From b6202d7091965f9b4785ef6722fca31474c6c98f Mon Sep 17 00:00:00 2001
From: Eduardo Julian
Date: Wed, 30 Jan 2019 09:28:51 -0400
Subject: Tests are now first class.

---
 lux-mode/lux-mode.el       |   2 +-
 stdlib/source/lux/test.lux | 308 +++++++++++----------------------
 stdlib/test/test/lux.lux   | 418 ++++++++++++++++++++++++---------------------
 stdlib/test/tests.lux      |  24 +--
 4 files changed, 340 insertions(+), 412 deletions(-)

diff --git a/lux-mode/lux-mode.el b/lux-mode/lux-mode.el
index 8825438c7..46d0e77fe 100644
--- a/lux-mode/lux-mode.el
+++ b/lux-mode/lux-mode.el
@@ -299,7 +299,7 @@ Called by `imenu--generic-function'."
                     remember
                     ;;;;;;;;;;;;;;;;;;;;;;;;
                     "\\.module:"
-                    "def:" "type:" "program:" "context:"
+                    "def:" "type:" "program:"
                     "macro:" "syntax:"
                     "with-expansions"
                     "exception:"
diff --git a/stdlib/source/lux/test.lux b/stdlib/source/lux/test.lux
index ea4e9b6de..f0ab87249 100644
--- a/stdlib/source/lux/test.lux
+++ b/stdlib/source/lux/test.lux
@@ -1,267 +1,161 @@
 (.module: {#.doc "Tools for unit & property-based/generative testing."}
-  [lux #*
+  [lux (#- and)
    [control
-    ["." monad (#+ do Monad)]
-    ["p" parser]
+    ["." monad (#+ Monad do)]
+    ["ex" exception (#+ exception:)]
     [concurrency
-     ["." process]
-     ["." promise (#+ Promise)]]]
+     ["." promise (#+ Promise) ("promise/." Monad<Promise>)]]]
    [data
     ["." product]
-    ["." maybe]
-    ["e" error]
     ["." text
      format]
     [collection
-     ["." list ("list/." Monad<List> Fold<List>)]]]
+     ["." list ("list/." Functor<List>)]]]
    [time
     ["." instant]
     ["." duration]]
    [math
-    ["r" random]]
-   ["." macro (#+ with-gensyms)
-    ["s" syntax (#+ syntax: Syntax)]
-    ["." code]]
-   ["." io (#+ IO io)]])
+    ["r" random ("random/." Monad<Random>)]]
+   ["." io]])
 
-## [Types]
-(type: #export Counters [Nat Nat])
+(type: #export Counters
+  {#successes Nat
+   #failures Nat})
 
-(type: #export Seed
-  {#.doc "The seed value used for random testing (if that feature is used)."}
-  (I64 Any))
+(def: (add-counters parameter subject)
+  (-> Counters Counters Counters)
+  {#successes (n/+ (get@ #successes parameter) (get@ #successes subject))
+   #failures (n/+ (get@ #failures parameter) (get@ #failures subject))})
+
+(def: start
+  Counters
+  {#successes 0
+   #failures 0})
+
+(do-template [<name> <category>]
+  [(def: <name> Counters (update@ <category> .inc start))]
+
+  [success #successes]
+  [failure #failures]
+  )
 
 (type: #export Test
   (r.Random (Promise [Counters Text])))
 
-(def: pcg-32-magic-inc Nat 12345)
+(def: separator text.new-line)
 
-## [Values]
-(def: success Counters [1 0])
-(def: failure Counters [0 1])
-(def: start Counters [0 0])
+(def: #export (and left right)
+  {#.doc "Sequencing combinator."}
+  (-> Test Test Test)
+  (do r.Monad<Random>
+    [left left
+     right right]
+    (wrap (do promise.Monad<Promise>
+            [[l-counter l-documentation] left
+             [r-counter r-documentation] right]
+            (wrap [(add-counters l-counter r-counter)
+                   (format l-documentation ..separator r-documentation)])))))
 
