diff --git a/utils.rkt b/utils.rkt
index 4b32736..ad2dd2c 100644
--- a/utils.rkt
+++ b/utils.rkt
@@ -86,11 +86,12 @@
          body)]))
 
 (module+ test
-  (let ([mytable #hash((a . 3) (b . 4))])
+  (test-case "auto-hash-ref/explicit"
+    (define mytable #hash((a . 3) (b . 4)))
     (check-equal? (auto-hash-ref/explicit (mytable b a)
                                           (* a b))
-                  12))
-  (let ([ht #hash((a . #t) (b . #f))])
+                  12)
+    (define ht #hash((a . #t) (b . #f)))
     (check-equal? (auto-hash-ref/explicit (ht a b)
                                           (and (not a) b))
                   #f)))
@@ -118,13 +119,14 @@
            body))]))
 
 (module+ test
-  (let ([ht #hash((x . #t) (y . #t) (t . #f))]
-        [z #t])
-    (check-equal? (auto-hash-ref/: ht
+  (test-case "auto-hash-ref/:"
+    (define ht1 #hash((x . #t) (y . #t) (t . #f)))
+    (define z #t)
+    (check-equal? (auto-hash-ref/: ht1
                                    (and :x (not :y) z (or (and :t) :x)))
-                  #f))
-  (let ([ht #hash((a . 1) (b . 2))])
-    (check-equal? (auto-hash-ref/: ht (+ :a (* 2 :b)))
+                  #f)
+    (define ht2 #hash((a . 1) (b . 2)))
+    (check-equal? (auto-hash-ref/: ht2 (+ :a (* 2 :b)))
                   5)))
 
 ;;; The helper functions for auto-hash-ref/:.
@@ -173,9 +175,10 @@
     (eval expr)))
 
 (module+ test
-  (check-equal? (let ([ht #hash((a . 1) (b . 1))])
-                  (eval-with ht '(+ b a 1)))
-                3))
+  (test-case "eval-with"
+    (check-equal? (let ([ht #hash((a . 1) (b . 1))])
+                    (eval-with ht '(+ b a 1)))
+                  3)))
 
 ;;; Same as eval-with, but returns only the first value produced by
 ;;; the evaluated expression.
@@ -199,8 +202,9 @@
     [else '()]))
 
 (module+ test
-  (check-equal? (extract-symbols '(1 (2 3) x (y z 3)))
-                '(x y z)))
+  (test-case "extract-symbols"
+    (check-equal? (extract-symbols '(1 (2 3) x (y z 3)))
+                  '(x y z))))
 
 
 ;;; =========================
@@ -221,9 +225,10 @@
   (with-output-to-string (λ () (display x))))
 
 (module+ test
-  (check-equal? (any->string 'a) "a")
-  (check-equal? (any->string '(a 1 (x y))) "(a 1 (x y))")
-  (check-equal? (any->string "hello") "hello"))
+  (test-case "any->string"
+   (check-equal? (any->string 'a) "a")
+   (check-equal? (any->string '(a 1 (x y))) "(a 1 (x y))")
+   (check-equal? (any->string "hello") "hello")))
 
 ;;; A string variable mapping is a mapping from variables to strings.
 (define (string-variable-mapping? dict) (hash/c symbol? string?))
@@ -233,7 +238,8 @@
   (for/hash ([(key val) ht]) (values key (any->string val))))
 
 (module+ test
-  (let ([mp (stringify-variable-mapping #hash((a . (and a b)) (b . (not b))))])
+  (test-case "stringify-variable-mapping"
+    (define mp (stringify-variable-mapping #hash((a . (and a b)) (b . (not b)))))
     (check-equal? (hash-ref mp 'a) "(and a b)")
     (check-equal? (hash-ref mp 'b) "(not b)")))
 
@@ -242,8 +248,9 @@
   (with-input-from-string str (λ () (read))))
 
 (module+ test
-  (check-equal? (string->any "(or b (not a))") '(or b (not a)))
-  (check-equal? (string->any "14") 14))
+  (test-case "string->any"
+    (check-equal? (string->any "(or b (not a))") '(or b (not a)))
+    (check-equal? (string->any "14") 14)))
 
 ;;; Given a sexp, converts all "#f" to #f and "#t" to #t.
 ;;;
@@ -270,7 +277,8 @@
     [datum (func datum)]))
 
 (module+ test
-  (check-equal? (map-sexp add1 '(1 2 (4 10) 3)) '(2 3 (5 11) 4)))
+  (test-case "map-sexp"
+    (check-equal? (map-sexp add1 '(1 2 (4 10) 3)) '(2 3 (5 11) 4))))
 
