sql: delete TestSchemaChangeCompletion

Informs: cockroachdb#51796

The test is very buggy and not doing what it was supposed to test.
Deleting since we already have TestLegacySchemaChangerWaitsForOtherSchemaChanges
and TestConcurrentSchemaChangesDoNotDeadlock.

Release note: None

Author: chengxiong-ruan

pkg/sql/schema_changer_test.go

@@ -4170,94 +4170,6 @@ CREATE TABLE t.test (k INT PRIMARY KEY, v INT);
 	}
 }
 
-// Tests that a schema change that is queued behind another schema change
-// is executed through the synchronous execution path properly even if it
-// gets to run before the first schema change.
-func TestSchemaChangeCompletion(t *testing.T) {
-	defer leaktest.AfterTest(t)()
-	defer log.Scope(t).Close(t)
-	skip.WithIssue(t, 51796)
-	// TODO (lucy): This test needs more complicated schema changer knobs than is
-	// currently implemented.
-	params, _ := tests.CreateTestServerParams()
-	var notifySchemaChange chan struct{}
-	var restartSchemaChange chan struct{}
-	params.Knobs = base.TestingKnobs{
-		SQLSchemaChanger: &sql.SchemaChangerTestingKnobs{},
-	}
-	s, sqlDB, kvDB := serverutils.StartServer(t, params)
-	ctx := context.Background()
-	defer s.Stopper().Stop(ctx)
-	codec := s.ApplicationLayer().Codec()
-
-	if _, err := sqlDB.Exec(`
-CREATE DATABASE t;
-CREATE TABLE t.test (k INT PRIMARY KEY, v INT);
-`); err != nil {
-		t.Fatal(err)
-	}
-
-	// Add some data
-	const maxValue = 200
-	if err := sqltestutils.BulkInsertIntoTable(sqlDB, maxValue); err != nil {
-		t.Fatal(err)
-	}
-	if err := sqltestutils.CheckTableKeyCount(ctx, kvDB, codec, 1, maxValue); err != nil {
-		t.Fatal(err)
-	}
-	if err := sqlutils.RunScrub(sqlDB, "t", "test"); err != nil {
-		t.Fatal(err)
-	}
-
-	// Do not execute the first schema change so that the second schema
-	// change gets queued up behind it. The second schema change will be
-	// given the green signal to execute before the first one.
-	var wg sync.WaitGroup
-	wg.Add(2)
-	notifySchemaChange = make(chan struct{})
-	restartSchemaChange = make(chan struct{})
-	restart := restartSchemaChange
-	go func() {
-		if _, err := sqlDB.Exec(`CREATE UNIQUE INDEX foo ON t.test (v)`); err != nil {
-			t.Error(err)
-		}
-		wg.Done()
-	}()
-
-	<-notifySchemaChange
-
-	notifySchemaChange = make(chan struct{})
-	restartSchemaChange = make(chan struct{})
-	go func() {
-		if _, err := sqlDB.Exec(`CREATE UNIQUE INDEX bar ON t.test (v)`); err != nil {
-			t.Error(err)
-		}
-		wg.Done()
-	}()
-
-	<-notifySchemaChange
-	// Allow second schema change to execute.
-	close(restartSchemaChange)
-
-	// Allow first schema change to execute after a bit.
-	time.Sleep(time.Millisecond)
-	close(restart)
-
-	// Check that both schema changes have completed.
-	wg.Wait()
-	if err := sqltestutils.CheckTableKeyCount(ctx, kvDB, codec, 3, maxValue); err != nil {
-		t.Fatal(err)
-	}
-
-	// The notify schema change channel must be nil-ed out, or else
-	// running scrub will cause it to trigger again on an already closed
-	// channel when we run another statement.
-	notifySchemaChange = nil
-	if err := sqlutils.RunScrub(sqlDB, "t", "test"); err != nil {
-		t.Fatal(err)
-	}
-}
-
 // Test that a table TRUNCATE leaves the database in the correct state
 // for the asynchronous schema changer to eventually execute it.
 func TestTruncateInternals(t *testing.T) {