diff --git a/functional-tests/dmtest b/functional-tests/dmtest
new file mode 100755
index 0000000..072eb2d
--- /dev/null
+++ b/functional-tests/dmtest
@@ -0,0 +1,12 @@
+#! /usr/bin/scheme-script
+
+(import (rnrs)
+        (test-runner)
+	(bcache bcache-tests)
+	(device-mapper dm-tests))
+
+(register-bcache-tests)
+(register-dm-tests)
+
+(run-tests)
+
diff --git a/functional-tests/run-tests b/functional-tests/run-tests
index c08f40f..8def1f7 100755
--- a/functional-tests/run-tests
+++ b/functional-tests/run-tests
@@ -1,185 +1,14 @@
 #! /usr/bin/scheme-script
 
 (import (rnrs)
-        (only (chezscheme) load-shared-object)
-        (fmt fmt)
-        (list-utils)
-        (functional-tests)
-	(bcache bcache-tests)
+        (test-runner)
         (cache-functional-tests)
         (era-functional-tests)
-        (parser-combinators)
-        (only (srfi s1 lists) break)
-        (regex)
-        (srfi s8 receive)
-	(temp-file)
         (thin-functional-tests))
 
-;;------------------------------------------------
-
-;; Returns #t if the xs list matches prefix
-(define (begins-with prefix xs)
-  (cond
-    ((null? prefix) #t)
-    ((null? xs) #f)
-    ((eq? (car prefix) (car xs))
-     (begins-with (cdr prefix) (cdr xs)))
-    (else #f)))
-
-(define (split-list xs sep)
-  (define (safe-cdr xs)
-    (if (null? xs) '() (cdr xs)))
-
-  (if (null? xs)
-      '()
-      (receive (p r) (break (lambda (c)
-                          (eq? c sep))
-                        xs)
-           (cons p (split-list (safe-cdr r) sep)))))
-
-(define (string->syms str sep)
-  (map (lambda (cs)
-         (string->symbol
-           (list->string cs)))
-       (split-list (string->list str) sep)))
-
-(define (mk-string-matcher pattern)
-  (let ((prefix (string->syms pattern #\/)))
-   (lambda (keys)
-    (begins-with prefix keys))))
-
-(define (mk-regex-matcher pattern)
-  (let ((rx (regex pattern)))
-    (lambda (keys)
-      (rx (apply string-append
-                 (intersperse "/"
-                              (map symbol->string keys)))))))
-
-(define (string-prefix? p str)
-  (and (>= (string-length str) (string-length p))
-       (string=? p (substring str 0 (string-length p)))))
-
-;; If the filter begins with 're:' then we make a regex matcher, otherwise
-;; we use a simple string matcher.
-(define (mk-single-matcher pattern)
-  (if (string-prefix? "re:" pattern)
-      (mk-regex-matcher (substring pattern 3 (string-length pattern)))
-      (mk-string-matcher pattern)))
-
-(define (mk-filter patterns)
-  (if (null? patterns)
-      ; accept everything if no patterns
-      (lambda (_) #t)
-
-      ; Otherwise accept tests that pass a pattern
-      (let ((filters (map mk-single-matcher patterns)))
-       (fold-left (lambda (fn-a fn-b)
-                    (lambda (keys)
-                      (or (fn-a keys)
-                          (fn-b keys))))
-                  (car filters)
-                  (cdr filters)))))
-
-(define (exec-help)
-  (fmt (current-error-port)
-       "Usage:" nl
-       "  run-tests help" nl
-       "  run-tests list <pattern>*" nl
-       "  run-tests run [--disable-unlink] <pattern>*" nl nl
-       (justify
-         (string-append
-           "Patterns are used to select tests.  There are two forms a pattern can take; "
-           "either a literal such as 'cache-check/bad-option', or a regular expression (prefix with 're:')."))
