Improve KeyError message for Context#[]

z64 · Apr 18, 2018 · ab37990 · ab37990
1 parent 45d0ee9
commit ab37990
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Showing 2 changed files with 6 additions and 2 deletions.
diff --git a/spec/context_spec.cr b/spec/context_spec.cr
@@ -16,7 +16,7 @@ describe Discord::Context do
 
   it "raises on a type that hasn't been stored" do
     context = Discord::Context.new
-    expect_raises(Exception) do
+    expect_raises(KeyError, "Missing reference in context to Storage") do
       context[Storage]
     end
   end

diff --git a/src/discordcr-middleware/context.cr b/src/discordcr-middleware/context.cr
@@ -28,7 +28,11 @@ module Discord
 
     # Access a stored value by class
     def [](clazz : T.class) : T forall T
-      @extensions[clazz.crystal_type_id].unsafe_as(T)
+      if reference = @extensions[clazz.crystal_type_id]?
+        reference.unsafe_as(T)
+      else
+        raise KeyError.new("Missing reference in context to #{T}")
+      end
     end
 
     # Store an object in this class. The object must be a `class`.