Linter: add rule to remove empty then else

src/extension/alterschema/CMakeLists.txt

@@ -60,6 +60,8 @@ sourcemeta_library(NAMESPACE sourcemeta PROJECT core NAME alterschema
     linter/max_contains_without_contains.h
     linter/min_contains_without_contains.h
     linter/modern_official_dialect_with_empty_fragment.h
+    linter/then_empty.h
+    linter/else_empty.h
     linter/then_without_if.h)
 
 if(SOURCEMETA_CORE_INSTALL)

src/extension/alterschema/alterschema.cc

@@ -50,6 +50,7 @@ contains_any(const Vocabularies &container,
 #include "linter/duplicate_anyof_branches.h"
 #include "linter/duplicate_enum_values.h"
 #include "linter/duplicate_required_values.h"
+#include "linter/else_empty.h"
 #include "linter/else_without_if.h"
 #include "linter/enum_to_const.h"
 #include "linter/enum_with_type.h"
@@ -69,6 +70,7 @@ contains_any(const Vocabularies &container,
 #include "linter/pattern_properties_default.h"
 #include "linter/properties_default.h"
 #include "linter/single_type_array.h"
+#include "linter/then_empty.h"
 #include "linter/then_without_if.h"
 #include "linter/unevaluated_items_default.h"
 #include "linter/unevaluated_properties_default.h"
@@ -98,6 +100,8 @@ auto add(SchemaTransformer &bundle, const AlterSchemaMode mode)
   bundle.add<IfWithoutThenElse>();
   bundle.add<MaxContainsWithoutContains>();
   bundle.add<MinContainsWithoutContains>();
+  bundle.add<ThenEmpty>();
+  bundle.add<ElseEmpty>();
   bundle.add<ThenWithoutIf>();
   bundle.add<DependenciesPropertyTautology>();
   bundle.add<DependentRequiredTautology>();

src/extension/alterschema/linter/else_empty.h

@@ -0,0 +1,26 @@
+class ElseEmpty final : public SchemaTransformRule {
+public:
+  ElseEmpty()
+      : SchemaTransformRule{"else_empty",
+                            "Setting the `else` keyword to the empty schema "
+                            "does not add any further constraint"} {};
+
+  [[nodiscard]] auto
+  condition(const JSON &schema, const JSON &, const Vocabularies &vocabularies,
+            const SchemaFrame &, const SchemaFrame::Location &,
+            const SchemaWalker &, const SchemaResolver &) const
+      -> SchemaTransformRule::Result override {
+    return contains_any(
+               vocabularies,
+               {"https://json-schema.org/draft/2020-12/vocab/applicator",
+                "https://json-schema.org/draft/2019-09/vocab/applicator",
+                "http://json-schema.org/draft-07/schema#"}) &&
+           schema.is_object() && schema.defines("if") &&
+           schema.defines("else") && is_schema(schema.at("else")) &&
+           ((schema.at("else").is_object() && schema.at("else").empty()) ||
+            (schema.at("else").is_boolean() && schema.at("else").to_boolean() &&
+             !(schema.at("if").is_boolean() && schema.at("if").to_boolean())));
+  }
+
+  auto transform(JSON &schema) const -> void override { schema.erase("else"); }
+};

src/extension/alterschema/linter/then_empty.h

@@ -0,0 +1,26 @@
+class ThenEmpty final : public SchemaTransformRule {
+public:
+  ThenEmpty()
+      : SchemaTransformRule{"then_empty",
+                            "Setting the `then` keyword to the empty schema "
+                            "does not add any further constraint"} {};
+
+  [[nodiscard]] auto
+  condition(const JSON &schema, const JSON &, const Vocabularies &vocabularies,
+            const SchemaFrame &, const SchemaFrame::Location &,
+            const SchemaWalker &, const SchemaResolver &) const
+      -> SchemaTransformRule::Result override {
+    return contains_any(
+               vocabularies,
+               {"https://json-schema.org/draft/2020-12/vocab/applicator",
+                "https://json-schema.org/draft/2019-09/vocab/applicator",
+                "http://json-schema.org/draft-07/schema#"}) &&
+           schema.is_object() && schema.defines("if") &&
+           schema.defines("then") && is_schema(schema.at("then")) &&
+           ((schema.at("then").is_object() && schema.at("then").empty()) ||
+            (schema.at("then").is_boolean() && schema.at("then").to_boolean() &&
+             !(schema.at("if").is_boolean() && schema.at("if").to_boolean())));
+  }
+
+  auto transform(JSON &schema) const -> void override { schema.erase("then"); }
+};

test/alterschema/alterschema_lint_2019_09_test.cc

@@ -2032,3 +2032,105 @@ TEST(AlterSchema_lint_2019_09, modern_official_dialect_with_empty_fragment_3) {
 
