| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
Test.Tasty.Golden
Description
Getting Started
To get started with golden testing and this library, see Introduction to golden testing.
This module provides a simplified interface. If you want more, see Test.Tasty.Golden.Advanced.
Filenames
Filenames are looked up in the usual way, Thus relative
names are relative to the processes current working directory.
It is common to run tests from the package's root directory (via cabal
test or cabal install --enable-tests), so if your test files are under
the tests/ subdirectory, your relative file names should start with
tests/ (even if your test.hs is itself under tests/, too).
Line endings
The best way to avoid headaches with line endings (when running tests both on UNIX and Windows) is to treat your golden files as binary, even when they are actually textual.
This means:
- When writing output files from Haskell code, open them in binary mode
(see
openBinaryFile,withBinaryFileandhSetBinaryMode). This will disable automatic\n -> \r\nconversion on Windows. For convenience, this module exportswriteBinaryFilewhich is just likewriteFilebut opens the file in binary mode. When usingByteStrings note that Data.ByteString and Data.ByteString.Lazy use binary mode forwriteFile, while Data.ByteString.Char8 and Data.ByteString.Lazy.Char8 use text mode. - Tell your VCS not to do any newline conversion for golden files. For
git check in a
.gitattributesfile with the following contents (assuming your golden files have.goldenextension):
*.golden -text
On its side, tasty-golden reads and writes files in binary mode, too.
Why not let Haskell/git do automatic conversion on Windows? Well, for
instance, tar will not do the conversion for you when unpacking a release
tarball, so when you run cabal install your-package --enable-tests, the
tests will be broken.
As a last resort, you can strip all \rs from both arguments in your
comparison function when necessary. But most of the time treating the files
as binary does the job.
Linking
The test suite should be compiled with -threaded if you want to avoid
blocking any other threads while goldenVsFileDiff and similar functions
wait for the result of the diff command.
Windows limitations
When using goldenVsFileDiff or goldenVsStringDiff under Windows the exit
code from the diff program that you specify will not be captured correctly
if that program uses exec.
More specifically, you will get the exit code of the original child
(which always exits with code 0, since it called exec), not the exit
code of the process which carried on with execution after exec.
This is different from the behavior prescribed by POSIX but is the best
approximation that can be realised under the restrictions of the
Windows process model. See Process for further details or
https://github.com/haskell/process/pull/168 for even more.
Synopsis
- goldenVsFile :: TestName -> FilePath -> FilePath -> IO () -> TestTree
- goldenVsString :: TestName -> FilePath -> IO ByteString -> TestTree
- goldenVsFileDiff :: TestName -> (FilePath -> FilePath -> [String]) -> FilePath -> FilePath -> IO () -> TestTree
- goldenVsStringDiff :: TestName -> (FilePath -> FilePath -> [String]) -> FilePath -> IO ByteString -> TestTree
- newtype SizeCutoff = SizeCutoff {}
- data DeleteOutputFile
- writeBinaryFile :: FilePath -> String -> IO ()
- findByExtension :: [FilePath] -> FilePath -> IO [FilePath]
- createDirectoriesAndWriteFile :: FilePath -> ByteString -> IO ()
Functions to create a golden test
Arguments
| :: TestName | test name |
| -> FilePath | path to the «golden» file (the file that contains correct output) |
| -> FilePath | path to the output file |
| -> IO () | action that creates the output file |
| -> TestTree | the test verifies that the output file contents is the same as the golden file contents |
Compare the output file's contents against the golden file's contents after the given action has created the output file.
Arguments
| :: TestName | test name |
| -> FilePath | path to the «golden» file (the file that contains correct output) |
| -> IO ByteString | action that returns a string |
| -> TestTree | the test verifies that the returned string is the same as the golden file contents |
Compare a given string against the golden file's contents.
Arguments
| :: TestName | test name |
| -> (FilePath -> FilePath -> [String]) | function that constructs the command line to invoke the diff command. E.g. \ref new -> ["diff", "-u", ref, new] |
| -> FilePath | path to the golden file |
| -> FilePath | path to the output file |
| -> IO () | action that produces the output file |
| -> TestTree |
Same as goldenVsFile, but invokes an external diff command.
See the notes at the top of this module regarding linking with
-threaded and Windows-specific issues.
Arguments
| :: TestName | test name |
| -> (FilePath -> FilePath -> [String]) | function that constructs the command line to invoke the diff command. E.g. \ref new -> ["diff", "-u", ref, new] |
| -> FilePath | path to the golden file |
| -> IO ByteString | action that returns a string |
| -> TestTree |
Same as goldenVsString, but invokes an external diff command.
See the notes at the top of this module regarding linking with
-threaded and Windows-specific issues.
Options
newtype SizeCutoff Source #
The size, in bytes, such that the (incorrect) test output is not displayed when it exceeds this size. Numeric underscores are accepted for readability.
The default value is 1000 (i.e. 1Kb).
Since: 2.3.3
Constructors
| SizeCutoff | |
Fields | |
Instances
data DeleteOutputFile Source #
When / whether to delete the test output file, when there is a golden file
Since: 2.3.4
Constructors
| Never | Never delete the output file (default) |
| OnPass | Delete the output file if the test passes |
| Always | Always delete the output file. (May not be commonly used, but provided for completeness.) |
Instances
Various utilities
Find all files in the given directory and its subdirectories that have the given extensions.
It is typically used to find all test files and produce a golden test per test file.
The returned paths use forward slashes to separate path components, even on Windows. Thus if the file name ends up in a golden file, it will not differ when run on another platform.
The semantics of extensions is the same as in takeExtension. In
particular, non-empty extensions should have the form ".ext".
This function may throw any exception that getDirectoryContents may
throw.
It doesn't do anything special to handle symlinks (in particular, it probably won't work on symlink loops).
Nor is it optimized to work with huge directory trees (you'd probably want to use some form of coroutines for that).
createDirectoriesAndWriteFile :: FilePath -> ByteString -> IO () Source #
Like writeFile, but also create parent directories if they are
missing.