-(def: (add-counters [s f] [ts tf])
-  (-> Counters Counters Counters)
-  [(n/+ s ts) (n/+ f tf)])
+(def: context-prefix text.tab)
+
+(def: #export (context description)
+  (-> Text Test Test)
+  (random/map (promise/map (function (_ [counters documentation])
+                             [counters (|> documentation
+                                           (text.split-all-with ..separator)
+                                           (list/map (|>> (format context-prefix)))
+                                           (text.join-with ..separator)
+                                           (format description ..separator))]))))
+
+(def: failure-prefix "  [Error] ")
+(def: success-prefix "[Success] ")
 
-(def: #export (fail message)
-  (All [a] (-> Text Test))
-  (|> [failure (format "  [Error] " message)]
-      (:: promise.Monad<Promise> wrap)
-      (:: r.Monad<Random> wrap)))
+(def: #export fail
+  (-> Text Test)
+  (|>> (format ..failure-prefix)
+       [failure]
+       promise/wrap
+       random/wrap))
 
 (def: #export (assert message condition)
   {#.doc "Check that a condition is #1, and fail with the given message otherwise."}
   (-> Text Bit (Promise [Counters Text]))
-  (<| (:: promise.Monad<Promise> wrap)
+  (<| promise/wrap
       (if condition
-        [success (format "[Success] " message)]
-        [failure (format "  [Error] " message)])))
+        [success (format ..success-prefix message)]
+        [failure (format ..failure-prefix message)])))
 
 (def: #export (test message condition)
   {#.doc "Check that a condition is #1, and fail with the given message otherwise."}
   (-> Text Bit Test)
   (:: r.Monad<Random> wrap (assert message condition)))
 
-(def: (run' tests)
-  (-> (List [Text (IO Test) Text]) (Promise Counters))
-  (do promise.Monad<Promise>
-    [test-runs (|> tests
-                   (list/map (: (-> [Text (IO Test) Text] (Promise Counters))
-                                (function (_ [module test description])
-                                  (do @
-                                    [#let [pre (io.run instant.now)]
-                                     [counters documentation] (|> (io.run test)
-                                                                  (r.run (r.pcg-32 [pcg-32-magic-inc
-                                                                                    (instant.to-millis pre)]))
-                                                                  product.right)
-                                     #let [post (io.run instant.now)
-                                           _ (log! (format "@ " module " "
-                                                           "(" (%duration (instant.span pre post)) ")"
-                                                           text.new-line
-                                                           description text.new-line
-                                                           text.new-line documentation text.new-line))]]
-                                    (wrap counters)))))
-                   (monad.seq @))]
-    (wrap (list/fold add-counters start test-runs))))
+(def: pcg-32-magic-inc Nat 12345)
 
-(def: failed?
-  (-> Counters Bit)
-  (|>> product.right (n/> 0)))
+(type: #export Seed
+  {#.doc "The seed value used for random testing (if that feature is used)."}
+  Nat)
 
 (def: #export (seed value test)
   (-> Seed Test Test)
   (function (_ prng)
-    (let [[_ result] (r.run (r.pcg-32 [pcg-32-magic-inc value])
+    (let [[_ result] (r.run (r.pcg-32 [..pcg-32-magic-inc value])
                             test)]
       [prng result])))
 
+(def: failed?
+  (-> Counters Bit)
+  (|>> product.right (n/> 0)))
+
 (def: (times-failure seed documentation)
-  (-> (I64 Any) Text Text)
-  (format "Failed with this seed: " (%n (.nat seed)) text.new-line
-          documentation))
+  (-> Seed Text Text)
+  (format documentation ..separator ..separator
+          "Failed with this seed: " (%n seed)))
+
+(exception: #export (must-try-test-at-least-once) "")
 
 (def: #export (times amount test)
   (-> Nat Test Test)
   (cond (n/= 0 amount)
-        (fail "Cannot try a test 0 times.")
+        (fail (ex.construct must-try-test-at-least-once []))
 
         (n/= 1 amount)
         test
 
         ## else
         (do r.Monad<Random>
-          [seed r.i64]
+          [seed r.nat]
           (function (_ prng)
-            (let [[prng' instance] (r.run (r.pcg-32 [pcg-32-magic-inc seed]) test)]
+            (let [[prng' instance] (r.run (r.pcg-32 [..pcg-32-magic-inc seed]) test)]
               [prng' (do promise.Monad<Promise>
                        [[counters documentation] instance]
                        (if (failed? counters)
                          (wrap [counters (times-failure seed documentation)])
                          (product.right (r.run prng' (times (dec amount) test)))))])))))
 
