test: remove destructor from node_test_fixture

This commit removes the destructor from node_test_fixture.h which calls
the TearDown function causing TearDown to be called twice. This also
allows us to remove the check of the platform_ in TearDown.

Also the Setup/TearDown functions in AliasBufferTest are removed as they
are not necessary.

PR-URL: #18524
Reviewed-By: James M Snell <jasnell@gmail.com>

test/cctest/node_test_fixture.h

@@ -61,10 +61,6 @@ class NodeTestFixture : public ::testing::Test {
  protected:
   v8::Isolate* isolate_;
 
-  ~NodeTestFixture() {
-    TearDown();
-  }
-
   virtual void SetUp() {
     CHECK_EQ(0, uv_loop_init(&current_loop));
     platform_ = new node::NodePlatform(8, &current_loop, nullptr);
@@ -76,7 +72,6 @@ class NodeTestFixture : public ::testing::Test {
   }
 
   virtual void TearDown() {
-    if (platform_ == nullptr) return;
     platform_->Shutdown();
     while (uv_loop_alive(&current_loop)) {
       uv_run(&current_loop, UV_RUN_ONCE);

test/cctest/test_aliased_buffer.cc

@@ -5,16 +5,7 @@
 
 using node::AliasedBuffer;
 
-class AliasBufferTest : public NodeTestFixture {
- protected:
-  void SetUp() override {
-    NodeTestFixture::SetUp();
-  }
-
-  void TearDown() override {
-    NodeTestFixture::TearDown();
-  }
-};
+class AliasBufferTest : public NodeTestFixture {};
 
 template<class NativeT>
 void CreateOracleValues(NativeT* buf, size_t count) {