fix: Introspection OrderArg returns null inputFields (#1633)

## Relevant issue(s)

Resolves #1632 
Resolves #1502 
Resolves #1463

## Description

This PR adds an introspection test that identifies an issue with
`orderArg`.

## Tasks

- [x] I made sure the code is well commented, particularly
hard-to-understand areas.
- [x] I made sure the repository-held documentation is changed
accordingly.
- [x] I made sure the pull request title adheres to the conventional
commit style (the subset used in the project can be found in
[tools/configs/chglog/config.yml](tools/configs/chglog/config.yml)).
- [x] I made sure to discuss its limitations such as threats to
validity, vulnerability to mistake and misuse, robustness to
invalidation of assumptions, resource requirements, ...

## How has this been tested?

`make test`

Specify the platform(s) on which this was tested:
- MacOS

request/graphql/schema/generate.go

@@ -1116,20 +1116,14 @@ func (g *Generator) genTypeOrderArgInput(obj *gql.Object) *gql.InputObject {
 					continue
 				}
 				typeMap := g.manager.schema.TypeMap()
+				configType, isOrderable := typeMap[genTypeName(field.Type, "OrderArg")]
 				if gql.IsLeafType(field.Type) { // only Scalars, and enums
 					fields[field.Name] = &gql.InputObjectFieldConfig{
 						Type: typeMap["Ordering"],
 					}
-				} else { // sub objects
-					configType, isOrderable := typeMap[genTypeName(field.Type, "OrderArg")]
-					if !isOrderable {
-						fields[field.Name] = &gql.InputObjectFieldConfig{
-							Type: &gql.InputObjectField{},
-						}
-					} else {
-						fields[field.Name] = &gql.InputObjectFieldConfig{
-							Type: configType,
-						}
+				} else if isOrderable { // sub objects
+					fields[field.Name] = &gql.InputObjectFieldConfig{
+						Type: configType,
 					}
 				}
 			}

tests/integration/explain/debug/with_order_join_test.go

@@ -134,21 +134,7 @@ func TestDebugExplainRequestWhereParentIsOrderedByItsRelatedChild(t *testing.T)
 					}
 				}`,
 
-				ExpectedPatterns: []dataMap{
-					{
-						"explain": dataMap{
-							"selectTopNode": dataMap{
-								"orderNode": dataMap{
-									"selectNode": dataMap{
-										"typeIndexJoin": dataMap{
-											"typeJoinMany": normalTypeJoinPattern,
-										},
-									},
-								},
-							},
-						},
-					},
-				},
+				ExpectedError: "Argument \"order\" has invalid value {articles: {name: ASC}}.\nIn field \"articles\": Unknown field.",
 			},
 		},
 	}

tests/integration/explain/default/with_order_join_test.go

@@ -180,37 +180,7 @@ func TestDefaultExplainRequestWhereParentIsOrderedByItsRelatedChild(t *testing.T
 					}
 				}`,
 
-				ExpectedPatterns: []dataMap{
-					{
-						"explain": dataMap{
-							"selectTopNode": dataMap{
-								"orderNode": dataMap{
-									"selectNode": dataMap{
-										"typeIndexJoin": normalTypeJoinPattern,
-									},
-								},
-							},
-						},
-					},
-				},
-
-				ExpectedTargets: []testUtils.PlanNodeTargetCase{
-					{
-						TargetNodeName:    "orderNode",
-						IncludeChildNodes: false,
-						ExpectedAttributes: dataMap{
-							"orderings": []dataMap{
-								{
-									"direction": "ASC",
-									"fields": []string{
-										"articles",
-										"name",
-									},
-								},
-							},
-						},
-					},
-				},
+				ExpectedError: "Argument \"order\" has invalid value {articles: {name: ASC}}.\nIn field \"articles\": Unknown field.",
 			},
 		},
 	}

tests/integration/explain/execute/with_order_test.go

@@ -285,31 +285,7 @@ func TestExecuteExplainRequestWhereParentFieldIsOrderedByChildField(t *testing.T
 					}
 				}`,
 