-## [Syntax]
-(syntax: #export (context: description test)
-  {#.doc (doc "Macro for definint tests."
-              (context: "Simple macros and constructs"
-                ($_ seq
-                    (test "Can write easy loops for iterative programming."
-                          (i/= +1000
-                               (loop [counter +0
-                                      value +1]
-                                 (if (i/< +3 counter)
-                                   (recur (inc counter) (i/* +10 value))
-                                   value))))
-
-                    (test "Can create lists easily through macros."
-                          (and (case (list +1 +2 +3)
-                                 (#.Cons +1 (#.Cons +2 (#.Cons +3 #.Nil)))
-                                 #1
-
-                                 _
-                                 #0)
-                               
-                               (case (list& +1 +2 +3 (list +4 +5 +6))
-                                 (#.Cons +1 (#.Cons +2 (#.Cons +3 (#.Cons +4 (#.Cons +5 (#.Cons +6 #.Nil))))))
-                                 #1
-
-                                 _
-                                 #0)))
-
-                    (test "Can have defaults for Maybe values."
-                          (and (is? "yolo" (maybe.default "yolo"
-                                                          #.None))
-                               
-                               (is? "lol" (maybe.default "yolo"
-                                                         (#.Some "lol")))))
-                    ))
-              
-              "Also works with random generation of values for property-based testing."
-              (context: "Addition & Substraction"
-                (do @
-                  [x (:: @ map <prep> rand-gen)
-                   y (:: @ map <prep> rand-gen)]
-                  (test ""
-                        (and (|> x (- y) (+ y) (= x))
-                             (|> x (+ y) (- y) (= x))))))
-              
-              "By default, random tests will be tried 100 times, you can specify the amount you want:"
-              (context: "Addition & Substraction"
-                (<| (times 1234)
-                    (do @
-                      [x (:: @ map <prep> rand-gen)
-                       y (:: @ map <prep> rand-gen)]
-                      (test ""
-                            (and (|> x (- y) (+ y) (= x))
-                                 (|> x (+ y) (- y) (= x)))))))
-              
-              "If a test fails, you'll be shown a seed that you can then use to reproduce a failing scenario."
-              (context: "Addition & Substraction"
-                (<| (seed 987654321)
-                    (do @
-                      [x (:: @ map <prep> rand-gen)
-                       y (:: @ map <prep> rand-gen)]
-                      (test ""
-                            (and (|> x (- y) (+ y) (= x))
-                                 (|> x (+ y) (- y) (= x)))))))
-              )}
-  (with-gensyms [g!context g!test g!error]
-    (wrap (list (` (def: #export (~ g!context)
-                     {#..test ((~! code.text) (~ description))}
-                     (~! (IO Test))
-                     ((~! io) (case ("lux try" ((~! io) ((~! do)
-                                                         (~! r.Monad<Random>)
-                                                         []
-                                                         (~ test))))
-                                (#.Right (~ g!test))
-                                (~ g!test)
-
-                                (#.Left (~ g!error))
-                                (..fail (~ g!error))))))))))
-
-(def: (exported-tests module-name)
-  (-> Text (Meta (List [Text Text Text])))
-  (do macro.Monad<Meta>
-    [defs (macro.exports module-name)]
-    (wrap (|> defs
-              (list/map (function (_ [def-name [_ def-anns _]])
-                          (case (macro.get-text-ann (name-of #..test) def-anns)
-                            (#.Some description)
-                            [#1 module-name def-name description]
+(def: (tally counters)
+  (-> Counters Text)
+  (let [successes (get@ #successes counters)
+        failures (get@ #failures counters)]
+    (ex.report ["Tests" (%n (n/+ successes failures))]
+               ["Successes" (%n successes)]
+               ["Failures" (%n failures)])))
 
-                            _
-                            [#0 module-name def-name ""])))
-              (list.filter product.left)
-              (list/map product.right)))))
+(def: failure-exit-code -1)
+(def: success-exit-code +0)
 
