Start documenting the testing module.

README.md

@@ -92,17 +92,44 @@ Support Modules
 
 ### Testing
 
+This module provides simple syntax forms for (unit) testing of other
+modules.
+
+    (run-tests name body ...)
+
+* ```name``` - identifier describing the module being tested
+* ```body ...``` - test expressions
+
+Runs all tests specified on the ```body ...```. Firstly it prints
+"[test] name " at the beginning of the line. Secondly it runs all
+tests, printing "." for each test successfully passed. If all tests
+pass, prints " ok." and moves the cursor to the next line.
+
+In case any of the tests fails, exception is raised and program
+terminates.
+
+    (test-eq? name expression expected-result)
+
+* ```name``` - identifier representing the name of the test
+* ```expression``` - expression to be evaluated
+* ```expected-result``` - expected result of the test expression
+
+Evaluates the test ```expression``` and compares the result with
+```expected-result``` using ```eq?```. If the comparison fails, an
+exception is raised with the ```name``` of the test added to the
+exception. If the test passes, prints "." like all tests from this
+module do.
+
 ### Utils
 
 To ensure there are no external dependencies (including chicken eggs),
 this module re-implements any basic procedures which are required for
 any algorithms used.
 
-#### Filter
-
     (filter pred? lst)
 
 * ```pred?``` - procedure accepting any value and returning #t or #f
 * ```lst``` - list to be filtered
 
-Returns a list containing only elements matching given ```pred?``` predicate.
+Returns a list containing only elements matching given ```pred?```
+predicate.