Check for recursion and fail if too recursive

- List all overly-recursive fields
- Reduce recursion threshold to 2
- Add test for not-recursive-enough query
- Use reusable methods in tests
- Add changelog
- Set changeable acceptable recursion level
- Add error check test helpers

5 files changed, 176 insertions, 7 deletions

diff --git a/spec/fixtures/api/graphql/recursive-introspection.graphql b/spec/fixtures/api/graphql/recursive-introspection.graphql
new file mode 100644
index 00000000000..db970bb14b6
--- /dev/null
+++ b/spec/fixtures/api/graphql/recursive-introspection.graphql
@@ -0,0 +1,57 @@
+query allSchemaTypes {
+  __schema {
+    types {
+      fields {
+        type{
+          fields {
+            type {
+              fields {
+                type {
+                  fields {
+                    type {
+                      fields {
+                        type {
+                          fields {
+                            type {
+                              fields {
+                                type {
+                                  fields {
+                                    type {
+                                      fields {
+                                        type {
+                                          fields {
+                                            type {
+                                              fields {
+                                                type {
+                                                  fields {
+                                                    type {
+                                                      fields {
+                                                        name
+                                                      }
+                                                    }
+                                                  }
+                                                }
+                                              }
+                                            }
+                                          }
+                                        }
+                                      }
+                                    }
+                                  }
+                                }
+                              }
+                            }
+                          }
+                        }
+                      }
+                    }
+                  }
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+}
\ No newline at end of file
diff --git a/spec/fixtures/api/graphql/recursive-query.graphql b/spec/fixtures/api/graphql/recursive-query.graphql
new file mode 100644
index 00000000000..d1616c4de6e
--- /dev/null
+++ b/spec/fixtures/api/graphql/recursive-query.graphql
@@ -0,0 +1,47 @@
+{
+  project(fullPath: "gitlab-org/gitlab-ce") {
+    group {
+      projects {
+        edges {
+          node {
+            group {
+              projects {
+                edges {
+                  node {
+                    group {
+                      projects {
+                        edges {
+                          node {
+                            group {
+                              projects {
+                                edges {
+                                  node {
+                                    group {
+                                      projects {
+                                        edges {
+                                          node {
+                                            group {
+                                              description
+                                            }
+                                          }
+                                        }
+                                      }
+                                    }
+                                  }
+                                }
+                              }
+                            }
+                          }
+                        }
+                      }
+                    }
+                  }
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+}
diff --git a/spec/fixtures/api/graphql/small-recursive-introspection.graphql b/spec/fixtures/api/graphql/small-recursive-introspection.graphql
new file mode 100644
index 00000000000..1025043b474
--- /dev/null
+++ b/spec/fixtures/api/graphql/small-recursive-introspection.graphql
@@ -0,0 +1,15 @@
+query allSchemaTypes {
+  __schema {
+    types {
+      fields {
+        type {
+          fields {
+            type {
+              name
+            }
+          }
+        }
+      }
+    }
+  }
+}
diff --git a/spec/requests/api/graphql/gitlab_schema_spec.rb b/spec/requests/api/graphql/gitlab_schema_spec.rb
index e1eb7c7f738..1f2bc67a9d2 100644
--- a/spec/requests/api/graphql/gitlab_schema_spec.rb
+++ b/spec/requests/api/graphql/gitlab_schema_spec.rb
@@ -13,7 +13,7 @@ describe 'GitlabSchema configurations' do
 
           subject
 
-          expect(graphql_errors.flatten.first['message']).to include('which exceeds max complexity of 1')
+          expect_graphql_errors_to_include /which exceeds max complexity of 1/
         end
       end
     end
@@ -21,12 +21,11 @@ describe 'GitlabSchema configurations' do
     describe '#max_depth' do
       context 'when query depth is too high' do
         it 'shows error' do
-          errors = { "message" => "Query has depth of 2, which exceeds max depth of 1" }
           allow(GitlabSchema).to receive(:max_query_depth).and_return 1
 
           subject
 
-          expect(graphql_errors.flatten).to include(errors)
+          expect_graphql_errors_to_include /exceeds max depth/
         end
       end
 
@@ -36,7 +35,41 @@ describe 'GitlabSchema configurations' do
 
           subject
 
-          expect(Array.wrap(graphql_errors).compact).to be_empty
+          expect_graphql_errors_to_be_empty
+        end
+      end
+    end
+  end
+
+  context 'depth, complexity and recursion checking' do
+    context 'unauthenticated recursive queries' do
+      context 'a not-quite-recursive-enough introspective query' do
+        it 'succeeds' do
+          query = File.read(Rails.root.join('spec/fixtures/api/graphql/small-recursive-introspection.graphql'))
+
+          post_graphql(query, current_user: nil)
+
+          expect_graphql_errors_to_be_empty
+        end
+      end
+
+      context 'a deep but simple recursive introspective query' do
+        it 'fails due to recursion' do
+          query = File.read(Rails.root.join('spec/fixtures/api/graphql/recursive-introspection.graphql'))
+
+          post_graphql(query, current_user: nil)
+
+          expect_graphql_errors_to_include [/Recursive query/]
+        end
+      end
+
+      context 'a deep recursive non-introspective query' do
+        it 'fails due to recursion, complexity and depth' do
+          query = File.read(Rails.root.join('spec/fixtures/api/graphql/recursive-query.graphql'))
+
+          post_graphql(query, current_user: nil)
+
+          expect_graphql_errors_to_include [/Recursive query/, /exceeds max complexity/, /exceeds max depth/]
         end
       end
     end
@@ -86,7 +119,7 @@ describe 'GitlabSchema configurations' do
         # Expect errors for each query
         expect(graphql_errors.size).to eq(3)
         graphql_errors.each do |single_query_errors|
-          expect(single_query_errors.first['message']).to include('which exceeds max complexity of 4')
+          expect_graphql_errors_to_include(/which exceeds max complexity of 4/)
         end
       end
     end
@@ -103,12 +136,12 @@ describe 'GitlabSchema configurations' do
   end
 
   context 'when IntrospectionQuery' do
-    it 'is not too complex' do
+    it 'is not too complex nor recursive' do
       query = File.read(Rails.root.join('spec/fixtures/api/graphql/introspection.graphql'))
 
       post_graphql(query, current_user: nil)
 
-      expect(graphql_errors).to be_nil
+      expect_graphql_errors_to_be_empty
     end
   end
 
diff --git a/spec/support/helpers/graphql_helpers.rb b/spec/support/helpers/graphql_helpers.rb
index 4d2ad165fd6..69bf1f0f3fa 100644
--- a/spec/support/helpers/graphql_helpers.rb
+++ b/spec/support/helpers/graphql_helpers.rb
@@ -213,6 +213,23 @@ module GraphqlHelpers
     end
   end
 
+  def expect_graphql_errors_to_include(regexes_to_match)
+    raise "No errors. Was expecting to match #{regexes_to_match}" if graphql_errors.nil? || graphql_errors.empty?
+
+    error_messages = flattened_errors.collect { |error_hash| error_hash["message"] }
+    Array.wrap(regexes_to_match).flatten.each do |regex|
+      expect(error_messages).to include a_string_matching regex
+    end
+  end
+
+  def expect_graphql_errors_to_be_empty
+    expect(flattened_errors).to be_empty
+  end
+
+  def flattened_errors
+    Array.wrap(graphql_errors).flatten.compact
+  end
+
   # Raises an error if no response is found
   def graphql_mutation_response(mutation_name)
     graphql_data.fetch(GraphqlHelpers.fieldnamerize(mutation_name))