-(def: (success-message successes failures)
-  (-> Nat Nat Text)
-  (format "Test-suite finished." text.new-line
-          (%n successes) " out of " (%n (n/+ failures successes)) " tests passed." text.new-line
-          (%n failures) " tests failed." text.new-line))
-
-(syntax: #export (run)
-  {#.doc (doc "Runs all the tests defined on the current module, and in all imported modules."
-              (run))}
-  (with-gensyms [g!successes g!failures g!total-successes g!total-failures]
-    (do @
-      [current-module macro.current-module-name
-       modules (macro.imported-modules current-module)
-       tests (: (Meta (List [Text Text Text]))
-                (|> modules
-                    (#.Cons current-module)
-                    list.reverse
-                    (monad.map @ exported-tests)
-                    (:: @ map list/join)))]
-      (wrap (list (` (: (~! (IO Any))
-                        ((~! io) (exec ((~! do) (~! promise.Monad<Promise>)
-                                        [(~' #let) [(~ g!total-successes) 0
-                                                    (~ g!total-failures) 0]
-                                         (~+ (|> tests
-                                                 (list/map (function (_ [module-name test desc])
-                                                             (` [(~ (code.text module-name)) (~ (code.identifier [module-name test])) (~ (code.text desc))])))
-                                                 (list.split-all process.parallelism)
-                                                 (list/map (function (_ group)
-                                                             (list (` [(~ g!successes) (~ g!failures)]) (` ((~! run') (list (~+ group))))
-                                                                   (' #let) (` [(~ g!total-successes) (n/+ (~ g!successes) (~ g!total-successes))
-                                                                                (~ g!total-failures) (n/+ (~ g!failures) (~ g!total-failures))]))))
-                                                 list/join))]
-                                        (exec (log! ((~! success-message) (~ g!total-successes) (~ g!total-failures)))
-                                          ((~! promise.future)
-                                           ((~! io.exit) (if (n/> 0 (~ g!total-failures))
-                                                           +1
-                                                           +0)))))
-                                   [])))))))))
-
-(def: #export (seq left right)
-  {#.doc "Sequencing combinator."}
-  (-> Test Test Test)
-  (do r.Monad<Random>
-    [left left
-     right right]
-    (wrap (do promise.Monad<Promise>
-            [[l-counter l-documentation] left
-             [r-counter r-documentation] right]
-            (wrap [(add-counters l-counter r-counter)
-                   (format l-documentation text.new-line r-documentation)])))))
+(def: #export (run! test)
+  (-> Test (Promise Nothing))
+  (do promise.Monad<Promise>
+    [pre (promise.future instant.now)
+     #let [seed (instant.to-millis pre)
+           prng (r.pcg-32 [..pcg-32-magic-inc seed])]
+     [counters documentation] (|> test (r.run prng) product.right)
+     post (promise.future instant.now)
+     #let [duration (instant.span pre post)
+           _ (log! (format documentation text.new-line text.new-line
+                           "(" (%duration duration) ")" text.new-line
+                           (tally counters)))]]
+    (promise.future (io.exit (case (get@ #failures counters)
+                               0 ..success-exit-code
+                               _ ..failure-exit-code)))))
diff --git a/stdlib/test/test/lux.lux b/stdlib/test/test/lux.lux
index 61a0299ea..0ed5cbc2a 100644
--- a/stdlib/test/test/lux.lux
+++ b/stdlib/test/test/lux.lux
@@ -1,208 +1,240 @@
 (.module:
   [lux #*
    [control
-    [monad (#+ do)]]
+    [monad (#+ do)]
+    [predicate (#+ Predicate)]]
    [data
     ["." maybe]
     [number
-     ["." i64]]
-    [text ("text/." Equivalence<Text>)
-     format]]
+     ["." i64]]]
    ["." math
-    ["r" random]]
-   ["." macro
-    ["s" syntax (#+ syntax:)]]
-   test])
-
-(context: "Value identity."
-  (<| (times 100)
-      (do @
-        [size (|> r.nat (:: @ map (|>> (n/% 100) (n/max 10))))
-         x (r.unicode size)
-         y (r.unicode size)]
-        ($_ seq
-            (test "Every value is identical to itself, and the 'id' function doesn't change values in any way."
-                  (and (is? x x)
-                       (is? x (id x))))
-
-            (test "Values created separately can't be identical."
-                  (not (is? x y)))
-            ))))
-
-(do-template [category rand-gen even? odd? = < >]
-  [(context: (format "[" category "] " "Simple operations.")
-     (<| (times 100)
-         (do @
-           [value rand-gen]
-           ($_ seq
-               (test (format "[" category "] " "Moving up-down or down-up should result in same value.")
-                     (and (|> value inc dec (= value))
-                          (|> value dec inc (= value))))
-               (test (format "[" category "] " "(x1) > x && (x-1) < x")
-                     (and (|> value inc (> value))
-                          (|> value dec (< value))))
-               (test (format "[" category "] " "Every odd/even number is surrounded by two of the other kind.")
-                     (if (even? value)
-                       (and (|> value inc odd?)
-                            (|> value dec odd?))
-                       (and (|> value inc even?)
-                            (|> value dec even?))))))))]
-
-  ["Nat" r.nat n/even? n/odd? n/= n/< n/>]
-  ["Int" r.int i/even? i/odd? i/= i/< i/>]
-  )
-
-(do-template [category rand-gen = < > <= >= min max]
-  [(context: (format "[" category "] " "(More) simple operations.")
-     (<| (times 100)
-         (do @
-           [x rand-gen
-            y rand-gen]
-           (seq (test (format "[" category "] " "The symmetry of numerical comparisons.")
