Metadata

This feature is available as of Midje 1.5-alpha2.

Short version

In your source:

(fact :slow ...) ; Runs slowly
(fact "a core fact" :core)
(fact "metadata map" {:priority 5})

In the repl:

(load-facts :core)    ; Load-and-check only the core facts

(load-facts :all)                ; ":all" is not a metadata key. Loads all namespaces.
(check-facts :core)              ; Check a subset
(check-facts (complement :core)  ; Check the other facts.

With lein repl:

% lein midje :filter core -slow ; select tests that are "core" or not "slow"

Details

Defining metadata

There are two ways to define metadata:

;; A map can be given:
(fact "My favorite fact"
  {:group core, :speed slow} 
  ...)

;; Isolated keywords are taken to be metadata keys whose value is `true`:
(fact :integration ...)

Note that metadata is auto-quoted. In the first fact above, the metadata didn't need to be quoted. The same is true of symbols that name facts.

Fact nesting

With the exception of the :midje/description (which is used to compose failure messages), metadata in interior facts is ignored. You cannot, for example, choose to run only one sub-fact of an outer fact.

You might want a number of tests that are all integration tests. You might not want to put :integration metadata on each one. You can avoid that in two ways. First, you could wrap all the facts in an outermost fact:

(fact :integration
  (fact ...)
  (fact ...)
  ...)

That's a good solution if you only ever want to check all the integration facts together. It's not if you want to check individual facts. In such cases, use fact-group:

(fact-group :integration
  (fact ...)
  (fact {:speed :slow} ...)
)

The fact-group metadata is merged with the individual facts' metadata.

Tabular facts

Tabular facts can take metadata. It can be placed either after the tabular token or the enclosed fact token. That is, the following two constructs mean the same thing:

(tabular "arithmetic" :foundation
  (fact 
     (+ ?a ?b) => ?c)
     ?a     ?b    ?c
     1      2     3
     2      2     4)

(tabular 
  (fact "arithmetic" :foundation
     (+ ?a ?b) => ?c)
     ?a     ?b    ?c
     1      2     3
     2      2     4)

Automatic metadata

All facts also get some predefined metadata:

:midje/description
The fact's outermost doc-string, if given. It is the description that is printed when a fact fails.

:midje/name
The name of the fact. If a symbol is given in the metadata position, the string name of that symbol becomes the name. Otherwise, if a doc string is given, it becomes the name. Otherwise, there is no name. (Names are relevant to redefining facts when reloading. See the compendium.

:midje/file, :midje/line, midje/namespace:
These identify the source of the fact. The line number is that of the beginning of the fact. The namespace is the symbol name of the enclosing namespace, not the namespace itself.

:midje/source: The original source of the fact.

Here are examples of :midje/description and :midje/name:

;; "doc string" is both the name and the description.
(fact "doc string" ...)

;; The string "cons" is the name. There is no description.
(fact cons ...)

;; The string "cons" is the name. "Cons tests" is the description.
(fact "Cons tests" cons 
  ...)