[Issue #82] a lot more syntax validations for formula

FORMULAS-BACKLOG-AND-FEATURE-IDEAS.md

@@ -12,9 +12,10 @@
 * [x] don't run more tests than need be if there is already failure in this formula's batch.
 
 * [x] syntax validate thata formula only has one check in it  
-  a. [ ] need to make this more thorough... right now the only test of this feature checks a 
+  a. [x] need to make this more thorough... right now the only test of this feature checks a 
      simple provided case, but needs to work with against-background, background and 
-     other more interesting cases  
+     other more interesting cases 
+  b. [ ] it is more thorough now, but let's make it *seriously* thoough :)
 
 * [x] formula macro calls a (constantly []) version of shrink on failures  
 

src/midje/ideas/formulas.clj

@@ -1,11 +1,11 @@
 (ns ^{:doc "Midje's special blend of generative-style testing."}
   midje.ideas.formulas
-  (:use [midje.util.form-utils :only [named? pop-docstring]]
+  (:use [midje.util.form-utils :only [first-named? named? pop-docstring]]
         [midje.error-handling.validation-errors :only [simple-report-validation-error 
                                                        validate when-valid]]
         [midje.ideas.prerequisites :only [is-head-of-form-providing-prerequisites?]]
-        [midje.ideas.arrows :only [leaves-contain-arrow? 
-                                   leaf-expect-arrows]]))
+        [midje.ideas.arrows :only [leaf-expect-arrows leaves-contain-arrow?]]
+        [clojure.walk :only [prewalk]]))
 
 (def ^{:doc "The number of facts generated per formula."
        :dynamic true} 
@@ -66,9 +66,12 @@
          (finally
            ~conclusion-signal)))))
 
-(defn- check-part-of [form] 
-  (take-while #(not (and (named? %) (#{"provided" "against-background"} (name %)))) 
-              (flatten form)))
+(defn- check-part-of [form]
+  (prewalk (fn [form] 
+             (if (some (partial first-named? form) ["against-background" "background" "provided"])
+                 '() 
+                 form)) 
+    form))
 
 (defmethod validate "formula" [[_formula_ & args :as form]]
   (cond (not (leaves-contain-arrow? (check-part-of args)))
@@ -82,6 +85,9 @@
               (odd? (count bindings))
               (< (count bindings) 2)))
         (simple-report-validation-error form "Formula requires bindings to be an even numbered vector of 2 or more:")
+
+        (some #(and (named? %) (= "background" (name %))) (flatten args))
+        (simple-report-validation-error form "background cannot be used inside of formula")
 
         :else 
         args))

test/midje/ideas/t_formulas.clj

@@ -13,31 +13,55 @@
   (formula [a 1])
   (formula [a 1] 1)
   (formula "vector fact" [a 1] (contains 3))
-  (formula "vector fact" [a 1] (contains 3))
 
-  (formula "vector fact" [a 1] 
+  (formula "ignores arrows in provideds" [a 1] 
     (contains 3)
     (provided (h anything) => 5))
 
-  (formula "vector fact" [a 1] 
+  (formula "ignores arrows in against-background" [a 1] 
     (contains 3)
     (against-background (h anything) => 5))
 
-;  (formula "vector fact" [a 1]
-;    (against-background (h anything) => 5)
-;    (contains 3))
-  )
+  (formula "ignores arrows in against-background - even when it comes first" 
+    [a 1]
+    (against-background (h anything) => 5)
+    (contains 3))
 
-(causes-validation-error #"There are too many expections in your formula form"
-  (formula "vector fact" [a 1] a => 1 a => 1))
+  (formula "ignores arrows in background" [a 1] 
+    (contains 3)
+    (background (h anything) => 5))
+
+  (formula "ignores arrows in background - even when it comes first" 
+    [a 1]
+    (background (h anything) => 5)
+    (contains 3)))
 
 (each-causes-validation-error #"Formula requires bindings to be an even numbered vector of 2 or more"
   (formula "vector fact" :not-vector 1 => 1)
   (formula "vector fact" [a 1 1] 1 => 1)
   (formula "vector fact" [] 1 => 1))
 
+(causes-validation-error #"There are too many expections in your formula form"
+  (formula "vector fact" [a 1] a => 1 a => 1))
+
+(defn z [x] )
+(causes-validation-error #"background cannot be used inside of formula"
+  (formula [a 1]
+    (background (h 1) => 5)
+    (z a) => 10))
+
+;; Things that should be valid
+
+(defn k [x] (* 2 (h x)))
+(formula "against-backgrounds at the front of the body are fine" [a 1]
+  (against-background (h 1) => 5)
+  (k a) => 10)
+
+
+;; *num-generations-per-formula* binding validation
+
 (defn- gen-int [pred]
-  (rand-nth (filter pred [-5 -4 -3 -2 -1 0 1 2 3 4 5])))
+  (rand-nth (filter pred [-999 -100 -20 -5 -1 0 1 5 20 100 999])))
 
 (formula
   "allows users to dynamically rebind to 1+"
@@ -46,7 +70,7 @@
      => (throws #"must be an integer 1 or greater"))
 
 (formula
-  "binding too smalla value - gives nice error msg"
+  "binding too small a value - gives nice error msg"
   [n (gen-int #(>= % 1))]
   (binding [midje.ideas.formulas/*num-generations-per-formula* n] nil) 
      =not=> (throws Exception))