-                      (or (= x y)
-                          (if (< y x)
-                            (> x y)
-                            (< x y))))
-                (test (format "[" category "] " "Minimums and maximums.")
-                      (and (and (<= x (min x y))
-                                (<= y (min x y)))
-                           (and (>= x (max x y))
-                                (>= y (max x y)))))))))]
-
-  ["Int"  r.int  i/= i/< i/> i/<= i/>= i/min i/max]
-  ["Nat"  r.nat  n/= n/< n/> n/<= n/>= n/min n/max]
-  ["Frac" r.frac f/= f/< f/> f/<= f/>= f/min f/max]
-  ["Rev"  r.rev  r/= r/< r/> r/<= r/>= r/min r/max]
-  )
-
-(do-template [category rand-gen = + - * / <%> > <0> <1> <factor> <cap> <prep>]
-  [(context: (format "[" category "] " "Additive identity")
-     (<| (times 100)
-         (do @
-           [x rand-gen]
-           (test ""
-                 (and (|> x (+ <0>) (= x))
-                      (|> x (- <0>) (= x)))))))
-
-   (context: (format "[" category "] " "Addition & Substraction")
-     (<| (times 100)
-         (do @
-           [x (:: @ map <prep> rand-gen)
-            y (:: @ map <prep> rand-gen)
-            #let [x (* <factor> x)
-                  y (* <factor> y)]]
-           (test ""
-                 (and (|> x (- y) (+ y) (= x))
-                      (|> x (+ y) (- y) (= x)))))))
-
-   (context: (format "[" category "] " "Multiplicative identity")
-     (<| (times 100)
-         (do @
-           [x rand-gen]
-           (test ""
-                 ## Skip this test for Rev
-                 ## because Rev division loses the last
-                 ## 32 bits of precision.
-                 (or (text/= "Rev" category)
-                     (and (|> x (* <1>) (= x))
-                          (|> x (/ <1>) (= x))))))))
-
-   (context: (format "[" category "] " "Multiplication & Division")
-     (<| (times 100)
-         (do @
-           [x (:: @ map <cap> rand-gen)
-            y (|> rand-gen
-                  (:: @ map <cap>)
-                  (r.filter (|>> (= <0>) not)))
-            #let [r (<%> y x)
-                  x' (- r x)]]
-           (test ""
-                 ## Skip this test for Rev
-                 ## because Rev division loses the last
-                 ## 32 bits of precision.
-                 (or (text/= "Rev" category)
-                     (or (> x' y)
-                         (|> x' (/ y) (* y) (= x'))))
-                 ))))]
-
-  ["Nat"  r.nat  n/= n/+ n/- n/* n// n/% n/> 0  1        1_000_000   (n/% 1_000) id]
-  ["Int"  r.int  i/= i/+ i/- i/* i// i/% i/>  +0   +1         +1_000_000   (i/%  +1_000) id]
-  ["Frac" r.frac f/= f/+ f/- f/* f// f/% f/>  +0.0 +1.0       +1_000_000.0 id           math.floor]
-  ["Rev"  r.rev  r/= r/+ r/- r/* r// r/% r/>   .0 (.rev -1) (.rev -1)   id           id]
-  )
+    ["r" random (#+ Random) ("r/." Functor<Random>)]]
+   ["_" test (#+ Test)]])
+
+(def: identity
+  Test
+  (do r.Monad<Random>
+    [self (r.unicode 1)]
+    ($_ _.and
+        (_.test "Every value is identical to itself."
+                (is? self self))
+        (_.test "The 'id' function doesn't change values in any way."
+                (is? self (id self)))
+        (do @
+          [other (r.unicode 1)]
+          (_.test "Values created separately can't be identical."
+                  (not (is? self other))))
+        )))
+
+(def: increment-and-decrement
+  Test
+  (do r.Monad<Random>
+    [value r.i64]
+    ($_ _.and
+        (_.test "'inc' and 'dec' are different."
+                (not (n/= (inc value)
+                          (dec value))))
+        (_.test "'inc' and 'dec' are opposites."
+                (and (|> value inc dec (n/= value))
+                     (|> value dec inc (n/= value))))
+        (_.test "'inc' and 'dec' shift the number by 1."
+                (let [shift 1]
+                  (and (n/= (n/+ shift value)
+                            (inc value))
+                       (n/= (n/- shift value)
+                            (dec value))))))))
+
+(def: (check-neighbors has-property? value)
+  (All [a] (-> (Predicate (I64 a)) (I64 a) Bit))
+  (and (|> value inc has-property?)
+       (|> value dec has-property?)))
+
+(def: (even-or-odd rand-gen even? odd?)
+  (All [a] (-> (Random (I64 a)) (Predicate (I64 a)) (Predicate (I64 a)) Test))
+  (do r.Monad<Random>
+    [value rand-gen]
+    ($_ _.and
+        (_.test "Every number is either even or odd."
+                (if (even? value)
+                  (not (odd? value))
+                  (odd? value)))
+        (_.test "Every odd/even number is surrounded by two of the other kind."
+                (if (even? value)
+                  (check-neighbors odd? value)
+                  (check-neighbors even? value))))))
+
+(type: (Choice a)
+  (-> a a a))
+
+(type: (Order a)
+  (-> a a Bit))
+
+(type: (Equivalence a)
+  (-> a a Bit))
+
+(def: (choice rand-gen = [< choose])
+  (All [a] (-> (Random a) (Equivalence a) [(Order a) (Choice a)] Test))
+  (do r.Monad<Random>
+    [left rand-gen
+     right rand-gen
+     #let [choice (choose left right)]]
+    ($_ _.and
+        (_.test "The choice between 2 values is one of them."
+                (or (= left choice)
+                    (= right choice)))
+        (_.test "The choice between 2 values implies an order relationship between them."
+                (if (= left choice)
+                  (< right choice)
+                  (< left choice))))))
+
+(def: (minimum-and-maximum rand-gen = min' max')
+  (All [a] (-> (Random a) (Equivalence a) [(Order a) (Choice a)] [(Order a) (Choice a)] Test))
+  ($_ _.and
+      (<| (_.context "Minimum.")
+          (choice rand-gen = min'))
+      (<| (_.context "Maximum.")
+          (choice rand-gen = max'))))
+
+(def: (conversion rand-gen forward backward =)
+  (All [a b] (-> (Random a) (-> a b) (-> b a) (Equivalence a) Test))
+  (do r.Monad<Random>
+    [value rand-gen]
+    (_.test "Can convert between types in a lossless way."
+            (|> value forward backward (= value)))))
 
