Linter: create rule to remove empty fragment

src/core/jsonschema/official_resolver.in.cc

@@ -10,6 +10,12 @@ auto sourcemeta::core::schema_official_resolver(std::string_view identifier)
              "https://json-schema.org/draft/2020-12/hyper-schema") {
     return sourcemeta::core::parse_json(
         R"EOF(@METASCHEMA_HYPERSCHEMA_2020_12@)EOF");
+  } else if (identifier ==
+             "https://json-schema.org/draft/2020-12/hyper-schema#") {
+    auto schema = sourcemeta::core::parse_json(
+        R"EOF(@METASCHEMA_HYPERSCHEMA_2020_12@)EOF");
+    schema.at("$id").into(sourcemeta::core::JSON{identifier});
+    return schema;
   } else if (identifier ==
              "https://json-schema.org/draft/2020-12/meta/applicator") {
     return sourcemeta::core::parse_json(
@@ -54,8 +60,10 @@ auto sourcemeta::core::schema_official_resolver(std::string_view identifier)
 
     // Just for compatibility given that this is such a common issue
   } else if (identifier == "https://json-schema.org/draft/2020-12/schema#") {
-    return sourcemeta::core::parse_json(
+    auto schema = sourcemeta::core::parse_json(
         R"EOF(@METASCHEMA_JSONSCHEMA_2020_12@)EOF");
+    schema.at("$id").into(sourcemeta::core::JSON{identifier});
+    return schema;
 
     // JSON Schema 2019-09
   } else if (identifier == "https://json-schema.org/draft/2019-09/schema") {
@@ -65,6 +73,12 @@ auto sourcemeta::core::schema_official_resolver(std::string_view identifier)
              "https://json-schema.org/draft/2019-09/hyper-schema") {
     return sourcemeta::core::parse_json(
         R"EOF(@METASCHEMA_HYPERSCHEMA_2019_09@)EOF");
+  } else if (identifier ==
+             "https://json-schema.org/draft/2019-09/hyper-schema#") {
+    auto schema = sourcemeta::core::parse_json(
+        R"EOF(@METASCHEMA_HYPERSCHEMA_2019_09@)EOF");
+    schema.at("$id").into(sourcemeta::core::JSON{identifier});
+    return schema;
   } else if (identifier ==
              "https://json-schema.org/draft/2019-09/meta/applicator") {
     return sourcemeta::core::parse_json(
@@ -105,8 +119,10 @@ auto sourcemeta::core::schema_official_resolver(std::string_view identifier)
 
     // Just for compatibility given that this is such a common issue
   } else if (identifier == "https://json-schema.org/draft/2019-09/schema#") {
-    return sourcemeta::core::parse_json(
+    auto schema = sourcemeta::core::parse_json(
         R"EOF(@METASCHEMA_JSONSCHEMA_2019_09@)EOF");
+    schema.at("$id").into(sourcemeta::core::JSON{identifier});
+    return schema;
 
     // JSON Schema Draft7
   } else if (identifier == "http://json-schema.org/draft-07/schema#" ||

src/extension/alterschema/CMakeLists.txt

@@ -59,6 +59,7 @@ sourcemeta_library(NAMESPACE sourcemeta PROJECT core NAME alterschema
     linter/if_without_then_else.h
     linter/max_contains_without_contains.h
     linter/min_contains_without_contains.h
+    linter/modern_official_dialect_with_empty_fragment.h
     linter/then_without_if.h)
 
 if(SOURCEMETA_CORE_INSTALL)

src/extension/alterschema/alterschema.cc

@@ -63,6 +63,7 @@ contains_any(const Vocabularies &container,
 #include "linter/maximum_real_for_integer.h"
 #include "linter/min_contains_without_contains.h"
 #include "linter/minimum_real_for_integer.h"
+#include "linter/modern_official_dialect_with_empty_fragment.h"
 #include "linter/multiple_of_default.h"
 #include "linter/non_applicable_type_specific_keywords.h"
 #include "linter/pattern_properties_default.h"
@@ -109,6 +110,7 @@ auto add(SchemaTransformer &bundle, const AlterSchemaMode mode)
   bundle.add<DuplicateRequiredValues>();
   bundle.add<ConstWithType>();
   bundle.add<AdditionalItemsWithSchemaItems>();
+  bundle.add<ModernOfficialDialectWithEmptyFragment>();
   bundle.add<ExclusiveMaximumNumberAndMaximum>();
   bundle.add<ExclusiveMinimumNumberAndMinimum>();
 

