I’m writing an integration test for a Gradle plugi...

# getting-started

[Adam S]

I’m writing an integration test for a Gradle plugin that generates a HTML site. I’ve got the expected file structure, and I need to compare it against the actual generated site.

I think it would be nice to generate a pretty file tree

`
└── site/
    ├── styles/
    │   └── site.css
    ├── images/
    │   └── icon.png
    └── index.html

the expected/actual so the test assertion is just a simple string-comparison check, and I like that it would give a clear test-failure

How can I generate such a pretty tree in Kotlin/JVM? Or maybe there’s a test assertion library that can help?

[Adam S]

it was less difficult than I thought to come up with something workable!

import java.io.File

fun File.toPrettyTreeString(): String {
  return walk().joinToString("\n") { file ->
    val relativeFile = file.relativeTo(this)
    val depth = relativeFile.invariantSeparatorsPath.count { it == '/' }

    file.name.prependIndent(" ".repeat(depth))
  }
}

generates:

html
    index.html
    -basic -project
     it.protected
      index.html
      -protected-class
       index.html
       protected-fun.html
       -protected-class.html

Next step is to try and compare file contents….

[Damien O'Hara]

I had to do a similar thing recently. here is my drawFileTree code if it helps: https://github.com/mfwgenerics/markout/blob/7a1b81e3a6c773b67fa42e3977599b3285a5e930/readme/src/main/kotlin/Util.kt#L58-L104

[Damien O'Hara]

just cleaned it up and made it self-contained.

gist: https://gist.github.com/mfwgenerics/d1ec89eb80c95da9d542a03b49b5e15b
playground link: https://pl.kotl.in/W9vDI9E-x

output:

`
└── site
    ├── styles
    │   └── site.css
    ├── images
    │   └── icon.png
    └── index.html

hope it helps!

[Adam S]

thanks, that’s half of the problem. I like the output, it’s pretty with the proper ascii pipe

The first part is how to convert a java.io.File to a Node…

In the end I found out that Kotest has a util for comparing file structures and content, so I just used that

https://github.com/kotest/kotest/blob/ed015bd0e061dc1854f7e0702038b569b7e0a766/kotest-assertions/kotest-assertions-core/src/jvmMain/kotlin/io/kotest/matchers/file/matchers.kt#L250

https://github.com/kotest/kotest/blob/ed015bd0e061dc1854f7e0702038b569b7e0a766/kotest-assertions/kotest-assertions-core/src/jvmMain/kotlin/io/kotest/matchers/file/matchers.kt#L289

[Damien O'Hara]

I would also lean towards kotest for this. for posterity I have updated the file tree gist to work with java.nio.file.Path (obtainable by calling File.toPath)

[Adam S]

😬 StackOverflowError

Untitled.txt

[Adam S]

I did have to change

val entries = dir.listDirectoryEntries()

to

val entries = dir.toFile().walk().maxDepth(1).toList()

since Gradle 7.6 limits Kotlin to 1.4

[Adam S]

ah, this is the fix

val entries = dir.toFile().walk().maxDepth(1).filter { it != dir.toFile() }

[Adam S]

I refactored it :)

fileTree_kt.kt

[Adam S]

the result is exactly what I’m looking for

thanks very much for your help!

Untitled.txt

[Damien O'Hara]

Glad it helped 👏. That refactor looks great!