 ;;; Reads a sexp from a string produced by Org-mode for a named table.
 ;;; See example.org for examples.
@@ -284,10 +292,11 @@
 (define unorg read-org-sexp)
 
 (module+ test
-  (check-equal? (read-org-sexp "((\"a\" \"(and a b)\") (\"b\" \"(or b (not a))\"))")
-                '((a (and a b)) (b (or b (not a)))))
-  (check-equal? (read-org-sexp "(#t \"#t\" \"#t \" '(1 2 \"#f\"))")
-                '(#t #t #t '(1 2 #f))))
+  (test-case "read-org-sexp"
+    (check-equal? (read-org-sexp "((\"a\" \"(and a b)\") (\"b\" \"(or b (not a))\"))")
+                  '((a (and a b)) (b (or b (not a)))))
+    (check-equal? (read-org-sexp "(#t \"#t\" \"#t \" '(1 2 \"#f\"))")
+                  '(#t #t #t '(1 2 #f)))))
 
 ;;; A contract allowing pairs constructed via cons or via list.
 (define (general-pair/c key-contract val-contract)
@@ -311,10 +320,11 @@
                                       val))])))
 
 (module+ test
-  (check-equal? (unstringify-pairs '(("a" . "1") ("b" . "(and a (not b))")))
-                '((a . 1) (b . (and a (not b)))))
-  (check-equal? (unstringify-pairs '(("a" . 1) ("b" . "(and a (not b))")))
-                '((a . 1) (b . (and a (not b))))))
+  (test-case "unstringify-pairs"
+    (check-equal? (unstringify-pairs '(("a" . "1") ("b" . "(and a (not b))")))
+                  '((a . 1) (b . (and a (not b)))))
+    (check-equal? (unstringify-pairs '(("a" . 1) ("b" . "(and a (not b))")))
+                  '((a . 1) (b . (and a (not b)))))))
 
 ;;; Reads a variable mapping from a string, such as the one which
 ;;; Org-mode produces from tables.
@@ -322,9 +332,10 @@
   (compose make-immutable-hash unstringify-pairs string->any))
 
 (module+ test
-  (let ([m1 (read-org-variable-mapping "((\"a\" \"(and a b)\") (\"b\" \"(or b (not a))\"))")]
-        [m2 (read-org-variable-mapping "((\"a\" . \"(and a b)\") (\"b\" . \"(or b (not a))\"))")]
-        [m3 (unorgv "((\"a\" . \"(and a b)\") (\"b\" . \"(or b (not a))\"))")])
+  (test-case "read-org-variable-mapping"
+    (define m1 (read-org-variable-mapping "((\"a\" \"(and a b)\") (\"b\" \"(or b (not a))\"))"))
+    (define m2 (read-org-variable-mapping "((\"a\" . \"(and a b)\") (\"b\" . \"(or b (not a))\"))"))
+    (define m3 (unorgv "((\"a\" . \"(and a b)\") (\"b\" . \"(or b (not a))\"))"))
     (check-equal? (hash-ref m1 'a) '(and a b))
     (check-equal? (hash-ref m2 'a) '(and a b))
     (check-equal? (hash-ref m3 'a) '(and a b))
@@ -343,7 +354,8 @@
   (string->any (string-append "(" str ")")))
 
 (module+ test
-  (check-equal? (read-symbol-list "a b c") '(a b c)))
+  (test-case "read-symbol-list"
+    (check-equal? (read-symbol-list "a b c") '(a b c))))
 
 ;;; Removes the first and the last symbol of a given string.
 ;;;
@@ -353,7 +365,8 @@
   (substring str 1 (- (string-length str) 1)))
 
 (module+ test
-  (check-equal? (drop-first-last "(a b)") "a b"))
+  (test-case "drop-first-last"
+    (check-equal? (drop-first-last "(a b)") "a b")))
 
 ;;; Converts a list of sets of symbols to a list of strings containing
 ;;; those symbols.
@@ -361,8 +374,9 @@
   (map (compose drop-first-last any->string set->list) lst))
 
 (module+ test
-  (check-equal? (list-sets->list-strings (list (set 'x 'y) (set 'z) (set) (set 't)))
-                '("y x" "z" "" "t")))
+  (test-case "list-sets->list-strings"
+    (check-equal? (list-sets->list-strings (list (set 'x 'y) (set 'z) (set) (set 't)))
+                  '("y x" "z" "" "t"))))
 
 ;;; Pretty-prints a set of sets of symbols.
 ;;;
@@ -372,7 +386,8 @@
   (string-join (for/list ([m ms]) (format "{~a}" (pretty-print-set m))) ""))
 
 (module+ test
-  (check-equal? (pretty-print-set-sets (set (set 'a 'b) (set 'c))) "{a b}{c}"))
+  (test-case "pretty-print-set-sets"
+    (check-equal? (pretty-print-set-sets (set (set 'a 'b) (set 'c))) "{a b}{c}")))
 
