improve error message when last arg to flow is a vector

nubank · Jun 8, 2020 · 421e22a · 421e22a
1 parent 3df23c7
commit 421e22a
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Showing 2 changed files with 18 additions and 6 deletions.
diff --git a/src/state_flow/core.clj b/src/state_flow/core.clj
@@ -91,6 +91,8 @@
   [{:keys [description caller-meta]} & flows]
   (when-not (string-expr? description)
     (throw (IllegalArgumentException. "The first argument to flow must be a description string")))
+  (when (vector? (last flows))
+    (throw (ex-info "The last argument to flow must be a flow/step, not a binding vector." {})))
   (let [flow-meta caller-meta
         flows'    (or flows `[(m/return nil)])]
     `(m/do-let

diff --git a/test/state_flow/core_test.clj b/test/state_flow/core_test.clj
@@ -29,6 +29,21 @@
 (def empty-flow
   (flow "empty"))
 
+(deftest test-flow
+  (testing "flow without description fails at macro-expansion time"
+    (is (re-find #"first argument .* must be .* description string"
+                 (try
+                   (macroexpand `(flow (state/return {})))
+                   (catch clojure.lang.Compiler$CompilerException e
+                     (.. e getCause getMessage))))))
+
+  (testing "flow with vector as last argument fails at macro-expansion time"
+    (is (re-find #"last argument .* must be a flow/step"
+                 (try
+                   (macroexpand `(flow "" [x (state/get-state)]))
+                   (catch clojure.lang.Compiler$CompilerException e
+                     (.. e getCause getMessage)))))))
+
 (deftest run-flow
   (testing "default initial state is an empty map"
     (is (= {}
@@ -49,12 +64,7 @@
   (testing "empty flow runs without exception"
     (is (nil? (first (state-flow/run empty-flow {})))))
 
-  (testing "flow without description fails at macro-expansion time"
-    (is (re-find #"first argument .* must be .* description string"
-                 (try
-                   (macroexpand `(flow (state/return {})))
-                   (catch clojure.lang.Compiler$CompilerException e
-                     (.. e getCause getMessage))))))
+
 
   (testing "flow with a `(str ..)` expr for the description is fine"
     (is (macroexpand `(flow (str "foo") [original (state/gets :value)