diff --git a/rs-tests.rkt b/rs-tests.rkt
deleted file mode 100644
index 616a6ff..0000000
--- a/rs-tests.rkt
+++ /dev/null
@@ -1,91 +0,0 @@
-#lang racket
-
-;;; Tests for dds/rs.
-
-(require rackunit graph "rs.rkt" "utils.rkt")
-
-(test-case "Basic definitions"
-  (let* ([r1 (reaction (set 'x) (set 'y) (set 'z))]
-         [r2 (reaction (set 'x) (set) (set 'y))]
-         [rs (make-immutable-hash (list (cons 'a r1) (cons 'b r2)))]
-         [s1 (set 'x 'z)]
-         [s2 (set 'x 'y)])
-    (check-true (enabled? r1 s1))
-    (check-false (enabled? r1 s2))
-    (check-equal? (list-enabled rs s1) '(a b))
-    (check-equal? (list-enabled rs s2) '(b))
-    (check-equal? (union-products rs '(a b)) (set 'y 'z))
-    (check-equal? (apply-rs rs s1) (set 'y 'z))
-    (check-equal? (apply-rs rs s2) (set 'y))))
-
-(test-case "Org-mode interaction"
-  (check-equal? (ht-str-triples->rs #hash((a . ("x t" "y" "z"))))
-                (make-immutable-hash (list (cons 'a (reaction (set 'x 't) (set 'y) (set 'z))))))
-  (check-equal? (read-context-sequence "((\"x y\") (\"z\") (\"\") (\"t\"))")
-                (list (set 'x 'y) (set 'z) (set) (set 't)))
-  (check-equal? (rs->ht-str-triples (make-immutable-hash (list (cons 'a (reaction (set 'x 't) (set 'y) (set 'z))))))
-                #hash((a . ("t x" "y" "z"))))
-  (check-equal? (read-org-rs "((\"a\" \"x t\" \"y\" \"z\") (\"b\" \"x\" \"q\" \"z\"))")
-                (hash
-                 'a
-                 (reaction (set 'x 't) (set 'y) (set 'z))
-                 'b
-                 (reaction (set 'x) (set 'q) (set 'z)))))
-
-(test-case "Dynamics of reaction systems"
-  (let* ([r1 (reaction (set 'x) (set 'y) (set 'z))]
-         [r2 (reaction (set 'x) (set) (set 'y))]
-         [rs (make-immutable-hash (list (cons 'a r1) (cons 'b r2)))]
-         [dyn (dynamics rs)]
-         [state1 (state (set) (list (set 'x) (set 'y) (set 'z) (set) (set 'z)))]
-         [sgr (dds-build-state-graph-annotated dyn (set state1))]
-         [ip (build-interactive-process-graph rs (list (set 'x) (set 'y) (set 'z) (set) (set 'z)))])
-    (check-equal? (dds-step-one-annotated dyn state1)
-                  (set (cons
-                        (set 'a 'b)
-                        (state (set 'y 'z) (list (set 'y) (set 'z) (set) (set 'z))))))
-    (check-equal? (dds-step-one dyn state1)
-                  (set (state (set 'y 'z) (list (set 'y) (set 'z) (set) (set 'z)))))
-
-    (check-true (has-vertex? sgr (state (set 'y 'z) (list (set 'y) (set 'z) (set) (set 'z)))))
-    (check-true (has-vertex? sgr (state (set) (list (set 'z) (set) (set 'z)))))
-    (check-true (has-vertex? sgr (state (set) (list (set) (set 'z)))))
-    (check-true (has-vertex? sgr (state (set) (list (set 'z)))))
-    (check-true (has-vertex? sgr (state (set) (list (set 'x) (set 'y) (set 'z) (set) (set 'z)))))
-    (check-true (has-vertex? sgr (state (set) '())))
-
-    (check-equal? (edge-weight sgr
-                               (state (set) '())
-                               (state (set) '()))
-                  (set (set)))
-    (check-equal? (edge-weight sgr
-                               (state (set 'y 'z) (list (set 'y) (set 'z) (set) (set 'z)))
-                               (state (set) (list (set 'z) (set) (set 'z))))
-                  (set (set)))
-    (check-equal? (edge-weight sgr
-                               (state (set) (list (set 'z) (set) (set 'z)))
-                               (state (set) (list (set) (set 'z))))
-                  (set (set)))
-    (check-equal? (edge-weight sgr
-                               (state (set) (list (set) (set 'z)))
-                               (state (set) (list (set 'z))))
-                  (set (set)))
-    (check-equal? (edge-weight sgr
-                               (state (set) (list (set 'z)))
-                               (state (set) '()))
-                  (set (set)))
-    (check-equal? (edge-weight sgr
-                               (state (set) (list (set 'x) (set 'y) (set 'z) (set) (set 'z)))
-                               (state (set 'y 'z) (list (set 'y) (set 'z) (set) (set 'z))))
-                  (set (set 'a 'b)))
-
-    (check-equal? sgr ip)
-
-    (check-equal? (build-interactive-process rs (list (set 'x) (set 'y) (set 'z) (set) (set 'z)))
-                  (list
-                   (list (set 'x) (set))
-                   (list (set 'y) (set 'y 'z))
-                   (list (set 'z) (set))
-                   (list (set) (set))
-                   (list (set 'z) (set))
-                   (list (set) (set))))))
diff --git a/rs.rkt b/rs.rkt
index 4c2c6cf..14dd037 100644
--- a/rs.rkt
+++ b/rs.rkt
@@ -35,6 +35,10 @@
  ;; Contracts
  (contract-out [reaction-system/c contract?]))
 