 
 ;;; ==========================
@@ -394,12 +409,14 @@
        (list (func u) (func v))))))
 
 (module+ test
-  (let* ([gr1 (directed-graph '((a b) (b c)))]
-         [gr2 (undirected-graph '((a b) (b c)))]
-         [dbl (λ (x) (let ([x-str (symbol->string x)])
-                       (string->symbol (string-append x-str x-str))))]
-         [new-gr1 (update-vertices/unweighted gr1 dbl)]
-         [new-gr2 (update-vertices/unweighted gr2 dbl)])
+  (test-case "update-vertices/unweighted"
+    (define gr1 (directed-graph '((a b) (b c))))
+    (define gr2 (undirected-graph '((a b) (b c))))
+    (define dbl (λ (x) (let ([x-str (symbol->string x)])
+                         (string->symbol (string-append x-str x-str)))))
+    (define new-gr1 (update-vertices/unweighted gr1 dbl))
+    (define new-gr2 (update-vertices/unweighted gr2 dbl))
+
     (check-false (has-vertex? new-gr1 'a))
     (check-true (has-vertex? new-gr1 'aa))
     (check-false (has-vertex? new-gr1 'b))
@@ -436,14 +453,16 @@
      (weighted-graph/directed edges)]))
 
 (module+ test
-  (let* ([gr1 (directed-graph '((a b) (b c)))]
-         [gr2 (undirected-graph '((a b) (b c)))]
-         [dbl (λ (x) (let ([x-str (symbol->string x)])
-                       (string->symbol (string-append x-str x-str))))]
-         [new-gr1-ug (update-graph gr1 #:v-func dbl)]
-         [new-gr2-ug (update-graph gr2 #:v-func dbl)]
-         [gr3 (weighted-graph/directed '((10 a b) (11 b c)))]
-         [new-gr3 (update-graph gr3 #:v-func dbl #:e-func (λ (x) (* 2 x)))])
+  (test-case "update-graph"
+    (define gr1 (directed-graph '((a b) (b c))))
+    (define gr2 (undirected-graph '((a b) (b c))))
+    (define dbl (λ (x) (let ([x-str (symbol->string x)])
+                         (string->symbol (string-append x-str x-str)))))
+    (define new-gr1-ug (update-graph gr1 #:v-func dbl))
+    (define new-gr2-ug (update-graph gr2 #:v-func dbl))
+    (define gr3 (weighted-graph/directed '((10 a b) (11 b c))))
+    (define new-gr3 (update-graph gr3 #:v-func dbl #:e-func (λ (x) (* 2 x))))
+
     (check-false (has-vertex? new-gr1-ug 'a))
     (check-true (has-vertex? new-gr1-ug 'aa))
     (check-false (has-vertex? new-gr1-ug 'b))
@@ -475,7 +494,8 @@
   (string-join (sort (set-map s any->string) string<?)))
 
 (module+ test
-  (check-equal? (pretty-print-set (set 'a 'b 1)) "1 a b"))
+  (test-case "pretty-print-set"
+    (check-equal? (pretty-print-set (set 'a 'b 1)) "1 a b")))
 
 
 ;;; =========================
@@ -495,8 +515,9 @@
     (hash-update ht e (λ (ls) (cons l ls)) empty)))
 
 (module+ test
-  (let-values ([(e1 l1) (collect-by-key '((1 2) (1 3)) '(a b))]
-               [(e2 l2) (collect-by-key '((1 2) (1 2)) '(a b))])
+  (test-case "collect-by-key"
+    (define-values (e1 l1) (collect-by-key '((1 2) (1 3)) '(a b)))
+    (define-values (e2 l2) (collect-by-key '((1 2) (1 2)) '(a b)))
     (check-equal? e1 '((1 2) (1 3))) (check-equal? l1 '((a) (b)))
     (check-equal? e2 '((1 2))) (check-equal? l2 '((b a)))))
 
@@ -506,7 +527,8 @@
     (values es (map list->set ls))))
 
 (module+ test
-  (let-values ([(e3 l3) (collect-by-key/sets '(a b a) '(1 2 1))])
+  (test-case "collect-by-key/sets"
+    (define-values (e3 l3) (collect-by-key/sets '(a b a) '(1 2 1)))
     (check-equal? e3 '(a b)) (check-equal? l3 (list (set 1) (set 2)))))
 
 ;;; Converts the values of a hash table from lists to sets.
@@ -515,16 +537,18 @@
     (values k (list->set v))))
 
