Re-instate Robby's hack to display test results off REPL errors.

... and generalize it so there's an action before (clearing the old
tests out) in addition to after (displaying the test results).

Also, do for DMdA as for HtDP.

collects/deinprogramm/deinprogramm-langs.rkt

@@ -767,12 +767,27 @@
                                      (drscheme:rep:current-rep)
 				     '#%deinprogramm))
 
-	  ;; DeinProgramm addition: needed for test boxes; see the code
-	  ;; in collects/drscheme/private/language.ss
           (define/override (front-end/interaction port settings)
-	    (let ((reader (get-reader)))
+            (let ([reader (get-reader)] ;; DeinProgramm addition:
-	      (lambda ()
+					;; needed for test boxes; see
-		(reader (object-name port) port))))
+					;; the code in
+					;; collects/drscheme/private/language.ss
+		  [start? #t]
+                  [done? #f])
+              (λ ()
+                (cond
+		  [start?
+		   (set! start? #f)
+		   #'(reset-tests)]
+                  [done? eof]
+                  [else
+                   (let ([ans (reader (object-name port) port)])
+                     (cond
+                       [(eof-object? ans)
+                        (set! done? #t)
+                        #`(test)]
+                       [else
+                        ans]))]))))
 
           (define/augment (capability-value key)
             (case key

collects/lang/htdp-langs.rkt

@@ -19,6 +19,7 @@
          compiler/embed
          wxme/wxme
          setup/dirs
+         test-engine/racket-tests
          
          ;; this module is shared between the drscheme's namespace (so loaded here) 
          ;; and the user's namespace in the teaching languages
@@ -554,6 +555,26 @@
                                      (htdp-lang-settings-teachpacks settings)
                                      (drscheme:rep:current-rep)))
           
+          (define/override (front-end/interaction port settings)
+            (let ([t (super front-end/interaction port settings)]
+		  [start? #t]
+                  [done? #f])
+              (λ ()
+                (cond
+		  [start?
+		   (set! start? #f)
+		   #'(reset-tests)]
+                  [done? eof]
+                  [else
+                   (let ([ans (t)])
+                     (cond
+                       [(eof-object? ans)
+                        (set! done? #t)
+                        #`(test)]
+                       [else
+                        ans]))]))))
+
+
           (define keywords #f)
           (define/augment (capability-value key)
             (case key

collects/test-engine/racket-tests.rkt

@@ -110,12 +110,9 @@
                      skipto/cdr skipto/third ;; application of insert-test
                      '(syntax-e cdr cdr syntax-e car) ;; lambda
                      )))
-      #`(begin
+      #`(let ([test-engine (namespace-variable-value
-          (let ([test-engine (namespace-variable-value
                             'test~object #f builder (current-namespace))])
 	  (when test-engine
-              (begin
-                (send test-engine reset-info)
 	    (insert-test test-engine
 			 (lambda ()
 			   #,(with-stepper-syntax-properties
@@ -137,8 +134,7 @@
 				 #,(with-stepper-syntax-properties
 				    (['stepper-no-lifting-info #t]
 				     ['stepper-hide-reduction #t])
-                                        #'test-engine)))))))))
+				    #'test-engine))))))))))
-          (test))))
 
 (define-for-syntax (check-context?)
   (let ([c (syntax-local-context)])
@@ -302,6 +298,12 @@
           [else
            #t])))
 
+(define (reset-tests)
+  (let ([test-engine (namespace-variable-value
+		      'test~object #f builder (current-namespace))])
+    (when test-engine
+      (send test-engine reset-info))))
+
 (define (builder)
   (let ([te (build-test-engine)])
     (namespace-set-variable-value! 'test~object te (current-namespace))
@@ -348,7 +350,7 @@
       #'(display-results*)
       'test-call #t)]))
 
-(provide run-tests display-results test builder)
+(provide run-tests display-results test builder reset-tests)
 
 (define (build-test-engine)
   (let ([engine (make-object scheme-test%)])