 (def: frac-rev
   (r.Random Rev)
   (|> r.rev
       (:: r.Functor<Random> map (|>> (i64.left-shift 11) (i64.logical-right-shift 11)))))
 
-(do-template [category rand-gen -> <- = <cap>]
-  [(context: (format "[" category "] " "Numeric conversions")
-     (<| (times 100)
-         (do @
-           [value rand-gen
-            #let [value (<cap> value)]]
-           (test ""
-                 (|> value -> <- (= value))))))]
-
-  ["Int->Nat"  r.int    .nat        .int        i/= (i/%  +1_000_000)]
-  ["Nat->Int"  r.nat    .int        .nat        n/= (n/% 1_000_000)]
-  ["Int->Frac" r.int    int-to-frac frac-to-int i/= (i/%  +1_000_000)]
-  ["Frac->Int" r.frac   frac-to-int int-to-frac f/= math.floor]
-  ["Rev->Frac" frac-rev rev-to-frac frac-to-rev r/= id]
-  )
-
-(context: "Simple macros and constructs"
-  ($_ seq
-      (test "Can write easy loops for iterative programming."
-            (i/= +1000
-                 (loop [counter +0
-                        value +1]
-                   (if (i/< +3 counter)
-                     (recur (inc counter) (i/* +10 value))
-                     value))))
-
-      (test "Can create lists easily through macros."
-            (and (case (list +1 +2 +3)
-                   (#.Cons +1 (#.Cons +2 (#.Cons +3 #.Nil)))
-                   #1
-
-                   _
-                   #0)
-                 
-                 (case (list& +1 +2 +3 (list +4 +5 +6))
-                   (#.Cons +1 (#.Cons +2 (#.Cons +3 (#.Cons +4 (#.Cons +5 (#.Cons +6 #.Nil))))))
-                   #1
-
-                   _
-                   #0)))
-
-      (test "Can have defaults for Maybe values."
-            (and (is? "yolo" (maybe.default "yolo"
-                                            #.None))
-                 
-                 (is? "lol" (maybe.default "yolo"
-                                           (#.Some "lol")))))
+(def: prelude-macros
+  Test
+  ($_ _.and
+      (do r.Monad<Random>
+        [factor (r/map (|>> (n/% 10) (n/max 1)) r.nat)
+         iterations (r/map (n/% 100) r.nat)
+         #let [expected (n/* factor iterations)]]
+        (_.test "Can write loops."
+                (n/= expected
+                     (loop [counter 0
+                            value 0]
+                       (if (n/< iterations counter)
+                         (recur (inc counter) (n/+ factor value))
+                         value)))))
+
+      (do r.Monad<Random>
+        [first r.nat
+         second r.nat
+         third r.nat]
+        (_.test "Can create lists easily through macros."
+                (and (case (list first second third)
+                       (#.Cons first' (#.Cons second' (#.Cons third' #.Nil)))
+                       (and (n/= first first')
+                            (n/= second second')
+                            (n/= third third'))
+
+                       _
+                       false)
+                     (case (list& first (list second third))
+                       (#.Cons first' (#.Cons second' (#.Cons third' #.Nil)))
+                       (and (n/= first first')
+                            (n/= second second')
+                            (n/= third third'))
+
+                       _
+                       false)
+                     (case (list& first second (list third))
+                       (#.Cons first' (#.Cons second' (#.Cons third' #.Nil)))
+                       (and (n/= first first')
+                            (n/= second second')
+                            (n/= third third'))
+
+                       _
+                       false))))
+      (do r.Monad<Random>
+        [default r.nat
+         maybe r.nat]
+        (_.test "Can have defaults for Maybe values."
+                (and (is? default (maybe.default default
+                                                 #.None))
+
+                     (is? maybe (maybe.default default
+                                               (#.Some maybe))))))
       ))
 
