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yesodweb / yesod

A RESTful Haskell web framework built on WAI.
http://www.yesodweb.com/
MIT License
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Moving between `yesod devel` and running tests causing unnecessary rebuild #1661

Open danbroooks opened 4 years ago

danbroooks commented 4 years ago

When developing my application, I am using the yesod devel command for incremental re-compilation, and I also have a set of tests that i run using stack build --fast --flag myapp:library-only --flag myapp:dev --test --no-run-tests. If I build the tests first, in the output I get:

myapp> configure (lib + exe + test)

Then when I run yesod devel once the test have built I do not need to do a complete re-build to start the app, the inverse however isn't true. When I run yesod devel from scratch, the build output says:

myapp> configure (lib + exe)

Once I have done a full build, and I abort the command and run my test command, I get:

myapp> configure (lib + exe + test)

Again, and a full rebuild is required. Is there something I can do so that yesod devel includes building the tests as well? The raw command that devel generates here:

https://github.com/yesodweb/yesod/blob/master/yesod-bin/Devel.hs#L354

Works with that part omitted, but presumably this line cannot be simply dropped. Would a PR be acceptable against the devel command that supports omitting this part of the command with a flag or something?

Or is there something I am doing wrong here in terms of the commands I'm running?

snoyberg commented 4 years ago

One approach would be to use separate work directories for devel and testing. Can you try adding STACK_WORK=.stack-work-devel or similar in front of your yesod devel command and see if that fixes things for you? If it does, we may want to consider adding something like that to yesod devel out of the box.

danbroooks commented 4 years ago

Yeah that seems to have worked, obviously it is now running two separate stack-work directories though.

Though this seems to rectify the problem, it seems like a bit of a 'hammer to crack a nut' kind of solution, and perhaps not something to be fixed in this project, but infact potentially an issue with stack/cabal?

I have been hacking around with stack to try and pinpoint the issue, it seems like now my builds don't even behave how i want them to after a build with (lib + exe + test), I was getting a situation today where I would do a full build with stack printing out (lib + exe + test), then when i made a change in lib it would re-build the whole thing, printing out (lib), as opposed to with the approach you have suggested, where it incrementally builds as you would want it to...

Do you think this is something I should move to the issues for stack ?

If I build with tests like so: 

stack build --fast --test --flag myapp:library-only --flag myapp:dev

-- outputs:
myapp> build (lib + exe + test)

And then run this command (which is the raw command from yesod devel, minus the --exec "/home/dan/.local/bin/yesod devel-signal" flag):

stack build --fast --file-watch myapp:lib --flag myapp:dev --flag myapp:library-only

I get this output:

Success! Waiting for next file change.
Type help for available commands. Press enter to force a rebuild.

Then when I make a file change, this results in the whole lib project needing to be rebuilt, and the following output:

myapp> build (lib)