Add mutation toggling WIP state of merge requests

This is mainly the setup of mutations for GraphQL. Including
authorization and basic return type-structure.

4 files changed, 79 insertions, 2 deletions

diff --git a/spec/graphql/gitlab_schema_spec.rb b/spec/graphql/gitlab_schema_spec.rb
index 515bbe78cb7..b9ddb427e85 100644
--- a/spec/graphql/gitlab_schema_spec.rb
+++ b/spec/graphql/gitlab_schema_spec.rb
@@ -18,8 +18,6 @@ describe GitlabSchema do
   end
 
   it 'has the base mutation' do
-    pending('Adding an empty mutation breaks the documentation explorer')
-
     expect(described_class.mutation).to eq(::Types::MutationType.to_graphql)
   end
 
diff --git a/spec/graphql/mutations/concerns/mutations/resolves_project_spec.rb b/spec/graphql/mutations/concerns/mutations/resolves_project_spec.rb
new file mode 100644
index 00000000000..19f5a8907a2
--- /dev/null
+++ b/spec/graphql/mutations/concerns/mutations/resolves_project_spec.rb
@@ -0,0 +1,19 @@
+require 'spec_helper'
+
+describe Mutations::ResolvesProject do
+  let(:mutation_class) do
+    Class.new(Mutations::BaseMutation) do
+      include Mutations::ResolvesProject
+    end
+  end
+
+  let(:context) { double }
+  subject(:mutation) { mutation_class.new(object: nil, context: context) }
+
+  it 'uses the ProjectsResolver to resolve projects by path' do
+    project = create(:project)
+
+    expect(Resolvers::ProjectResolver).to receive(:new).with(object: nil, context: context).and_call_original
+    expect(mutation.resolve_project(full_path: project.full_path)).to eq(project)
+  end
+end
diff --git a/spec/graphql/mutations/merge_requests/set_wip_spec.rb b/spec/graphql/mutations/merge_requests/set_wip_spec.rb
new file mode 100644
index 00000000000..e600abf3941
--- /dev/null
+++ b/spec/graphql/mutations/merge_requests/set_wip_spec.rb
@@ -0,0 +1,51 @@
+require 'spec_helper'
+
+describe Mutations::MergeRequests::SetWip do
+  let(:merge_request) { create(:merge_request) }
+  let(:user) { create(:user) }
+  subject(:mutation) { described_class.new(object: nil, context: { current_user: user }) }
+
+  describe '#resolve' do
+    let(:wip) { true }
+    let(:mutated_merge_request) { subject[:merge_request] }
+    subject { mutation.resolve(project_path: merge_request.project.full_path, iid: merge_request.iid, wip: wip) }
+
+    it 'raises an error if the resource is not accessible to the user' do
+      expect { subject }.to raise_error(Gitlab::Graphql::Errors::ResourceNotAvailable)
+    end
+
+    context 'when the user can update the merge request' do
+      before do
+        merge_request.project.add_developer(user)
+      end
+
+      it 'returns the merge request as a wip' do
+        expect(mutated_merge_request).to eq(merge_request)
+        expect(mutated_merge_request).to be_work_in_progress
+        expect(subject[:errors]).to be_empty
+      end
+
+      it 'returns errors merge request could not be updated' do
+        # Make the merge request invalid
+        merge_request.allow_broken = true
+        merge_request.update!(source_project: nil)
+
+        expect(subject[:errors]).not_to be_empty
+      end
+
+      context 'when passing wip as false' do
+        let(:wip) { false }
+
+        it 'removes `wip` from the title' do
+          merge_request.update(title: "WIP: working on it")
+
+          expect(mutated_merge_request).not_to be_work_in_progress
+        end
+
+        it 'does not do anything if the title did not start with wip' do
+          expect(mutated_merge_request).not_to be_work_in_progress
+        end
+      end
+    end
+  end
+end
diff --git a/spec/graphql/types/mutation_type_spec.rb b/spec/graphql/types/mutation_type_spec.rb
new file mode 100644
index 00000000000..a67d83b1edf
--- /dev/null
+++ b/spec/graphql/types/mutation_type_spec.rb
@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Types::MutationType do
+  it 'is expected to have the MergeRequestSetWip' do
+    expect(described_class).to have_graphql_mutation(Mutations::MergeRequests::SetWip)
+  end
+end