Module B0_expect

Expectation tests.

Expectation tests run computations and write outputs on expectation files tracked by your VCS. The VCS can then be used to track and correct expectations.

See the TODO.


type t

The type for expectation contexts. An expectation context orchestrates and gathers the result of expectation tests.

val action_func : base:B0_std.Fpath.t -> (t -> unit) -> B0_action.func

action_func ~base f is an action function calling f ctx and handling test reporting and aborting. f should simply perform computations, add expectations to ctx and, possibly, aborting.

ctx checks expectations files stored in the base hierarchy. A relative base is made absolute with the scope directory of env.

A few things are setup via the command line arguments; run the cmdlet with --help to find out the details.


Warning. These functions may raise Abort.

val file : ?diff:bool -> t -> B0_std.Fpath.t -> unit

file ctx file adds file to the checked expectations files of ctx. A relative file is made absolute with base.

If diff is true (default) a diff is shown on a new or unexpected file whenever log_diffs is true. If false no diff is ever shown for file.

Raises Invalid_argument if file was already added to ctx.

val stdout : ?diff:bool -> t -> ?env:B0_std.Os.Env.assignments -> ?cwd:B0_std.Fpath.t -> ?stdout:B0_std.Fpath.t -> B0_std.Cmd.t -> unit

stdout ctx cmd synchronously runs cmd with and standard output redirected stdout and adds stdout to the checked expectations files of ctx. A relative stdout is made absolute with base.

stdout defaults to tool.stdout with tool the basename of cmd's tool. If you run the same program more than once you have to devise different names for each run.

For diff see corresponding argument of file.


This can be used to abort test runs when unexpected and non-recoverable errors are hit.

exception Abort of string

The exception for non recoverable errors. May be raised by any function acting on contexts of this module.

val abort : string -> 'a

error msg is raise (Error string).

val abortf : ('a, Stdlib.Format.formatter, unit, 'b) Stdlib.format4 -> 'a

abortf fmt … raises Abort with a message formatted according to fmt.

val result_to_abort : ('a, string) Stdlib.result -> 'a

result_to_abort r raises Abort if r is Error e and returns v if r is Ok v.

val abort_to_result : (unit -> 'a) -> ('a, string) Stdlib.result

abort_to_result f calls f () and catches Abort to turn them into an Error _ result.

Low-level interface


module Outcome : sig ... end

Expectation outcomes.

val make : ?vcs_repo:B0_vcs_repo.t -> ?log_absolute:bool -> ?log_diffs:bool -> B0_env.t -> base:B0_std.Fpath.t -> t

make env ~base is a test context in environment env with:

  • base is the directory in which expectations are stored. Relative expectation files are intepreted relative to base. A relative base is relative to the scope directory of env. Important. base should be a directory dedicated to expectations so that users can get easily get summaries and diffs via their VCS without the noise of surrounding changes.
  • log_diff, if true (default) logs diffs on unexpected and new outcomes.
  • log_absolute, if false (default) paths are logged relative to the cwd of env. If true all paths are made absolute.
  • repo is the VCS repository to use. By default looked up with B0_vcs_repo.find in B0_env.scope_dir.

Raises Abort if VCS detection fails.

val base : t -> B0_std.Fpath.t

base ctx is the absolute base path of ctx. A relative expectation file is made absolute with this value.

val base_files : ?rel:bool -> t -> recurse:bool -> B0_std.Fpath.t list

base_files ctx ~recurse are the absolute or relative (if rel is true, defaults to false) file paths in base ctx and sub directories if recurse is true.

val dur : t -> B0_std.Mtime.Span.t

dur ctx is the monotonic duration since ctx was created.

val env : t -> B0_env.t

env ctx is the environment of ctx.

val get_unit_exe_file_cmd : t -> B0_unit.t -> B0_std.Cmd.t

get_unit_exe ctx u is the executable of unit u. Raises Abort in case of error.

val log_absolute : t -> bool

log_absolute ctx is true if absolute paths are logged. If false path are made relative with the cwd of env.

val log_diffs : t -> bool

log_diffs ctx is true if unexpected and new outcomes log diffs.

val vcs_repo : t -> B0_vcs_repo.t

vcs ctx is the VCS used for operating the expectation files.

val outcomes : t -> Outcome.t list

outcomes ctx are the outcomes added with add_outcome to ctx, in reverse order of addition.


val outcome_of_file : ?diff:bool -> t -> B0_std.Fpath.t -> Outcome.t

outcome_of_file ?diff ctx file tests the expectation of file file in context ctx. A relative file is made absolute with base. diff indicates whether the diff of unexpected or new outcomes should be shown for file (defaults to true).

val add_outcome : t -> Outcome.t -> unit

add_outcome ctx o adds and logs outcome o in ctx.

val finish : t -> B0_std.Os.Exit.t

finish ctx logs a summary of expectations and returns 0 if everything was expected or 1 otherwise.