-       nl
-       "eg," nl
-       "    run-tests run cache-check/bad-option" nl
-       "    run-tests run re:help" nl
-       "    run-tests run cache-check thin-check re:.*missing.*file" nl
-       ))
-
-(define (exec-run args)
-  (let ((pred (mk-filter args)))
-   (if (run-scenarios (filter pred (list-scenarios)))
-       (exit)
-       (exit #f))))
-
-(define (exec-list args)
-  (let ((pred (mk-filter args)))
-   (describe-scenarios (filter pred (list-scenarios)))))
-
-;;------------------------------------------------
-;; Command line parser
-
-(define whitespace
-  (many+ (charset " \t\n")))
-
-(define (whitespace-delim ma)
-  (>> (opt whitespace)
-      (<* ma (opt whitespace))))
-
-(define (cmd-word str)
-  (whitespace-delim (lit str)))
-
-(define (switch str)
-  (whitespace-delim (>> (lit "--") (lit str))))
-
-(define not-switch
-  (whitespace-delim
-   (parse-m (<- c (neg-charset "- \t"))
-    (<- cs (many* (neg-charset " \t")))
-    (pure (list->string (cons c cs))))))
-
-(define (maybe ma)
- (alt (>> ma (pure #t))
-  (pure #f)))
-
-(define help-command-line
- (>> (cmd-word "help") (pure exec-help)))
-
-(define run-command-line
- (parse-m
-  (cmd-word "run")
-  (<- dunlink (maybe (switch "disable-unlink")))
-  (<- args (many* not-switch))
-  (pure (lambda ()
-	 (if dunlink
-	  (disable-unlink (exec-run args))
-	  (exec-run args))))))
-
-(define list-command-line
-  (parse-m
-    (cmd-word "list")
-    (<- args (many* not-switch))
-    (pure (lambda () (exec-list args)))))
-
-(define command-line-parser
- (one-of help-command-line
-         run-command-line
-         list-command-line))
-
-(define (bad-command-line)
-  (fmt (current-error-port) (dsp "bad command line\n"))
-  (exec-help)
-  (exit 1))
-
-;; (<string>) -> thunk
-(define (parse-command-line)
-  (let ((args (cdr (command-line))))
-    (receive (v st)
-             (parse command-line-parser
-                    (apply string-append
-                           (intersperse " " (cdr (command-line)))))
-             (if (success? st)
-                 v
-                 bad-command-line))))
-
-;;------------------------------------------------
-
 (register-thin-tests)
 (register-cache-tests)
 (register-era-tests)
-(register-bcache-tests)
 
-(with-dir "test-output"
- ((parse-command-line)))
+(run-tests)
 
diff --git a/functional-tests/test-runner.scm b/functional-tests/test-runner.scm
new file mode 100644
index 0000000..b21f5f9
--- /dev/null
+++ b/functional-tests/test-runner.scm
@@ -0,0 +1,182 @@
+(library
+  (test-runner)
+  (export run-tests)
+
+  (import (rnrs)
+          (only (chezscheme) load-shared-object)
+          (fmt fmt)
+          (list-utils)
+          (functional-tests)
+          (bcache bcache-tests)
+          (cache-functional-tests)
+          (era-functional-tests)
+          (parser-combinators)
+          (only (srfi s1 lists) break)
+          (regex)
+          (srfi s8 receive)
+          (temp-file)
+          (thin-functional-tests))
+
+  ;;------------------------------------------------
+
+  ;; Returns #t if the xs list matches prefix
+  (define (begins-with prefix xs)
+    (cond
+      ((null? prefix) #t)
+      ((null? xs) #f)
+      ((eq? (car prefix) (car xs))
+       (begins-with (cdr prefix) (cdr xs)))
+      (else #f)))
+
+  (define (split-list xs sep)
+    (define (safe-cdr xs)
+      (if (null? xs) '() (cdr xs)))
+
+    (if (null? xs)
+        '()
+        (receive (p r) (break (lambda (c)
+                                (eq? c sep))
+                              xs)
+                 (cons p (split-list (safe-cdr r) sep)))))
+
+  (define (string->syms str sep)
+    (map (lambda (cs)
+           (string->symbol
+             (list->string cs)))
+         (split-list (string->list str) sep)))
+
+  (define (mk-string-matcher pattern)
+    (let ((prefix (string->syms pattern #\/)))
+     (lambda (keys)
+       (begins-with prefix keys))))
+
+  (define (mk-regex-matcher pattern)
+    (let ((rx (regex pattern)))
+     (lambda (keys)
+       (rx (apply string-append
+                  (intersperse "/"
+                               (map symbol->string keys)))))))
+
+  (define (string-prefix? p str)
+    (and (>= (string-length str) (string-length p))
+         (string=? p (substring str 0 (string-length p)))))
+
+  ;; If the filter begins with 're:' then we make a regex matcher, otherwise
+  ;; we use a simple string matcher.
