Clean up string representations for unknown objects

Don't call the `toString` method on unknown objects as it potentially
breaks hermeticity and determinism. Use a generic string like
"<unknown object package.ClassName>" instead.

PiperOrigin-RevId: 161970449

1 files changed, 11 insertions, 0 deletions

diff --git a/src/test/java/com/google/devtools/build/lib/skylark/SkylarkStringRepresentationsTest.java b/src/test/java/com/google/devtools/build/lib/skylark/SkylarkStringRepresentationsTest.java
index 82e2dfed90..8db33169eb 100644
--- a/src/test/java/com/google/devtools/build/lib/skylark/SkylarkStringRepresentationsTest.java
+++ b/src/test/java/com/google/devtools/build/lib/skylark/SkylarkStringRepresentationsTest.java
@@ -389,6 +389,17 @@ public class SkylarkStringRepresentationsTest extends SkylarkTestCase {
   }
 
   @Test
+  public void testStringRepresentationsOfUnknownObjects() throws Exception {
+    update("mock", new Object());
+
+    assertThat(eval("str(mock)")).isEqualTo("<unknown object java.lang.Object>");
+    assertThat(eval("repr(mock)")).isEqualTo("<unknown object java.lang.Object>");
+    assertThat(eval("'{}'.format(mock)")).isEqualTo("<unknown object java.lang.Object>");
+    assertThat(eval("'%s' % mock")).isEqualTo("<unknown object java.lang.Object>");
+    assertThat(eval("'%r' % mock")).isEqualTo("<unknown object java.lang.Object>");
+  }
+
+  @Test
   public void testLegacyStringRepresentations_Labels() throws Exception {
     setSkylarkSemanticsOptions("--incompatible_descriptive_string_representations=false");