-				ExpectedFullGraph: []dataMap{
-					{
-						"explain": dataMap{
-							"executionSuccess": true,
-							"sizeOfResult":     2,
-							"planExecutions":   uint64(3),
-							"selectTopNode": dataMap{
-								"orderNode": dataMap{
-									"iterations": uint64(3),
-									"selectNode": dataMap{
-										"iterations":    uint64(3),
-										"filterMatches": uint64(2),
-										"typeIndexJoin": dataMap{
-											"iterations": uint64(3),
-											"scanNode": dataMap{
-												"iterations": uint64(3),
-												"docFetches": uint64(3),
-											},
-										},
-									},
-								},
-							},
-						},
-					},
-				},
+				ExpectedError: "Argument \"order\" has invalid value {articles: {pages: ASC}}.\nIn field \"articles\": Unknown field.",
 			},
 		},
 	}

tests/integration/schema/default_fields.go

@@ -218,7 +218,7 @@ func buildFilterArg(objectName string, fields []argDef) Field {
 			"name": filterArgName,
 		}),
 		makeInputObject("_key", "IDOperatorBlock", nil),
-		makeInputObject("_not", "authorFilterArg", nil),
+		makeInputObject("_not", filterArgName, nil),
 		makeInputObject("_or", nil, map[string]any{
 			"kind": "INPUT_OBJECT",
 			"name": filterArgName,

tests/integration/schema/input_type_test.go

@@ -16,6 +16,109 @@ import (
 	testUtils "github.com/sourcenetwork/defradb/tests/integration"
 )
 
+func TestInputTypeOfOrderFieldWhereSchemaHasManyRelationType(t *testing.T) {
+	test := testUtils.TestCase{
+		Actions: []any{
+			testUtils.SchemaUpdate{
+				Schema: `
+					type user {
+						age: Int
+						name: String
+						points: Float
+						verified: Boolean
+						group: group
+					}
+
+					type group {
+						members: [user]
+					}
+				`,
+			},
+			testUtils.IntrospectionRequest{
+				Request: `
+					query {
+						__type (name: "group") {
+							name
+							fields {
+								name
+								args {
+									name
+									type {
+										name
+										ofType {
+											name
+											kind
+										}
+										inputFields {
+											name
+											type {
+												name
+												ofType {
+													name
+													kind
+												}
+											}
+										}
+									}
+								}
+							}
+						}
+					}
+				`,
+				ContainsData: map[string]any{
+					"__type": map[string]any{
+						"name": "group",
+						"fields": []any{
+							map[string]any{
+								// Asserting only on group, because it is the field that contains `order` info we are
+								// looking for, additionally wanted to reduce the noise of other elements that were getting
+								// dumped out which made the entire output horrible.
+								"name": "_group",
+								"args": append(
+									trimFields(
+										fields{
+											dockeyArg,
+											dockeysArg,
+											buildFilterArg("group", []argDef{
+												{
+													fieldName: "members",
+													typeName:  "userFilterArg",
+												},
+											}),
+											groupByArg,
+											limitArg,
+											offsetArg,
+										},
+										testInputTypeOfOrderFieldWhereSchemaHasRelationTypeArgProps,
+									),
+									map[string]any{
+										"name": "order",
+										"type": map[string]any{
+											"name":   "groupOrderArg",
+											"ofType": nil,
+											"inputFields": []any{
+												map[string]any{
+													"name": "_key",
+													"type": map[string]any{
+														"name":   "Ordering",
+														"ofType": nil,
+													},
+												},
+											},
+										},
+									},
+								).Tidy(),
+							},
+						},
+					},
+				},
+			},
+		},
+	}
+
+	testUtils.ExecuteTestCase(t, []string{"user", "group"}, test)
+}
+
 func TestInputTypeOfOrderFieldWhereSchemaHasRelationType(t *testing.T) {
 	test := testUtils.TestCase{
 		Actions: []any{