-(template: (hypotenuse x y)
-  (i/+ (i/* x x) (i/* y y)))
-
-(context: "Templates."
-  (<| (times 100)
-      (do @
-        [x r.int
-         y r.int]
-        (test "Template application is a stand-in for the templated code."
-              (i/= (i/+ (i/* x x) (i/* y y))
-                   (hypotenuse x y))))))
-
-(context: "Cross-platform support."
-  ($_ seq
-      (test "Can provide default in case there is no particular platform support."
-            (for {"" #0}
-                 #1))
-      (test "Can pick code depending on the platform being targeted."
-            (for {"JVM" #1
-                  "JS" #1}
-                 #0))))
+(template: (hypotenuse cat0 cat1)
+  (n/+ (n/* cat0 cat0) (n/* cat1 cat1)))
+
+(def: template
+  Test
+  (do r.Monad<Random>
+    [cat0 r.nat
+     cat1 r.nat]
+    (_.test "Template application is a stand-in for the templated code."
+            (n/= (n/+ (n/* cat0 cat0) (n/* cat1 cat1))
+                 (hypotenuse cat0 cat1)))))
+
+(def: cross-platform-support
+  Test
+  (do r.Monad<Random>
+    [on-default r.nat
+     on-fake-host r.nat
+     on-valid-host r.nat]
+    ($_ _.and
+        (_.test "Can provide default in case there is no particular host/platform support."
+                (n/= on-default
+                     (for {"" on-fake-host}
+                          on-default)))
+        (_.test "Can pick code depending on the host/platform being targeted."
+                (n/= on-valid-host
+                     (for {"JVM" on-valid-host
+                           "JS" on-valid-host}
+                          on-default))))))
+
+(def: #export test
+  ($_ _.and
+      (<| (_.context "Identity.")
+          ..identity)
+      (<| (_.context "Increment & decrement.")
+          ..increment-and-decrement)
+      (<| (_.context "Even or odd.")
+          ($_ _.and
+              (<| (_.context "Natural numbers.")
+                  (..even-or-odd r.nat n/even? n/odd?))
+              (<| (_.context "Integers.")
+                  (..even-or-odd r.int i/even? i/odd?))))
+      (<| (_.context "Minimum and maximum.")
+          (`` ($_ _.and
+                  (~~ (do-template [<=> <lt> <min> <gt> <max> <gen> <context>]
+                        [(<| (_.context <context>)
+                             (..minimum-and-maximum <gen> <=> [<lt> <min>] [<gt> <max>]))]
+
+                        [i/= i/< i/min i/> i/max r.int "Integers."]
+                        [n/= n/< n/min n/> n/max r.nat "Natural numbers."]
+                        [r/= r/< r/min r/> r/max r.rev "Revolutions."]
+                        [f/= f/< f/min f/> f/max r.frac "Fractions."]
+                        )))))
+      (<| (_.context "Conversion.")
+          (`` ($_ _.and
+                  (~~ (do-template [<context> <=> <forward> <backward> <gen>]
+                        [(<| (_.context <context>)
+                             (..conversion <gen> <forward> <backward> <=>))]
+
+                        ["Int -> Nat"
+                         i/= .nat        .int        (r/map (i/%  +1_000_000) r.int)]
+                        ["Nat -> Int"
+                         n/= .int        .nat        (r/map (n/% 1_000_000) r.nat)]
+                        ["Int -> Frac"
+                         i/= int-to-frac frac-to-int (r/map (i/%  +1_000_000) r.int)]
+                        ["Frac -> Int"
+                         f/= frac-to-int int-to-frac (r/map math.floor r.frac)]
+                        ["Rev -> Frac"
+                         r/= rev-to-frac frac-to-rev frac-rev]
+                        )))))
+      (<| (_.context "Prelude macros.")
+          ..prelude-macros)
+      (<| (_.context "Templates.")
+          ..template)
+      (<| (_.context "Cross-platform support.")
+          ..cross-platform-support)
+      ))
diff --git a/stdlib/test/tests.lux b/stdlib/test/tests.lux
index a5c6919c5..738ef182b 100644
--- a/stdlib/test/tests.lux
+++ b/stdlib/test/tests.lux
@@ -1,7 +1,8 @@
 (.module:
   [lux #*
    [cli (#+ program:)]
-   ["." test]
+   ["." io (#+ io)]
+   ["_" test]
 
