Raise exception on invalid argument type to .call or .call!

Closes #5

lib/interaktor/callable.rb

@@ -144,6 +144,10 @@ def success(*attributes, **options)
     #
     # @return [Interaktor::Context] the context, following interaktor execution
     def call(context = {})
+      unless context.is_a?(Hash) || context.is_a?(Interaktor::Context)
+        raise ArgumentError, "Expected a hash argument when calling the interaktor, got a #{context.class} instead."
+      end
+
       apply_default_optional_attributes(context)
       verify_attribute_presence(context)
 
@@ -161,6 +165,10 @@ def call(context = {})
     #
     # @return [Interaktor::Context] the context, following interaktor execution
     def call!(context = {})
+      unless context.is_a?(Hash) || context.is_a?(Interaktor::Context)
+        raise ArgumentError, "Expected a hash argument when calling the interaktor, got a #{context.class} instead."
+      end
+
       apply_default_optional_attributes(context)
       verify_attribute_presence(context)
 

spec/support/lint.rb

@@ -17,6 +17,12 @@
         interaktor.call(baz: "wadus")
       }.to raise_error(an_instance_of(Interaktor::Error::UnknownAttributeError).and having_attributes(attributes: [:baz]))
     end
+
+    it "fails when a non-hash or non-context argument is passed" do
+      expect {
+        interaktor.call("foo")
+      }.to raise_error(ArgumentError, /Expected a hash argument/)
+    end
   end
 
   describe ".call!" do
@@ -35,6 +41,12 @@
         interaktor.call!(baz: "wadus")
       }.to raise_error(an_instance_of(Interaktor::Error::UnknownAttributeError).and having_attributes(attributes: [:baz]))
     end
+
+    it "fails when a non-hash or non-context argument is passed" do
+      expect {
+        interaktor.call!("foo")
+      }.to raise_error(ArgumentError, /Expected a hash argument/)
+    end
   end
 
   describe "#run" do