+(module+ test
+  (require rackunit))
+
+
 ;;; =================
 ;;; Basic definitions
 ;;; =================
@@ -81,6 +85,21 @@
   (let ([as (list-enabled rs s)])
     (union-products rs as)))
 
+(module+ test
+  (test-case "Basic definitions"
+    (let* ([r1 (reaction (set 'x) (set 'y) (set 'z))]
+           [r2 (reaction (set 'x) (set) (set 'y))]
+           [rs (make-immutable-hash (list (cons 'a r1) (cons 'b r2)))]
+           [s1 (set 'x 'z)]
+           [s2 (set 'x 'y)])
+      (check-true (enabled? r1 s1))
+      (check-false (enabled? r1 s2))
+      (check-equal? (list-enabled rs s1) '(a b))
+      (check-equal? (list-enabled rs s2) '(b))
+      (check-equal? (union-products rs '(a b)) (set 'y 'z))
+      (check-equal? (apply-rs rs s1) (set 'y 'z))
+      (check-equal? (apply-rs rs s2) (set 'y)))))
+
 
 ;;; ====================
 ;;; Org-mode interaction
@@ -102,13 +121,30 @@
   (for/hash ([(a triple) (in-hash ht)])
     (values a (str-triple->reaction triple))))
 
+(module+ test
+  (check-equal?
+   (ht-str-triples->rs #hash((a . ("x t" "y" "z"))))
+   (make-immutable-hash (list (cons 'a (reaction (set 'x 't) (set 'y) (set 'z)))))))
+
 ;;; Reads a reaction system from an Org-mode style string.
 (define read-org-rs (compose ht-str-triples->rs read-org-variable-mapping))
 
+(module+ test
+  (check-equal? (read-org-rs "((\"a\" \"x t\" \"y\" \"z\") (\"b\" \"x\" \"q\" \"z\"))")
+                (hash
+                 'a
+                 (reaction (set 'x 't) (set 'y) (set 'z))
+                 'b
+                 (reaction (set 'x) (set 'q) (set 'z)))))
+
 ;;; Reads a context sequence from an Org sexp corresponding to a list.
 (define (read-context-sequence str)
   (map (compose list->set read-symbol-list) (flatten (string->any str))))
 
+(module+ test
+  (check-equal? (read-context-sequence "((\"x y\") (\"z\") (\"\") (\"t\"))")
+                (list (set 'x 'y) (set 'z) (set) (set 't))))
+
 ;;; Converts a reaction to a triple of strings.
 (define/match (reaction->str-triple r)
   [((reaction r i p))
@@ -121,6 +157,11 @@
   (for/hash ([(a r) (in-hash rs)])
     (values a (reaction->str-triple r))))
 