src/extension/alterschema/linter/modern_official_dialect_with_empty_fragment.h

@@ -0,0 +1,36 @@
+class ModernOfficialDialectWithEmptyFragment final
+    : public SchemaTransformRule {
+public:
+  ModernOfficialDialectWithEmptyFragment()
+      : SchemaTransformRule{
+            "modern_official_dialect_with_empty_fragment",
+            "The official dialect URI of 2019-09 and newer versions must "
+            "not contain the empty fragment"} {};
+
+  [[nodiscard]] auto condition(const sourcemeta::core::JSON &schema,
+                               const sourcemeta::core::JSON &,
+                               const sourcemeta::core::Vocabularies &,
+                               const sourcemeta::core::SchemaFrame &,
+                               const sourcemeta::core::SchemaFrame::Location &,
+                               const sourcemeta::core::SchemaWalker &,
+                               const sourcemeta::core::SchemaResolver &) const
+      -> sourcemeta::core::SchemaTransformRule::Result override {
+    if (!schema.is_object() || !schema.defines("$schema") ||
+        !schema.at("$schema").is_string()) {
+      return false;
+    }
+
+    const auto &schema_value = schema.at("$schema").to_string();
+    return (
+        schema_value == "https://json-schema.org/draft/2019-09/schema#" ||
+        schema_value == "https://json-schema.org/draft/2019-09/hyper-schema#" ||
+        schema_value == "https://json-schema.org/draft/2020-12/schema#" ||
+        schema_value == "https://json-schema.org/draft/2020-12/hyper-schema#");
+  }
+
+  auto transform(sourcemeta::core::JSON &schema) const -> void override {
+    auto schema_value = schema.at("$schema").to_string();
+    schema_value.pop_back();
+    schema.at("$schema").into(sourcemeta::core::JSON{std::move(schema_value)});
+  }
+};

test/alterschema/alterschema_lint_2019_09_test.cc

@@ -1984,3 +1984,51 @@ TEST(AlterSchema_lint_2019_09, additional_items_with_schema_items_array_items) {
 
   EXPECT_EQ(document, expected);
 }
+
+TEST(AlterSchema_lint_2019_09, modern_official_dialect_with_empty_fragment_1) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2019-09/schema#",
+    "type": "string"
+  })JSON");
+
+  LINT_AND_FIX_FOR_READABILITY(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2019-09/schema",
+    "type": "string"
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_2019_09, modern_official_dialect_with_empty_fragment_2) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2019-09/hyper-schema#",
+    "type": "string"
+  })JSON");
+
+  LINT_AND_FIX_FOR_READABILITY(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2019-09/hyper-schema",
+    "type": "string"
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_2019_09, modern_official_dialect_with_empty_fragment_3) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2019-09/schema",
+    "type": "string"
+  })JSON");
+
+  LINT_AND_FIX_FOR_READABILITY(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2019-09/schema",
+    "type": "string"
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}

test/alterschema/alterschema_lint_2020_12_test.cc

@@ -2158,3 +2158,52 @@ TEST(AlterSchema_lint_2020_12, unnecessary_allof_wrapper_properties_4) {
 
   EXPECT_EQ(document, expected);
 }
+
+TEST(AlterSchema_lint_2020_12, modern_official_dialect_with_empty_fragment_1) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema#",
+    "type": "string"
+  })JSON");
+
+  LINT_AND_FIX_FOR_READABILITY(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "type": "string"
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_2020_12, modern_official_dialect_with_empty_fragment_2) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/hyper-schema#",
+    "type": "string"
+  })JSON");
+
+  LINT_AND_FIX_FOR_READABILITY(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/hyper-schema",
+    "type": "string"
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_2020_12, modern_official_dialect_with_empty_fragment_3) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "type": "string"
+  })JSON");
+
+  LINT_AND_FIX_FOR_READABILITY(document);
+
+  // Should remain unchanged since there's no empty fragment
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "type": "string"
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}