   EXPECT_EQ(document, expected);
 }
+
+TEST(AlterSchema_lint_2019_09, then_empty_1) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2019-09/schema",
+    "if": {
+      "properties": {
+        "flag": {
+          "const": true
+        }
+      }
+    },
+    "then": {}
+  })JSON");
+
+  LINT_AND_FIX_FOR_READABILITY(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2019-09/schema"
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_2019_09, else_empty_1) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2019-09/schema",
+    "if": {
+      "properties": {
+        "flag": {
+          "const": true
+        }
+      }
+    },
+    "else": {}
+  })JSON");
+
+  LINT_AND_FIX_FOR_READABILITY(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2019-09/schema"
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_2019_09, then_empty_2) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2019-09/schema",
+    "if": {
+      "properties": {
+        "flag": {
+          "const": true
+        }
+      }
+    },
+    "then": {},
+    "else": {}
+  })JSON");
+
+  LINT_AND_FIX_FOR_READABILITY(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2019-09/schema"
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_2019_09, else_empty_2) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2019-09/schema",
+    "if": {
+      "properties": {
+        "flag": {
+          "const": true
+        }
+      }
+    },
+    "then": {
+      "type": "string"
+    },
+    "else": {}
+  })JSON");
+
+  LINT_AND_FIX_FOR_READABILITY(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2019-09/schema",
+    "if": {
+      "properties": {
+        "flag": {
+          "const": true
+        }
+      }
+    },
+    "then": {
+      "type": "string"
+    }
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}

test/alterschema/alterschema_lint_2020_12_test.cc

@@ -2207,3 +2207,164 @@ TEST(AlterSchema_lint_2020_12, modern_official_dialect_with_empty_fragment_3) {
 
   EXPECT_EQ(document, expected);
 }
+
+TEST(AlterSchema_lint_2020_12, then_empty_1) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "if": {
+      "properties": {
+        "flag": {
+          "const": true
+        }
+      }
+    },
+    "then": {}
+  })JSON");
+
+  LINT_AND_FIX_FOR_READABILITY(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema"
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_2020_12, else_empty_1) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "if": {
+      "properties": {
+        "flag": {
+          "const": true
+        }
+      }
+    },
+    "else": {}
+  })JSON");
+
+  LINT_AND_FIX_FOR_READABILITY(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema"
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_2020_12, then_empty_2) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "if": {
+      "properties": {
+        "flag": {
+          "const": true
+        }
+      }
+    },
+    "then": {},
+    "else": {}
+  })JSON");
+
+  LINT_AND_FIX_FOR_READABILITY(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema"
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_2020_12, else_empty_2) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "if": {
+      "properties": {
+        "flag": {
+          "const": true
+        }
+      }
+    },
+    "then": {
+      "type": "string"
+    },
+    "else": {}
+  })JSON");
+
+  LINT_AND_FIX_FOR_READABILITY(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "if": {
+      "properties": {
+        "flag": {
+          "const": true
+        }
+      }
+    },
+    "then": {
+      "type": "string"
+    }
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_2020_12, else_empty_3) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "if": {
+      "properties": {
+        "flag": {
+          "const": true
+        }
+      }
+    },
+    "else": true
+  })JSON");
+
+  LINT_AND_FIX_FOR_READABILITY(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema"
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_2020_12, then_empty_3) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "if": {
+      "properties": {
+        "flag": {
+          "const": true
+        }
+      }
+    },
+    "then": true
+  })JSON");
+
+  LINT_AND_FIX_FOR_READABILITY(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema"
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(AlterSchema_lint_2020_12, then_empty_4) {
+  sourcemeta::core::JSON document = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "then": {}
+  })JSON");
+
+  LINT_AND_FIX_FOR_READABILITY(document);
+
+  const sourcemeta::core::JSON expected = sourcemeta::core::parse_json(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema"
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}