test: characterize Client#parse handling of inline named fragments

test/test_parse_fragment_characterization.rb

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+# frozen_string_literal: true
+require "graphql"
+require "graphql/client"
+require "minitest/autorun"
+
+# Characterization tests pinning the CURRENT behavior of how Client#parse handles
+# *inline named fragments* (a `fragment Name on Type { ... }` definition that lives in
+# the same document as the operation that spreads `...Name`), as opposed to fragments
+# bound to Ruby constants and spread by their constant path.
+#
+# These behaviors are exercised today only incidentally (the existing
+# `test_client_parse_query_fragment_document` mixes a local spread with a constant
+# spread). They are isolated here so that a future refactor of the fragment-resolution
+# step in `Client#parse` cannot change them silently.
+class TestParseFragmentCharacterization < Minitest::Test
+  class UserType < GraphQL::Schema::Object
+    field :id, ID, null: false
+    field :name, String, null: false
+    field :login, String, null: false
+    field :friends, "[TestParseFragmentCharacterization::UserType]", null: false do
+      argument :first, Int, required: false
+    end
+  end
+
+  class QueryType < GraphQL::Schema::Object
+    field :viewer, UserType, null: false
+    field :user, UserType, null: true do
+      argument :id, ID, required: true
+    end
+  end
+
+  class Schema < GraphQL::Schema
+    query(QueryType)
+  end
+
+  module Temp
+  end
+
+  def setup
+    @client = GraphQL::Client.new(schema: Schema)
+    @client.document_tracking_enabled = true
+  end
+
+  def teardown
+    Temp.constants.each { |sym| Temp.send(:remove_const, sym) }
+  end
+
+  # A `...Name` spread that refers to a fragment defined in the SAME document — with no
+  # Ruby constant named `Name` anywhere — is resolved locally: the fragment definition is
+  # kept and renamed with the document's constant path, and the spread is rewritten to the
+  # renamed name. No ValidationError is raised and no constant lookup is required.
+  def test_local_named_fragment_spread_resolves_without_a_constant
+    Temp.const_set :Doc, @client.parse(<<-'GRAPHQL')
+      query Profile {
+        user(id: 4) {
+          ...UserFields
+        }
+      }
+
+      fragment UserFields on User {
+        id
+        name
+      }
+    GRAPHQL
+
+    op = Temp::Doc::Profile
+    refute_nil op
+    query_string = op.document.to_query_string
+
+    assert_includes query_string, "query TestParseFragmentCharacterization__Temp__Doc__Profile"
+    assert_includes query_string, "fragment TestParseFragmentCharacterization__Temp__Doc__UserFields on User"
+    # the spread points at the renamed local fragment, not a bare `...UserFields`
+    assert_includes query_string, "...TestParseFragmentCharacterization__Temp__Doc__UserFields"
+    refute_match(/\.\.\.UserFields\b/, query_string)
+  end
+
+  # Transitive local fragments (a local fragment that itself spreads another local
+  # fragment) are all resolved and renamed locally, and the operation's sliced document
+  # carries the full transitive dependency chain.
+  def test_transitive_local_named_fragments_resolve
+    Temp.const_set :Doc, @client.parse(<<-'GRAPHQL')
+      query Profile {
+        user(id: 4) {
+          ...Outer
+        }
+      }
+
+      fragment Outer on User {
+        id
+        ...Inner
+      }
+
+      fragment Inner on User {
+        name
+      }
+    GRAPHQL
+
+    document = Temp::Doc::Profile.document
+    # operation + both transitively-required fragments
+    assert_equal 3, document.definitions.size
+    query_string = document.to_query_string
+    assert_includes query_string, "...TestParseFragmentCharacterization__Temp__Doc__Outer"
+    assert_includes query_string, "...TestParseFragmentCharacterization__Temp__Doc__Inner"
+    assert_includes query_string, "fragment TestParseFragmentCharacterization__Temp__Doc__Inner on User"
+  end
+
+  # For a document with multiple independent operations, each operation's `document` is
+  # SLICED to just that operation plus its own fragment dependencies, while
+  # `source_document` retains every sibling definition from the original parse.
+  def test_source_document_retains_siblings_while_document_is_sliced
+    Temp.const_set :Doc, @client.parse(<<-'GRAPHQL')
+      query A {
+        user(id: 4) {
+          ...FieldsA
+        }
+      }
+
+      query B {
+        viewer {
+          ...FieldsB
+        }
+      }
+
+      fragment FieldsA on User {
+        id
+      }
+
+      fragment FieldsB on User {
+        name
+      }
+    GRAPHQL
+
+    a = Temp::Doc::A
+    # sliced: query A + fragment FieldsA only
+    assert_equal 2, a.document.definitions.size
+    # source: all four definitions from the original document
+    assert_equal 4, a.source_document.definitions.size
+  end
+end