Fix no table is replicated when excludeTableRegex is set while includeTableRegex is nil

[gaojijun]

fix #873

[lance6716]

Thanks, please fix the lint error

  canal/canal.go:299: File is not `goimports`-ed (goimports)

And can you update the canal_test.go like TestCanalFilter to add an unit test for it?

[gaojijun]

Thanks, please fix the lint error

  canal/canal.go:299: File is not `goimports`-ed (goimports)

And can you update the canal_test.go like TestCanalFilter to add an unit test for it?

Done

[lance6716]

Hi, I mean add a test to explain your change. I manually deleted line 302~303 and the test TestIncludeExcludeTableRegex can still pass. I want a failed test without the change as issue said

[gaojijun]

Hi, I mean add a test to explain your change. I manually deleted line 302~303 and the test TestIncludeExcludeTableRegex can still pass. I want a failed test without the change as issue said

Sorry, my fault. It's updated, please take a look.

[lance6716]

Can you also update the comment of IncludeTableRegex and ExcludeTableRegex to explain the behaviout when either is not set?

My last concern is by Hyrum's Law we should not change the behaviour of API, but I think this change does no harm. Because the old behaviour will replicate nothing so there should be no user using it. As a user, I directly use BinlogSyncer and don't use canal package, @froot can you give your opinion?

rest lgtm

[gaojijun]

// Default IncludeTableRegex and ExcludeTableRegex are empty, this will include all tables

@lance6716 Is this comment good enough? It's already in the code.

[lance6716]

// Default IncludeTableRegex and ExcludeTableRegex are empty, this will include all tables

@lance6716 Is this comment good enough? It's already in the code.

It means both are empty, not one of them is empty

[gaojijun]

// Default IncludeTableRegex and ExcludeTableRegex are empty, this will include all tables
@lance6716 Is this comment good enough? It's already in the code.

It means both are empty, not one of them is empty

updated