ppx_inline_test =============== Syntax extension for writing in-line tests in ocaml code. New syntactic constructs ------------------------ The following constructs are now valid structure items: ```ocaml let%test "name" = (* true means ok, false or exn means broken *) let%test_unit "name" = (* () means ok, exn means broken *) let%test_module "name" = (module ) (* to group tests (to share some setup for instance) *) ``` We may write `_` instead of `"name"` for anonymous tests. When running tests, they will be executed when the control flow reaches the structure item (i.e. at toplevel for a toplevel test; when the functor is applied for a test defined in the body of a functor, etc.). Tags ---- One can tag tests with the following construct: ```ocaml let%test "name" [@tags "no-js"] = let%test "name" [@tags "no-js", "other-tag"] = let%test _ [@tags "no-js"] = let%test _ [@tags "js-only"] = ``` Available tags are: * `no-js` for tests that should not run when compiling Ocaml to Javascript * `js-only` for tests that should only run in Javascript * `32-bits-only` for tests that should only run in 32 bits architectures * `64-bits-only` for tests that should only run in 64 bits architectures * `x-library-inlining-sensitive` for tests that might only pass when compiling with cross library inlining switched on One can also tag entire test modules similarly: ```ocaml let%test_module "name" [@tags "no-js"] = (module struct end) ``` The flags `-drop-tag` and `-require-tag` can be passed to the test runner to restrict which tests are run. We say the tags of a test are the union of the tags applied directly to that test using `[@tags ...]` and the tags of all enclosing modules. It is to this union that the predicates `-drop-tag` and `-require-tag` are applied. If it is clear, from a test-module's tags, that none of the tests within will possibly match the tag predicates imposed by the command line flags, then additionally the top-level of that module will not be run. Examples -------- ### prime.ml ```ocaml let is_prime = let%test _ = is_prime 5 let%test _ = is_prime 7 let%test _ = not (is_prime 1) let%test _ = not (is_prime 8) ``` ### Tests in a functor. ```ocaml module Make(C : S) = struct let%test _ = end module M = Make(Int) ``` ### Grouping test and side-effecting initialisation. Since the module passed as an argument to `let%test_module` is only initialised when we run the tests, it is ok to perform side-effects in the module-expression argument. ```ocaml let%test_module _ = (module struct module UID = Unique_id.Int(struct end) let%test _ = UID.create() <> UID.create() end) ``` Building and running the tests at jane street -------------------------------- Inline tests can only be used in libraries, not executables. The standard build rules create an executable script `inline_tests_runner` which runs all tests in the directory. This script takes optional arguments (see below) to restrict which tests are run. The full set of tests are run when building the jenga `runtest` alias. jenga .runtest Building and running the tests outside of jane street ---------------------------------------- Code using this extension must be compiled and linked using the `ppx_inline_test.runtime.lib` library. The `ppx_inline_test` syntax extension will reject any test if it wasn't passed a `-inline-test-lib libname` flag. To integrate this in your build system, you should look at the instruction provided for [the ppx\_driver ocamlbuild plugin](https://github.com/janestreet/ppx_driver). There are a few working example using oasis in the [Jane Street tests](https://github.com/janestreet/jane-street-tests). ### Execution Tests are executed when the executable containing the tests is called with command line arguments: your.exe inline-test-runner libname [options] otherwise they are ignored. This `libname` is a way of restricting the tests run by the executable. The dependencies of your library (or executable) could also use `ppx_inline_test`, but you don't necessarily want to run their tests too. For instance, `core` is built by giving `-inline-test-lib core` and `core_extended` is built by giving `-inline-test-lib core_extended`. And now when an executable linked with both `core` and `core_extended` is run with a `libname` of `core_extended`, only the tests of `core_extended` are run. Finally, after running tests, `Ppx_inline_test_lib.Runtime.exit ()` should be called (to exit with an error and a summary of the number of failed tests if there were errors or exit normally otherwise). Command line arguments ---------------------- The executable that runs tests can take additional command line arguments. The most useful of these are: * `-verbose` to see the tests as they run * `-only-test location` where location is either a filename `-only-test main.ml`, a filename with a line number `-only-test main.ml:32`, or with the syntax that the compiler uses: `File "main.ml"`, or `File "main.ml", line 32` or `File "main.ml", line 32, characters 2-6` (characters are ignored). The position that matters is the position of the `let%test` or `let%test_unit`. The positions shown by `-verbose` are valid inputs for `-only-test`. If no `-only-test` flag is given, all the tests are run. Otherwise all the tests matching any of the locations are run. * `-drop-tag tag` drop all the tests tagged with `tag`. Parallelizing tests ------------------- If you pass arguments of the form `-inline-test-lib lib:partition` to `ppx_inline_test`, then you will be able to run tests from a given source file in parallel with tests from other source files. All the tests inside the same source file are still run sequentially. You should pick different `partition` names for the different files in your library (the name of the .ml files for instance). `ppx_inline_test_lib` currently requires some external system like a build system to run it multiple times in parallel, although we may make it possible to run the inline tests in parallel directly in the future. If you do that, you can now use two new flags of the executable containing the tests: * `-list-partitions` lists all the partitions that contain at least one test, one per line. * `-partition P` only run the tests of the library that are encountered at toplevel of the source file that was preprocessed with the given partition `P` (the tests need not be syntactically in the file, they could be the result of applying a functor) A build system can combine these two commands by first listing partitions, and then running one command for each partition.