Reraise a runtime arithmetic error as Expression.Error

CHANGELOG.md

@@ -1,5 +1,15 @@
 # Changelog
 
+## v3.0.0-rc.4
+
+### Fixed
+
+- A runtime arithmetic fault during evaluation, division by zero being the
+  canonical case, now surfaces as an `Expression.Error` instead of crashing the
+  caller. `evaluate_block!/4` and `evaluate!/4` already reraised a `RuntimeError`
+  this way (how a non-numeric operand surfaces); `ArithmeticError` was simply the
+  missing case.
+
 ## v3.0.0-rc.3
 
 ### Fixed

lib/expression.ex

@@ -169,9 +169,9 @@ defmodule Expression do
     e in Expression.Error ->
       reraise e, __STACKTRACE__
 
-    e in RuntimeError ->
+    e in [RuntimeError, ArithmeticError] ->
       reraise Expression.Error,
-              [type: :eval, message: e.message, expression: expression],
+              [type: :eval, message: Exception.message(e), expression: expression],
               __STACKTRACE__
   end
 
@@ -192,9 +192,9 @@ defmodule Expression do
     e in Expression.Error ->
       reraise e, __STACKTRACE__
 
-    e in RuntimeError ->
+    e in [RuntimeError, ArithmeticError] ->
       reraise Expression.Error,
-              [type: :eval, message: e.message, expression: expression],
+              [type: :eval, message: Exception.message(e), expression: expression],
               __STACKTRACE__
   end
 

mix.exs

@@ -1,7 +1,7 @@
 defmodule Expression.MixProject do
   use Mix.Project
 
-  @version "3.0.0-rc.3"
+  @version "3.0.0-rc.4"
 
   def project do
     [

test/expression_test.exs

@@ -190,6 +190,10 @@ defmodule ExpressionTest do
       assert_raise Expression.Error, "expression is not a number: `\"NaN\"`", fn ->
         Expression.evaluate_as_boolean!("@(\"NaN\" * 0.2 == 0.02)")
       end
+
+      assert_raise Expression.Error, "bad argument in arithmetic expression", fn ->
+        Expression.evaluate_as_boolean!("@(1 / 0 == 2)")
+      end
     end
 
     test "list with indices" do
@@ -725,6 +729,17 @@ defmodule ExpressionTest do
       end
     end
 
+    test "a division by zero returns an error tuple instead of crashing" do
+      assert {:error, %Expression.Error{message: "bad argument in arithmetic expression"}} =
+               Expression.evaluate_block("score / total", %{"score" => 10, "total" => 0})
+    end
+
+    test "a division by zero raises Expression.Error from the bang variant" do
+      assert_raise Expression.Error, "bad argument in arithmetic expression", fn ->
+        Expression.evaluate_block!("score / total", %{"score" => 10, "total" => 0})
+      end
+    end
+
     test "fixed/2 with a numeric string still formats the number" do
       assert {:ok, "4.21"} == Expression.evaluate_block("fixed(value, 2)", %{"value" => "4.209"})
     end