Add an implicit rule for minProperties

src/linter/CMakeLists.txt

@@ -46,6 +46,7 @@ noa_library(NAMESPACE sourcemeta PROJECT alterschema NAME linter
     implicit/max_contains_covered_by_max_items.h
     implicit/min_length_implicit.h
     implicit/min_properties_covered_by_required.h
+    implicit/min_properties_implicit.h
     implicit/multiple_of_implicit.h
     implicit/properties_implicit.h
 

src/linter/implicit/min_properties_implicit.h

@@ -0,0 +1,35 @@
+class MinPropertiesImplicit final : public Rule {
+public:
+  MinPropertiesImplicit()
+      : Rule{"min_properties_implicit",
+             "The `minProperties` keyword has a logical default of 0 or the "
+             "size of `required`"} {};
+
+  [[nodiscard]] auto
+  condition(const sourcemeta::jsontoolkit::JSON &schema, const std::string &,
+            const std::set<std::string> &vocabularies,
+            const sourcemeta::jsontoolkit::Pointer &) const -> bool override {
+    return contains_any(
+               vocabularies,
+               {"https://json-schema.org/draft/2020-12/vocab/validation",
+                "https://json-schema.org/draft/2019-09/vocab/validation",
+                "http://json-schema.org/draft-07/schema#",
+                "http://json-schema.org/draft-06/schema#",
+                "http://json-schema.org/draft-04/schema#"}) &&
+           schema.is_object() && schema.defines("type") &&
+           schema.at("type").is_string() &&
+           schema.at("type").to_string() == "object" &&
+           !schema.defines("minProperties");
+  }
+
+  auto transform(Transformer &transformer) const -> void override {
+    if (transformer.schema().defines("required") &&
+        transformer.schema().at("required").is_array()) {
+      transformer.assign("minProperties",
+                         sourcemeta::jsontoolkit::JSON{
+                             transformer.schema().at("required").size()});
+    } else {
+      transformer.assign("minProperties", sourcemeta::jsontoolkit::JSON{0});
+    }
+  }
+};

src/linter/linter.cc

@@ -65,6 +65,7 @@ template <typename T> auto every_item_is_boolean(const T &container) -> bool {
 #include "implicit/max_contains_covered_by_max_items.h"
 #include "implicit/min_length_implicit.h"
 #include "implicit/min_properties_covered_by_required.h"
+#include "implicit/min_properties_implicit.h"
 #include "implicit/multiple_of_implicit.h"
 #include "implicit/properties_implicit.h"
 // Superfluous
@@ -220,6 +221,7 @@ auto add(Bundle &bundle, const LinterCategory category) -> void {
       bundle.add<MaxContainsCoveredByMaxItems>();
       bundle.add<MinLengthImplicit>();
       bundle.add<MinPropertiesCoveredByRequired>();
+      bundle.add<MinPropertiesImplicit>();
       bundle.add<MultipleOfImplicit>();
       bundle.add<PropertiesImplicit>();
       break;

test/linter/2019_09_test.cc

@@ -1610,3 +1610,48 @@ TEST(Lint_2019_09, min_properties_covered_by_required_1) {
 
   EXPECT_EQ(document, expected);
 }
+
+TEST(Lint_2019_09, min_properties_implicit_1) {
+  sourcemeta::jsontoolkit::JSON document =
+      sourcemeta::jsontoolkit::parse(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "type": "object",
+    "required": [ "foo", "bar" ]
+  })JSON");
+
+  LINT_AND_FIX_FOR_ANALYSIS(document);
+
+  const sourcemeta::jsontoolkit::JSON expected =
+      sourcemeta::jsontoolkit::parse(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "type": "object",
+    "required": [ "foo", "bar" ],
+    "properties": {},
+    "minProperties": 2
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(Lint_2019_09, min_properties_implicit_2) {
+  sourcemeta::jsontoolkit::JSON document =
+      sourcemeta::jsontoolkit::parse(R"JSON({
+    "$schema": "https://json-schema.org/draft/2019-09/schema",
+    "type": "object",
+    "minProperties": 2,
+    "required": [ "foo", "bar" ]
+  })JSON");
+
+  LINT_AND_FIX_FOR_ANALYSIS(document);
+
+  const sourcemeta::jsontoolkit::JSON expected =
+      sourcemeta::jsontoolkit::parse(R"JSON({
+    "$schema": "https://json-schema.org/draft/2019-09/schema",
+    "type": "object",
+    "properties": {},
+    "required": [ "foo", "bar" ],
+    "minProperties": 2
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}

test/linter/2020_12_test.cc

@@ -1665,6 +1665,7 @@ TEST(Lint_2020_12, type_array_to_any_of_3) {
       {
         "type": "object",
         "properties": {},
+        "minProperties": 0,
         "additionalProperties": {
           "$anchor": "foo",
           "type": "string",
@@ -1763,3 +1764,48 @@ TEST(Lint_2020_12, min_properties_covered_by_required_1) {
 