+(module+ test
+  (check-equal?
+   (rs->ht-str-triples (make-immutable-hash (list (cons 'a (reaction (set 'x 't) (set 'y) (set 'z))))))
+   #hash((a . ("t x" "y" "z")))))
+
 
 ;;; ============================
 ;;; Dynamics of reaction systems
@@ -198,3 +239,62 @@
 ;;; Pretty prints the state graph of a reaction system.
 (define (pretty-print-state-graph sgr)
   (update-graph sgr #:v-func pretty-print-state #:e-func pretty-print-set-sets))
+
+(module+ test
+  (test-case "Dynamics of reaction systems"
+    (let* ([r1 (reaction (set 'x) (set 'y) (set 'z))]
+           [r2 (reaction (set 'x) (set) (set 'y))]
+           [rs (make-immutable-hash (list (cons 'a r1) (cons 'b r2)))]
+           [dyn (dynamics rs)]
+           [state1 (state (set) (list (set 'x) (set 'y) (set 'z) (set) (set 'z)))]
+           [sgr (dds-build-state-graph-annotated dyn (set state1))]
+           [ip (build-interactive-process-graph rs (list (set 'x) (set 'y) (set 'z) (set) (set 'z)))])
+      (check-equal? (dds-step-one-annotated dyn state1)
+                    (set (cons
+                          (set 'a 'b)
+                          (state (set 'y 'z) (list (set 'y) (set 'z) (set) (set 'z))))))
+      (check-equal? (dds-step-one dyn state1)
+                    (set (state (set 'y 'z) (list (set 'y) (set 'z) (set) (set 'z)))))
+
+      (check-true (has-vertex? sgr (state (set 'y 'z) (list (set 'y) (set 'z) (set) (set 'z)))))
+      (check-true (has-vertex? sgr (state (set) (list (set 'z) (set) (set 'z)))))
+      (check-true (has-vertex? sgr (state (set) (list (set) (set 'z)))))
+      (check-true (has-vertex? sgr (state (set) (list (set 'z)))))
+      (check-true (has-vertex? sgr (state (set) (list (set 'x) (set 'y) (set 'z) (set) (set 'z)))))
+      (check-true (has-vertex? sgr (state (set) '())))
+
+      (check-equal? (edge-weight sgr
+                                 (state (set) '())
+                                 (state (set) '()))
+                    (set (set)))
+      (check-equal? (edge-weight sgr
+                                 (state (set 'y 'z) (list (set 'y) (set 'z) (set) (set 'z)))
+                                 (state (set) (list (set 'z) (set) (set 'z))))
+                    (set (set)))
+      (check-equal? (edge-weight sgr
+                                 (state (set) (list (set 'z) (set) (set 'z)))
+                                 (state (set) (list (set) (set 'z))))
+                    (set (set)))
+      (check-equal? (edge-weight sgr
+                                 (state (set) (list (set) (set 'z)))
+                                 (state (set) (list (set 'z))))
+                    (set (set)))
+      (check-equal? (edge-weight sgr
+                                 (state (set) (list (set 'z)))
+                                 (state (set) '()))
+                    (set (set)))
+      (check-equal? (edge-weight sgr
+                                 (state (set) (list (set 'x) (set 'y) (set 'z) (set) (set 'z)))
+                                 (state (set 'y 'z) (list (set 'y) (set 'z) (set) (set 'z))))
+                    (set (set 'a 'b)))
+
+      (check-equal? sgr ip)
+
+      (check-equal? (build-interactive-process rs (list (set 'x) (set 'y) (set 'z) (set) (set 'z)))
+                    (list
+                     (list (set 'x) (set))
+                     (list (set 'y) (set 'y 'z))
+                     (list (set 'z) (set))
+                     (list (set) (set))
+                     (list (set 'z) (set))
+                     (list (set) (set)))))))