update splitDirectories function

[d12frosted]

I propose this solution for issue #3.

In short, currently concat . splitDirectories /= id.

Here is example of using concat . splitDirectories:

> Filesystem.Path.concat $ splitDirectories "/path/to/file"
FilePath "//path/to/file"

In my commit I updated splitDirectories function, so now it treats root part as pathRoot, but not as pathBasename.

I have run all testes, and here is content of log file:

Test suite filesystem_path_tests: RUNNING...
PASS: 47 tests run, 47 tests passed
Test suite filesystem_path_tests: PASS
Test suite logged to: dist/test/system-filepath-0.4.13.1-filesystem_path_tests.log

I found that there is test_SplitDirectories function in FilesystemPathTests.hs file:

test_SplitDirectories :: Test
test_SplitDirectories = assertions "splitDirectories" $ do
    let splitDirectories x = map toChar8 (P.splitDirectories (fromChar8 x))

    $expect $ equal (splitDirectories "") []
    $expect $ equal (splitDirectories "/") ["/"]
    $expect $ equal (splitDirectories "/a") ["/", "a"]
    $expect $ equal (splitDirectories "/ab/cd") ["/", "ab", "cd"]
    $expect $ equal (splitDirectories "/ab/cd/") ["/", "ab", "cd"]
    $expect $ equal (splitDirectories "ab/cd") ["ab", "cd"]
    $expect $ equal (splitDirectories "ab/cd/") ["ab", "cd"]
    $expect $ equal (splitDirectories "ab/cd.txt") ["ab", "cd.txt"]
    $expect $ equal (splitDirectories "ab/cd/.txt") ["ab", "cd", ".txt"]
    $expect $ equal (splitDirectories "ab/./cd") ["ab", ".", "cd"]

So probably it couldn't find the problem because of toChar8 . f . fromChar8. Basically, that's what I get if I don't convert toChar8:

> splitDirectories (fromChar8 "/")  == [fromChar8 "/"]
False
> Prelude.map toChar8 (splitDirectories (fromChar8 "/"))  == Prelude.map toChar8 [fromChar8 "/"]
True

Also I see that there are other places where toChar8 . f . fromChar8 conversion is used, so I am going to check those functions as well.

Sorry for long message.
Cheers and thanks for your awesome library!

[d12frosted]

I checked the test function. And here are my thought about how to update it.

My first attempt was to compare lists of FilePaths:

test_SplitDirectories :: Test
test_SplitDirectories = assertions "splitDirectories" $ do
        let splitDirectories x = P.splitDirectories (fromChar8 x)
            fromChar8' = map fromChar8

        $expect $ equal (splitDirectories "") (fromChar8' [""])
        $expect $ equal (splitDirectories "/") (fromChar8' ["/"])
        $expect $ equal (splitDirectories "/a") (fromChar8' ["/", "a"])
        $expect $ equal (splitDirectories "/ab/cd") (fromChar8' ["/", "ab", "cd"])
        $expect $ equal (splitDirectories "/ab/cd/") (fromChar8' ["/", "ab", "cd"])
        $expect $ equal (splitDirectories "ab/cd") (fromChar8' ["ab", "cd"])
        $expect $ equal (splitDirectories "ab/cd/") (fromChar8' ["ab", "cd"])
        $expect $ equal (splitDirectories "ab/cd.txt") (fromChar8' ["ab", "cd.txt"])
        $expect $ equal (splitDirectories "ab/cd/.txt") (fromChar8' ["ab", "cd", ".txt"])
        $expect $ equal (splitDirectories "ab/./cd") (fromChar8' ["ab", ".", "cd"])

But cabal test showed me

equal: [FilePath "ab",FilePath ".",FilePath "cd"] is not equal to [FilePath "ab",FilePath "./",FilePath "cd"]

So yeah. that's was expectable. The second attempt was to use concat . splitDirectories:

test_SplitDirectories :: Test
test_SplitDirectories = assertions "splitDirectories" $ do
    let splitDirectories x = P.concat $ P.splitDirectories (fromChar8 x)

    $expect $ equal (splitDirectories "") (fromChar8 "")
    $expect $ equal (splitDirectories "/") (fromChar8 "/")
    $expect $ equal (splitDirectories "/a") (fromChar8 "/a")
    $expect $ equal (splitDirectories "/ab/cd") (fromChar8 "/ab/cd")
    $expect $ equal (splitDirectories "/ab/cd/") (fromChar8 "/ab/cd")
    $expect $ equal (splitDirectories "ab/cd") (fromChar8 "ab/cd")
    $expect $ equal (splitDirectories "ab/cd/") (fromChar8 "ab/cd")
    $expect $ equal (splitDirectories "ab/cd.txt") (fromChar8 "ab/cd.txt")
    $expect $ equal (splitDirectories "ab/cd/.txt") (fromChar8 "ab/cd/.txt")
    $expect $ equal (splitDirectories "ab/./cd") (fromChar8 "ab/./cd")

(yeah, probably I should use another name instead of splitDirectories)

All tests are passed and I am happy.

But wait. While I do like using concat . splitDirectories == id property I am concerned about previous equality failure.

My intuition says me that splitDirectories "ab/./cd" should be equal to fromChar8' ["ab", ".", "cd"].

Current definition of splitDirectories function treats all dirs as basenames. And that's probably not what we want.

Checkout my last commit to see what I've got.

[d12frosted]

Hm, just checked cabal test for few times and found:

[ FAIL  ] tests.validity.windows
  note: seed=4823750214036955069

    *** Failed! Falsifiable (after 30 tests): 
FilePath "c\FS2H/\ENQ\DELQ\SI\135/\223RO&\244\131\151:&/t%f/Lt\167\194\176\199\GSL `/c/{\SO/`M/\a/\172\241^:/>~\172`d8T\252/{/\166c\DLE\142\rN>!/<\176\fy_\134K\a\DLE\US/0Bv%u \EMD/L\ESCc\DC1^/\237Ra\233\FS/b\206y</!/J/\249nT\195/\DEL/>P*\SI\171V9/>j'Fy;\FS/\165\&4\DLE\157q}pi5/B\209h<\201g(2'/Q\163\t<X/*\242\143Y\SOH\230P/|/\148\GS~Y/\136r\166\142"

But I saw it only once.

[snoyberg]

@chrisdone Can you look into this?

[d12frosted]

Ping. Any updates on this?

[chrisdone]

Checking it out.

[chrisdone]

So there's quite a mess of invariants flying around in this library. But the ./ stuff is already a problem, seemingly regardless of this patch.

Where are your fromChar8/toChar8 coming from?

[chrisdone]

Ah, from the test suite.

[chrisdone]

Okay, this gives at least the property of identity on concat . splitDirectories. Okay to merge from my side.

Passing to @snoyberg.

[d12frosted]

@chrisdone thanks for checking my commit

But the ./ stuff is already a problem, seemingly regardless of this patch.

True indeed.