Add unit tests to capture some current behavior around ReferenceCollector.isWellDefined.

PiperOrigin-RevId: 788983162

Author: gkdn

test/com/google/javascript/jscomp/ReferenceCollectorTest.java

@@ -97,6 +97,57 @@ public void testObjectRest_declaration() {
         });
   }
 
+  @Test
+  public void testClass() {
+    testBehavior(
+        """
+        class Foo {}
+        """,
+        (NodeTraversal t, ReferenceMap rm) -> {
+          if (t.getScope().isGlobal()) {
+            ReferenceCollection x = rm.getReferences(t.getScope().getVar("Foo"));
+
+            assertThat(x.isAssignedOnceInLifetime()).isTrue();
+            assertThat(x.isWellDefined()).isTrue();
+            assertThat(x).comparingElementsUsing(IS_DECLARATION).containsExactly(true).inOrder();
+          }
+        });
+  }
+
+  @Test
+  public void testClass_withPrototype() {
+    testBehavior(
+        """
+        class Foo {}
+        Foo.prototype.bar = 1;
+        """,
+        (NodeTraversal t, ReferenceMap rm) -> {
+          if (t.getScope().isGlobal()) {
+            ReferenceCollection x = rm.getReferences(t.getScope().getVar("Foo"));
+
+            assertThat(x.isAssignedOnceInLifetime()).isTrue();
+            assertThat(x.isWellDefined()).isFalse(); // TODO(b/435019132): Should be true.
+          }
+        });
+  }
+
+  @Test
+  public void testClass_referencedAfterDeclaration() {
+    testBehavior(
+        """
+        class Foo {}
+        const x = Foo;
+        """,
+        (NodeTraversal t, ReferenceMap rm) -> {
+          if (t.getScope().isGlobal()) {
+            ReferenceCollection x = rm.getReferences(t.getScope().getVar("Foo"));
+
+            assertThat(x.isAssignedOnceInLifetime()).isTrue();
+            assertThat(x.isWellDefined()).isFalse(); // TODO(b/435019132): Should be true.
+          }
+        });
+  }
+
   @Test
   public void testImport1() {
     testBehavior(