Add unit test for collapse properties issue

TS 5.2 starts outputing code in a shape that causes a bad property collapse.

This change adds a unit test for InlineAndCollapseProperties that mimics
a previously-added reproduction of this problem in an integration test.

At the moment the unit test added by this change doesn't successfully reproduce
the issue, but I'd like to check it in anyway as a step in the investigation.

The next step is to figure out why a different decision is being made
by InlineAndCollapseProperties in this unit test vs the integration test case
that does reproduce the problem.

PiperOrigin-RevId: 588533168

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

@@ -20,9 +20,11 @@
 import static com.google.javascript.jscomp.InlineAndCollapseProperties.RECEIVER_AFFECTED_BY_COLLAPSE;
 import static com.google.javascript.rhino.testing.NodeSubject.assertNode;
 
+import com.google.common.collect.ImmutableList;
 import com.google.javascript.jscomp.CompilerOptions.ChunkOutputType;
 import com.google.javascript.jscomp.CompilerOptions.PropertyCollapseLevel;
 import com.google.javascript.jscomp.deps.ModuleLoader.ResolutionMode;
+import com.google.javascript.jscomp.testing.TestExternsBuilder;
 import com.google.javascript.rhino.Node;
 import com.google.javascript.rhino.testing.NodeSubject;
 import org.junit.Before;
@@ -111,6 +113,96 @@ public void testTs52OutputChange() {
                 "")));
   }
 
+  @Test
+  public void testTs52OutputChangeVariableReassignment() {
+    // This test case was created by executing
+    // AdvancedOptimizationsIntegrationTest#testTSVariableReassignmentAndAliasingDueToDecoration
+    // with `options.setPrintSourceAfterEachPass(true)`.
+    // The input source here is how the source code looks at the point just before
+    // InlineAndCollapseProperties runs in that test case.
+    test(
+        externs(
+            ImmutableList.of(
+                new TestExternsBuilder()
+                    .addObject()
+                    .addConsole()
+                    .addClosureExterns()
+                    .addExtra(
+                        // simulate "const tslib_1 = goog.require('tslib');",
+                        lines(
+                            "var tslib_1 = {", //
+                            "  __decorate: function(decorators, clazz) {}",
+                            "};"))
+                    .buildExternsFile("externs.js"))),
+        srcs(
+            lines(
+                "var module$exports$main = {};", //
+                "var module$contents$main_module =",
+                "    module$contents$main_module || {id: 'main.ts'};",
+                "var module$contents$main_Foo_1;",
+                "function module$contents$main_noopDecorator(arg) {",
+                "  return arg;",
+                "}",
+                "var i0$classdecl$var0 = function() {};",
+                "i0$classdecl$var0.foo = function() {",
+                "  console.log('Hello');",
+                "};",
+                "i0$classdecl$var0.prototype.bar = function() {",
+                "  module$contents$main_Foo_1.foo();",
+                "  console.log('ID: ' + module$contents$main_Foo_1.ID + '');",
+                "};",
+                "var module$contents$main_Foo = module$contents$main_Foo_1 = i0$classdecl$var0;",
+                "module$contents$main_Foo.ID = 'original';",
+                "module$contents$main_Foo.ID2 = module$contents$main_Foo_1.ID;",
+                "(function() {",
+                "module$contents$main_Foo_1.foo();",
+                "console.log('ID: ' + module$contents$main_Foo_1.ID + '');",
+                "})();",
+                "module$contents$main_Foo = module$contents$main_Foo_1 = tslib_1.__decorate(",
+                "    [module$contents$main_noopDecorator], module$contents$main_Foo);",
+                "if (false) {",
+                "  module$contents$main_Foo.ID;",
+                "  module$contents$main_Foo.ID2;",
+                "}",
+                "(new module$contents$main_Foo()).bar();")),
+        expected(
+            lines(
+                "var module$contents$main_module =", //
+                "    module$contents$main_module || {id: 'main.ts'};",
+                "var module$contents$main_Foo_1;",
+                "function module$contents$main_noopDecorator(arg) {",
+                "  return arg;",
+                "}",
+                "var i0$classdecl$var0 = function() {};",
+                // TODO : b/299055739 - This unit test doesn't reproduce the problem we want to fix.
+                // In the AdvancedOptimizationsIntegrationTest test case
+                // `.foo` gets collapsed, which breaks this code.
+                // Why doesn't that happen in this unit test case?
+                // This one line is the only difference
+                "i0$classdecl$var0.foo = function() {",
+                // "var i0$classdecl$var0$foo = function() {",
+                "  console.log('Hello');",
+                "};",
+                "i0$classdecl$var0.prototype.bar = function() {",
+                "  module$contents$main_Foo_1.foo();",
+                "  console.log('ID: ' + module$contents$main_Foo_1.ID + '');",
+                "};",
+                "var module$contents$main_Foo = module$contents$main_Foo_1 = i0$classdecl$var0;",
+                "module$contents$main_Foo.ID = 'original';",
+                "module$contents$main_Foo.ID2 = module$contents$main_Foo_1.ID;",
+                "(function() {",
+                "module$contents$main_Foo_1.foo();",
+                "console.log('ID: ' + module$contents$main_Foo_1.ID + '');",
+                "})();",
+                "module$contents$main_Foo = module$contents$main_Foo_1 = tslib_1.__decorate(",
+                "    [module$contents$main_noopDecorator], module$contents$main_Foo);",
+                "if (false) {",
+                "  module$contents$main_Foo.ID;",
+                "  module$contents$main_Foo.ID2;",
+                "}",
+                "(new module$contents$main_Foo()).bar();")));
+  }
+
   @Test
   public void testDoNotCollapseDeletedProperty() {
     testSame(