GraphQL TimeType to throw GraphQL::CoercionErrors

app/graphql/types/time_type.rb

@@ -7,6 +7,8 @@ module Types
 
     def self.coerce_input(value, ctx)
       Time.parse(value)
+    rescue ArgumentError, TypeError => e
+      raise GraphQL::CoercionError, e.message
     end
 
     def self.coerce_result(value, ctx)

spec/graphql/types/time_type_spec.rb

@@ -15,4 +15,14 @@ RSpec.describe GitlabSchema.types['Time'] do
   it 'coerces an ISO-time into Time object' do
     expect(described_class.coerce_isolated_input(iso)).to eq(time)
   end
+
+  it 'rejects invalid input' do
+    expect { described_class.coerce_isolated_input('not valid') }
+      .to raise_error(GraphQL::CoercionError)
+  end
+
+  it 'rejects nil' do
+    expect { described_class.coerce_isolated_input(nil) }
+      .to raise_error(GraphQL::CoercionError)
+  end
 end

spec/requests/api/graphql/mutations/issues/set_due_date_spec.rb

@@ -49,13 +49,13 @@ RSpec.describe 'Setting Due Date of an issue' do
     expect(mutation_response['issue']['dueDate']).to eq(2.days.since.to_date.to_s)
   end
 
-  context 'when passing due date without a date value' do
+  context 'when the due date value is not a valid time' do
     let(:input) { { due_date: 'test' } }
 
-    it 'returns internal server error' do
+    it 'returns a coercion error' do
       post_graphql_mutation(mutation, current_user: current_user)
 
-      expect(graphql_errors).to include(a_hash_including('message' => 'Internal server error'))
+      expect(graphql_errors).to include(a_hash_including('message' => /provided invalid value for dueDate/))
     end
   end
 end