Fix indentation in generated browser code

[wang-li]

Overview

In this PR, I fixed the indentations in ShowkaseBrowserWriter so that it does not shift the code by a double indentation every time it generates code for a preview parameter provider.

The results were asserted by looking at the generated files (the fixed indent is at line 101 in the following screenshots):

Before	After

I also added the extension withDoubleIndent { } so that the indentations can safely unindent after the relevant block. This extension is based on the existing withIndent { } extension from Kotlin poet.

Finally, I wanted to add a unit test to avoid this issue to resurface but I struggled to understand how the unit tests in showkase-processor-testing work... But I'm open for some guidance! 😄

This fixes #257

[vinaygaba]

@wang-li Thank you for contributing and fixing this issue 🙏🏻

For the ShowkaseProcessor tests, here's what you will need to do:

1. Add a new test to this file
2. Create a folder with the same name as the test that you added in (1) and create the test Composable files in a folder called input. You will add that here - https://github.com/airbnb/Showkase/tree/master/showkase-processor-testing/src/test/resources/ShowkaseProcessorTest
3. You can auto generated the output by setting this boolean to true and running the tests locally once - https://github.com/airbnb/Showkase/blob/master/showkase-processor-testing/src/test/java/com/airbnb/android/showkase_processor_testing/BaseProcessorTest.kt#L18
4. Commit this test folder along with the input and output subfolders.

[wang-li]

Thank you very much for the instructions @vinaygaba! 🙏
I updated the commit, adding the relevant test and removing the previous unit tests changes in the showkase-browser-testing to reduce the noise around this PR 😉

[vinaygaba]

@wang-li Can you rename this test to the following since it describes it better. You will also need to rename the corresponding folder.

composable previews with multiple parameter providers should indent properly

[wang-li]

@vinaygaba For sure 👍 It's done in an additional commit 😉

[vinaygaba]

One final change needed but great job in fixing this. Thank you 🥳

[wang-li]

Thank you for taking the time to review my PR 🙏

[wang-li]

Hey @vinaygaba 👋 Would it be possible to get a new release in order to benefit this fix through a gradle dependency? 🙏

[vinaygaba]

@wang-li I was hoping to get one more change in before I do the next release. You can expect it tomorrow

[hhalse]

Hey @vinaygaba 👋 Will there be a new release for this fix?