 (module+ test
-  (check-equal? (ht-values/list->set #hash((a . (1 1))))
-                (hash 'a (set 1))))
+  (test-case "ht-values/list->set"
+    (check-equal? (ht-values/list->set #hash((a . (1 1))))
+                  (hash 'a (set 1)))))
 
 ;;; Returns the key-value pairs of a given hash table in the order in
 ;;; which the hash table orders them for hash-map and hash-for-each.
 (define (hash->list/ordered ht) (hash-map ht cons #t))
 
 (module+ test
-  (check-equal? (hash->list/ordered #hash((b . 1) (a . 1)))
-                '((a . 1) (b . 1))))
+  (test-case "hash->list/ordered"
+    (check-equal? (hash->list/ordered #hash((b . 1) (a . 1)))
+                  '((a . 1) (b . 1)))))
 
 ;;; Given a list of lists, splits every single list at the given
 ;;; position, and then returns two lists: one consisting of the first
@@ -538,7 +562,8 @@
     [(cons lefts rights) (values lefts rights)]))
 
 (module+ test
-  (let-values ([(l1 l2) (multi-split-at '((1 2 3) (a b c)) 2)])
+  (test-case "multi-split-at"
+    (define-values (l1 l2) (multi-split-at '((1 2 3) (a b c)) 2))
     (check-equal? l1 '((1 2) (a b))) (check-equal? l2 '((3) (c)))))
 
 ;;; Given a list of lists of the same length, transposes them.
@@ -554,7 +579,8 @@
            ((curry apply) in-parallel)))
 
 (module+ test
-  (check-equal? (lists-transpose '((1 2) (a b))) '((1 a) (2 b))))
+  (test-case "lists-transpose"
+    (check-equal? (lists-transpose '((1 2) (a b))) '((1 a) (2 b)))))
 
 
 ;;; =========
@@ -568,8 +594,9 @@
     [(arity-at-least _) #f] [arity #t]))
 
 (module+ test
-  (check-true (procedure-fixed-arity? not))
-  (check-false (procedure-fixed-arity? +)))
+  (test-case "procedure-fixed-arity?"
+    (check-true (procedure-fixed-arity? not))
+    (check-false (procedure-fixed-arity? +))))
 
 
 ;;; ==========
@@ -597,21 +624,22 @@
     [(min max) (for/stream ([i (in-naturals)]) (random min max))]))
 
 (module+ test
-  (check-equal? (stream->list (stream-take (in-random 100) 10))
-                '(85 65 20 40 89 45 54 38 26 62))
-  (check-equal? (stream->list (stream-take (in-random 50 100) 10))
-                '(75 59 82 85 61 85 59 64 75 53))
-  (check-equal? (stream->list (stream-take (in-random) 10))
-                '(0.1656109603231493
-                  0.9680391127132195
-                  0.051518813640790355
-                  0.755901955353936
-                  0.5923534604277275
-                  0.5513340634474264
-                  0.7022057040731392
-                  0.48375400938578744
-                  0.7538961707172924
-                  0.01828428516237329)))
+  (test-case "in-random"
+    (check-equal? (stream->list (stream-take (in-random 100) 10))
+                  '(85 65 20 40 89 45 54 38 26 62))
+    (check-equal? (stream->list (stream-take (in-random 50 100) 10))
+                  '(75 59 82 85 61 85 59 64 75 53))
+    (check-equal? (stream->list (stream-take (in-random) 10))
+                  '(0.1656109603231493
+                    0.9680391127132195
+                    0.051518813640790355
+                    0.755901955353936
+                    0.5923534604277275
+                    0.5513340634474264
+                    0.7022057040731392
+                    0.48375400938578744
+                    0.7538961707172924
+                    0.01828428516237329))))
 
 
 ;;; ===========================
@@ -634,16 +662,17 @@
   (foldr cp-2 (sequence->stream (in-value (list))) ss))
 
 (module+ test
-  (check-equal? (stream->list (cartesian-product/stream (in-range 3) (in-range 4 6) '(a b)))
-                '((0 4 a)
-                  (0 4 b)
-                  (0 5 a)
-                  (0 5 b)
-                  (1 4 a)
-                  (1 4 b)
-                  (1 5 a)
-                  (1 5 b)
-                  (2 4 a)
-                  (2 4 b)
-                  (2 5 a)
-                  (2 5 b))))
+  (test-case "cartesian-product/stream"
+    (check-equal? (stream->list (cartesian-product/stream (in-range 3) (in-range 4 6) '(a b)))
+                  '((0 4 a)
+                    (0 4 b)
+                    (0 5 a)
+                    (0 5 b)
+                    (1 4 a)
+                    (1 4 b)
+                    (1 5 a)
+                    (1 5 b)
+                    (2 4 a)
+                    (2 4 b)
+                    (2 5 a)
+                    (2 5 b)))))