From 611972f672bb1258d15571bec28f1a53692f56b7 Mon Sep 17 00:00:00 2001
From: cpovirk <cpovirk@google.com>
Date: Mon, 13 Oct 2025 13:21:03 -0700
Subject: [PATCH] Suppress or address errors from a forthcoming Error Prone
 check that looks for calls like `containsExactly(null)` that always throw
 NPE.

(To check for a list that contains only a null element, the calls will soon need to be `containsExactly((Object) null)` (with a cast to the array's _element_ type), not `containsExactly(null)` or `containsExactly((Object[]) null)` (with a cast to the _array_ type).)

Also, sidestep other null-varargs fun by using `Collections.singleton` instead of the varargs methods `Arrays.asList` and `Stream.of`.)

([the check](https://github.com/google/error-prone/pull/5263))

PiperOrigin-RevId: 818803000
---
 .../java/com/google/common/truth/IterableSubjectTest.java  | 7 +++++--
 .../java/com/google/common/truth/StreamSubjectTest.java    | 6 +++++-
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/core/src/test/java/com/google/common/truth/IterableSubjectTest.java b/core/src/test/java/com/google/common/truth/IterableSubjectTest.java
index 71254721c..8f012a2f1 100644
--- a/core/src/test/java/com/google/common/truth/IterableSubjectTest.java
+++ b/core/src/test/java/com/google/common/truth/IterableSubjectTest.java
@@ -23,6 +23,7 @@
 import static com.google.common.truth.Truth.assertThat;
 import static java.lang.String.CASE_INSENSITIVE_ORDER;
 import static java.util.Arrays.asList;
+import static java.util.Collections.singleton;
 import static org.junit.Assert.assertThrows;
 
 import com.google.common.collect.ImmutableList;
@@ -814,10 +815,12 @@ public void containsExactlyWithDuplicatesOutOfOrder() {
   }
 
   @Test
+  // We intentionally test the behavior of the method under a call that will soon fail.
+  @SuppressWarnings("NullNeedsCastForVarargs")
   @J2ktIncompatible // Kotlin can't pass a null array for a varargs parameter
   public void containsExactlyWithOnlyNullPassedAsNullArray() {
-    // Truth is tolerant of this erroneous varargs call.
-    Iterable<Object> actual = asList((Object) null);
+    Iterable<Object> actual = singleton(null);
+    // We are changing Truth from tolerating this erroneous varargs call to not tolerating it.
     try {
       assertThat(actual).containsExactly((Object[]) null);
     } catch (NullPointerException e) {
diff --git a/core/src/test/java/com/google/common/truth/StreamSubjectTest.java b/core/src/test/java/com/google/common/truth/StreamSubjectTest.java
index 9ce30bcce..d2b1c260d 100644
--- a/core/src/test/java/com/google/common/truth/StreamSubjectTest.java
+++ b/core/src/test/java/com/google/common/truth/StreamSubjectTest.java
@@ -21,6 +21,7 @@
 import static com.google.common.truth.FailureAssertions.assertFailureValue;
 import static com.google.common.truth.Truth.assertThat;
 import static java.util.Arrays.asList;
+import static java.util.Collections.singleton;
 
 import java.util.stream.Stream;
 import org.junit.Test;
@@ -316,8 +317,11 @@ public void containsExactly_nullObject() {
 
   @Test
   @J2ktIncompatible // Kotlin can't pass a null array for a varargs parameter
+  // We intentionally test the behavior of the method under a call that will soon fail.
+  @SuppressWarnings("NullNeedsCastForVarargs")
   public void containsExactly_nullObjectArray() {
-    StreamSubject subject = assertThat(Stream.of((Object) null));
+    StreamSubject subject = assertThat(singleton(null).stream());
+    // We are changing Truth from tolerating this erroneous varargs call to not tolerating it.
     try {
       subject.containsExactly((Object[]) null);
     } catch (NullPointerException e) {