFieldAccess$CCC):void, 2, ERADICATE_NULLABLE_DEREFERENCE, no_bucket, WARNING, [The value of `ccc.cc.c.s` in the call to `length()` is nullable and is not locally checked for null. (Origin: field NestedFieldAccess$C.s at line 100)]
 codetoanalyze/java/nullsafe-default/NestedFieldAccess.java, codetoanalyze.java.nullsafe_default.NestedFieldAccess$TestNullableChains.veryDeep_IncompleteAccessViaOrEarlyReturnIsBad(codetoanalyze.java.nullsafe_default.NestedFieldAccess$CCC):void, 3, ERADICATE_NULLABLE_DEREFERENCE, no_bucket, WARNING, [The value of `ccc.cc.c.s` in the call to `length()` is nullable and is not locally checked for null. (Origin: field NestedFieldAccess$C.s at line 114)]
-codetoanalyze/java/nullsafe-default/NullFieldAccess.java, codetoanalyze.java.nullsafe_default.NullFieldAccess.arrayAccess():java.lang.Object, 1, ERADICATE_NULLABLE_DEREFERENCE, no_bucket, WARNING, [Object `NullFieldAccess.objects` is nullable and is not locally checked for null when accessing element at index `0`. (Origin: field NullFieldAccess.objects at line 56)]
+codetoanalyze/java/nullsafe-default/NullFieldAccess.java, codetoanalyze.java.nullsafe_default.NullFieldAccess.testArray():void, 1, ERADICATE_NULLABLE_DEREFERENCE, no_bucket, WARNING, [Object `NullFieldAccess.nullableArray` is nullable and is not locally checked for null when accessing field `length`. (Origin: field NullFieldAccess.nullableArray at line 60)]
-codetoanalyze/java/nullsafe-default/NullFieldAccess.java, codetoanalyze.java.nullsafe_default.NullFieldAccess.arrayLength():int, 1, ERADICATE_NULLABLE_DEREFERENCE, no_bucket, WARNING, [Object `NullFieldAccess.objects` is nullable and is not locally checked for null when accessing field `length`. (Origin: field NullFieldAccess.objects at line 52)]
+codetoanalyze/java/nullsafe-default/NullFieldAccess.java, codetoanalyze.java.nullsafe_default.NullFieldAccess.testArray():void, 2, ERADICATE_NULLABLE_DEREFERENCE, no_bucket, WARNING, [Object `NullFieldAccess.nullableArray` is nullable and is not locally checked for null when accessing element at index `0`. (Origin: field NullFieldAccess.nullableArray at line 60)]
-codetoanalyze/java/nullsafe-default/NullFieldAccess.java, codetoanalyze.java.nullsafe_default.NullFieldAccess.useInterface(codetoanalyze.java.nullsafe_default.NullFieldAccess$I):int, 2, ERADICATE_NULLABLE_DEREFERENCE, no_bucket, WARNING, [Object `c` is nullable and is not locally checked for null when accessing field `NullFieldAccess$C.n`. (Origin: field NullFieldAccess$I.c at line 45)]
+codetoanalyze/java/nullsafe-default/NullFieldAccess.java, codetoanalyze.java.nullsafe_default.NullFieldAccess.testInterface():void, 2, ERADICATE_NULLABLE_DEREFERENCE, no_bucket, WARNING, [The value of `bad` in the call to `toString()` is nullable and is not locally checked for null. (Origin: field NullFieldAccess$I.nullable at line 52)]
-codetoanalyze/java/nullsafe-default/NullFieldAccess.java, codetoanalyze.java.nullsafe_default.NullFieldAccess.useX():int, 2, ERADICATE_NULLABLE_DEREFERENCE, no_bucket, WARNING, [Object `c` is nullable and is not locally checked for null when accessing field `NullFieldAccess$C.n`. (Origin: field NullFieldAccess.x at line 30)]
+codetoanalyze/java/nullsafe-default/NullFieldAccess.java, codetoanalyze.java.nullsafe_default.NullFieldAccess.testNonStaticFields():void, 2, ERADICATE_NULLABLE_DEREFERENCE, no_bucket, WARNING, [The value of `bad` in the call to `toString()` is nullable and is not locally checked for null. (Origin: field NullFieldAccess.nullable at line 36)]
-codetoanalyze/java/nullsafe-default/NullFieldAccess.java, codetoanalyze.java.nullsafe_default.NullFieldAccess.useZ():int, 2, ERADICATE_NULLABLE_DEREFERENCE, no_bucket, WARNING, [Object `c` is nullable and is not locally checked for null when accessing field `NullFieldAccess$C.n`. (Origin: field NullFieldAccess.z at line 40)]
+codetoanalyze/java/nullsafe-default/NullFieldAccess.java, codetoanalyze.java.nullsafe_default.NullFieldAccess.testStatic():void, 2, ERADICATE_NULLABLE_DEREFERENCE, no_bucket, WARNING, [The value of `bad` in the call to `toString()` is nullable and is not locally checked for null. (Origin: field NullFieldAccess.nullableStatic at line 44)]
 codetoanalyze/java/nullsafe-default/NullMethodCall.java, codetoanalyze.java.nullsafe_default.NullMethodCall$Inner.outerField():int, 2, ERADICATE_NULLABLE_DEREFERENCE, no_bucket, WARNING, [The value of `s` in the call to `length()` is nullable and is not locally checked for null. (Origin: field NullMethodCall.fld at line 69)]
 codetoanalyze/java/nullsafe-default/NullMethodCall.java, codetoanalyze.java.nullsafe_default.NullMethodCall$Inner.outerPrivateField():int, 2, ERADICATE_NULLABLE_DEREFERENCE, no_bucket, WARNING, [The value of `s` in the call to `length()` is nullable and is not locally checked for null. (Origin: field NullMethodCall.pfld at line 80)]
 codetoanalyze/java/nullsafe-default/NullMethodCall.java, codetoanalyze.java.nullsafe_default.NullMethodCall.FP_propagatesNonNullAfterComparisonFieldOkay(java.lang.Object):void, 2, ERADICATE_NULLABLE_DEREFERENCE, no_bucket, WARNING, [The value of `NullMethodCall.nullableField` in the call to `toString()` is nullable and is not locally checked for null. (Origin: field NullMethodCall.nullableField at line 275)]