    ## These modules do not need to be tested.
    [type
@@ -81,12 +82,11 @@
    ]
   ## TODO: Must have 100% coverage on tests.
   [test
-   ## [lux (#+)]
-   [lux
+   ["/." lux
     ## [cli (#+)]
     ## [host (#+)]
-    [host
-     [jvm (#+)]]
+    ## [host
+    ##  [jvm (#+)]]
     ## [io (#+)]
     ## [time
     ##  [instant (#+)]
@@ -164,11 +164,11 @@
     ##  [poly
     ##   ["poly_." equivalence]
     ##   ["poly_." functor]]]
-    [type ## (#+)
-     ## [check (#+)]
-     ## [implicit (#+)] ## TODO: FIX Specially troublesome...
-     ## [resource (#+)]
-     [dynamic (#+)]]
+    ## [type ## (#+)
+    ##  ## [check (#+)]
+    ##  ## [implicit (#+)] ## TODO: FIX Specially troublesome...
+    ##  ## [resource (#+)]
+    ##  [dynamic (#+)]]
     ## [compiler
     ##  [default
     ##   ["_default/." syntax]
@@ -196,4 +196,6 @@
   )
 
 (program: args
-  (test.run))
+  (exec (_.run! (<| (_.times 100)
+                    /lux.test))
+    (io [])))
-- 
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