   EXPECT_EQ(document, expected);
 }
+
+TEST(Lint_2020_12, min_properties_implicit_1) {
+  sourcemeta::jsontoolkit::JSON document =
+      sourcemeta::jsontoolkit::parse(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "type": "object",
+    "required": [ "foo", "bar" ]
+  })JSON");
+
+  LINT_AND_FIX_FOR_ANALYSIS(document);
+
+  const sourcemeta::jsontoolkit::JSON expected =
+      sourcemeta::jsontoolkit::parse(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "type": "object",
+    "required": [ "foo", "bar" ],
+    "properties": {},
+    "minProperties": 2
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(Lint_2020_12, min_properties_implicit_2) {
+  sourcemeta::jsontoolkit::JSON document =
+      sourcemeta::jsontoolkit::parse(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "type": "object",
+    "minProperties": 2,
+    "required": [ "foo", "bar" ]
+  })JSON");
+
+  LINT_AND_FIX_FOR_ANALYSIS(document);
+
+  const sourcemeta::jsontoolkit::JSON expected =
+      sourcemeta::jsontoolkit::parse(R"JSON({
+    "$schema": "https://json-schema.org/draft/2020-12/schema",
+    "type": "object",
+    "properties": {},
+    "required": [ "foo", "bar" ],
+    "minProperties": 2
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}

test/linter/draft4_test.cc

@@ -735,3 +735,48 @@ TEST(Lint_draft4, min_properties_covered_by_required_1) {
 
   EXPECT_EQ(document, expected);
 }
+
+TEST(Lint_draft4, min_properties_implicit_1) {
+  sourcemeta::jsontoolkit::JSON document =
+      sourcemeta::jsontoolkit::parse(R"JSON({
+    "$schema": "http://json-schema.org/draft-04/schema#",
+    "type": "object",
+    "required": [ "foo", "bar" ]
+  })JSON");
+
+  LINT_AND_FIX_FOR_ANALYSIS(document);
+
+  const sourcemeta::jsontoolkit::JSON expected =
+      sourcemeta::jsontoolkit::parse(R"JSON({
+    "$schema": "http://json-schema.org/draft-04/schema#",
+    "type": "object",
+    "required": [ "foo", "bar" ],
+    "properties": {},
+    "minProperties": 2
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(Lint_draft4, min_properties_implicit_2) {
+  sourcemeta::jsontoolkit::JSON document =
+      sourcemeta::jsontoolkit::parse(R"JSON({
+    "$schema": "http://json-schema.org/draft-04/schema#",
+    "type": "object",
+    "minProperties": 2,
+    "required": [ "foo", "bar" ]
+  })JSON");
+
+  LINT_AND_FIX_FOR_ANALYSIS(document);
+
+  const sourcemeta::jsontoolkit::JSON expected =
+      sourcemeta::jsontoolkit::parse(R"JSON({
+    "$schema": "http://json-schema.org/draft-04/schema#",
+    "type": "object",
+    "properties": {},
+    "required": [ "foo", "bar" ],
+    "minProperties": 2
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}

test/linter/draft6_test.cc

@@ -1124,3 +1124,48 @@ TEST(Lint_draft6, min_properties_covered_by_required_1) {
 
   EXPECT_EQ(document, expected);
 }
+
+TEST(Lint_draft6, min_properties_implicit_1) {
+  sourcemeta::jsontoolkit::JSON document =
+      sourcemeta::jsontoolkit::parse(R"JSON({
+    "$schema": "http://json-schema.org/draft-06/schema#",
+    "type": "object",
+    "required": [ "foo", "bar" ]
+  })JSON");
+
+  LINT_AND_FIX_FOR_ANALYSIS(document);
+
+  const sourcemeta::jsontoolkit::JSON expected =
+      sourcemeta::jsontoolkit::parse(R"JSON({
+    "$schema": "http://json-schema.org/draft-06/schema#",
+    "type": "object",
+    "required": [ "foo", "bar" ],
+    "properties": {},
+    "minProperties": 2
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(Lint_draft6, min_properties_implicit_2) {
+  sourcemeta::jsontoolkit::JSON document =
+      sourcemeta::jsontoolkit::parse(R"JSON({
+    "$schema": "http://json-schema.org/draft-06/schema#",
+    "type": "object",
+    "minProperties": 2,
+    "required": [ "foo", "bar" ]
+  })JSON");
+
+  LINT_AND_FIX_FOR_ANALYSIS(document);
+
+  const sourcemeta::jsontoolkit::JSON expected =
+      sourcemeta::jsontoolkit::parse(R"JSON({
+    "$schema": "http://json-schema.org/draft-06/schema#",
+    "type": "object",
+    "properties": {},
+    "required": [ "foo", "bar" ],
+    "minProperties": 2
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}

test/linter/draft7_test.cc

@@ -1232,3 +1232,48 @@ TEST(Lint_draft7, min_properties_covered_by_required_1) {
 
   EXPECT_EQ(document, expected);
 }
+
+TEST(Lint_draft7, min_properties_implicit_1) {
+  sourcemeta::jsontoolkit::JSON document =
+      sourcemeta::jsontoolkit::parse(R"JSON({
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "type": "object",
+    "required": [ "foo", "bar" ]
+  })JSON");
+
+  LINT_AND_FIX_FOR_ANALYSIS(document);
+
+  const sourcemeta::jsontoolkit::JSON expected =
+      sourcemeta::jsontoolkit::parse(R"JSON({
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "type": "object",
+    "required": [ "foo", "bar" ],
+    "properties": {},
+    "minProperties": 2
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}
+
+TEST(Lint_draft7, min_properties_implicit_2) {
+  sourcemeta::jsontoolkit::JSON document =
+      sourcemeta::jsontoolkit::parse(R"JSON({
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "type": "object",
+    "minProperties": 2,
+    "required": [ "foo", "bar" ]
+  })JSON");
+
+  LINT_AND_FIX_FOR_ANALYSIS(document);
+
+  const sourcemeta::jsontoolkit::JSON expected =
+      sourcemeta::jsontoolkit::parse(R"JSON({
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "type": "object",
+    "properties": {},
+    "required": [ "foo", "bar" ],
+    "minProperties": 2
+  })JSON");
+
+  EXPECT_EQ(document, expected);
+}