+  (define (mk-single-matcher pattern)
+    (if (string-prefix? "re:" pattern)
+        (mk-regex-matcher (substring pattern 3 (string-length pattern)))
+        (mk-string-matcher pattern)))
+
+  (define (mk-filter patterns)
+    (if (null? patterns)
+        ; accept everything if no patterns
+        (lambda (_) #t)
+
+        ; Otherwise accept tests that pass a pattern
+        (let ((filters (map mk-single-matcher patterns)))
+         (fold-left (lambda (fn-a fn-b)
+                      (lambda (keys)
+                        (or (fn-a keys)
+                            (fn-b keys))))
+                    (car filters)
+                    (cdr filters)))))
+
+  (define (exec-help)
+    (fmt (current-error-port)
+         "Usage:" nl
+         "  run-tests help" nl
+         "  run-tests list <pattern>*" nl
+         "  run-tests run [--disable-unlink] <pattern>*" nl nl
+         (justify
+           (string-append
+             "Patterns are used to select tests.  There are two forms a pattern can take; "
+             "either a literal such as 'cache-check/bad-option', or a regular expression (prefix with 're:')."))
+         nl
+         "eg," nl
+         "    run-tests run cache-check/bad-option" nl
+         "    run-tests run re:help" nl
+         "    run-tests run cache-check thin-check re:.*missing.*file" nl
+         ))
+
+  (define (exec-run args)
+    (let ((pred (mk-filter args)))
+     (if (run-scenarios (filter pred (list-scenarios)))
+         (exit)
+         (exit #f))))
+
+  (define (exec-list args)
+    (let ((pred (mk-filter args)))
+     (describe-scenarios (filter pred (list-scenarios)))))
+
+  ;;------------------------------------------------
+  ;; Command line parser
+
+  (define whitespace
+    (many+ (charset " \t\n")))
+
+  (define (whitespace-delim ma)
+    (>> (opt whitespace)
+        (<* ma (opt whitespace))))
+
+  (define (cmd-word str)
+    (whitespace-delim (lit str)))
+
+  (define (switch str)
+    (whitespace-delim (>> (lit "--") (lit str))))
+
+  (define not-switch
+    (whitespace-delim
+      (parse-m (<- c (neg-charset "- \t"))
+               (<- cs (many* (neg-charset " \t")))
+               (pure (list->string (cons c cs))))))
+
+  (define (maybe ma)
+    (alt (>> ma (pure #t))
+         (pure #f)))
+
+  (define help-command-line
+    (>> (cmd-word "help") (pure exec-help)))
+
+  (define run-command-line
+    (parse-m
+      (cmd-word "run")
+      (<- dunlink (maybe (switch "disable-unlink")))
+      (<- args (many* not-switch))
+      (pure (lambda ()
+              (if dunlink
+                  (disable-unlink (exec-run args))
+                  (exec-run args))))))
+
+  (define list-command-line
+    (parse-m
+      (cmd-word "list")
+      (<- args (many* not-switch))
+      (pure (lambda () (exec-list args)))))
+
+  (define command-line-parser
+    (one-of help-command-line
+            run-command-line
+            list-command-line))
+
+  (define (bad-command-line)
+    (fmt (current-error-port) (dsp "bad command line\n"))
+    (exec-help)
+    (exit 1))
+
+  ;; (<string>) -> thunk
+  (define (parse-command-line)
+    (let ((args (cdr (command-line))))
+     (receive (v st)
+              (parse command-line-parser
+                     (apply string-append
+                            (intersperse " " (cdr (command-line)))))
+              (if (success? st)
+                  v
+                  bad-command-line))))
+
+  ;;------------------------------------------------
+
+  (define (run-tests)
+    (with-dir "test-output"
+      ((parse-command-line)))))