Support validating only against a metaschema

src/command_validate.cc

@@ -15,17 +15,13 @@ auto intelligence::jsonschema::cli::validate(
     const std::span<const std::string> &arguments) -> int {
   const auto options{
       parse_options(arguments, {"h", "http", "m", "metaschema"})};
-  CLI_ENSURE(options.at("").size() >= 2,
-             "You must pass a schema followed by an instance")
+  CLI_ENSURE(options.at("").size() >= 1, "You must pass a schema")
   const auto &schema_path{options.at("").at(0)};
-  const auto &instance_path{options.at("").at(1)};
   const auto custom_resolver{
       resolver(options, options.contains("h") || options.contains("http"))};
 
   const auto schema{sourcemeta::jsontoolkit::from_file(schema_path)};
 
-  // TODO: If not instance is passed, just validate the schema against its
-  // metaschema?
   if (options.contains("m") || options.contains("metaschema")) {
     const auto metaschema_template{sourcemeta::jsontoolkit::compile(
         sourcemeta::jsontoolkit::metaschema(schema, custom_resolver),
@@ -43,19 +39,23 @@ auto intelligence::jsonschema::cli::validate(
     }
   }
 
-  const auto schema_template{sourcemeta::jsontoolkit::compile(
-      schema, sourcemeta::jsontoolkit::default_schema_walker, custom_resolver,
-      sourcemeta::jsontoolkit::default_schema_compiler)};
+  bool result{true};
+  if (options.at("").size() >= 2) {
+    const auto &instance_path{options.at("").at(1)};
+    const auto schema_template{sourcemeta::jsontoolkit::compile(
+        schema, sourcemeta::jsontoolkit::default_schema_walker, custom_resolver,
+        sourcemeta::jsontoolkit::default_schema_compiler)};
 
-  const auto instance{sourcemeta::jsontoolkit::from_file(instance_path)};
+    const auto instance{sourcemeta::jsontoolkit::from_file(instance_path)};
 
-  const auto result{sourcemeta::jsontoolkit::evaluate(
-      schema_template, instance,
-      sourcemeta::jsontoolkit::SchemaCompilerEvaluationMode::Fast,
-      pretty_evaluate_callback)};
+    result = sourcemeta::jsontoolkit::evaluate(
+        schema_template, instance,
+        sourcemeta::jsontoolkit::SchemaCompilerEvaluationMode::Fast,
+        pretty_evaluate_callback);
 
-  if (result) {
-    log_verbose(options) << "Valid\n";
+    if (result) {
+      log_verbose(options) << "Valid\n";
+    }
   }
 
   return result ? EXIT_SUCCESS : EXIT_FAILURE;

src/main.cc

@@ -20,13 +20,14 @@ Global Options:
 
 Commands:
 
-   validate <schema.json> <instance.json> [--http/-h] [--metaschema/-m]
-
-       Validate an instance against a schema, printing error information, if
-       any, in a human-readable manner. The `--http/-h` option enables resolving
-       remote schemas over the HTTP protocol. The `--metaschema/-m` option
-       checks that the given schema is valid with respects to its dialect
-       metaschema.
+   validate <schema.json> [instance.json] [--http/-h] [--metaschema/-m]
+
+       If an instance is passed, validate it against the given schema.
+       Otherwise, validate the schema against its dialect metaschema. The
+       `--http/-h` option enables resolving remote schemas over the HTTP
+       protocol. The `--metaschema/-m` option checks that the given schema
+       is valid with respects to its dialect metaschema even if an instance
+       was passed.
 
    test [schema.json...] [--http/-h] [--metaschema/-m]
 

test/CMakeLists.txt

@@ -17,6 +17,8 @@ add_jsonschema_test_unix(validate_fail)
 add_jsonschema_test_unix(validate_fail_remote_no_http)
 add_jsonschema_test_unix(validate_non_supported)
 add_jsonschema_test_unix(validate_pass_with_metaschema)
+add_jsonschema_test_unix(validate_pass_only_metaschema)
+add_jsonschema_test_unix(validate_fail_only_metaschema)
 add_jsonschema_test_unix(bundle_non_remote)
 add_jsonschema_test_unix(bundle_remote_single_schema)
 add_jsonschema_test_unix(bundle_remote_no_http)

test/validate_fail_only_metaschema.sh

@@ -0,0 +1,29 @@
+#!/bin/sh
+
+set -o errexit
+set -o nounset
+
+TMP="$(mktemp -d)"
+clean() { rm -rf "$TMP"; }
+trap clean EXIT
+
+cat << 'EOF' > "$TMP/schema.json"
+{
+  "$schema": "http://json-schema.org/draft-04/schema#",
+  "properties": {
+    "foo": {
+      "type": 1
+    }
+  }
+}
+EOF
+
+"$1" validate "$TMP/schema.json" --metaschema && CODE="$?" || CODE="$?"
+
+if [ "$CODE" = "0" ]
+then
+  echo "FAIL" 1>&2
+  exit 1
+else
+  echo "PASS" 1>&2
+fi

test/validate_pass_only_metaschema.sh

@@ -0,0 +1,21 @@
+#!/bin/sh
+
+set -o errexit
+set -o nounset
+
+TMP="$(mktemp -d)"
+clean() { rm -rf "$TMP"; }
+trap clean EXIT
+
+cat << 'EOF' > "$TMP/schema.json"
+{
+  "$schema": "http://json-schema.org/draft-04/schema#",
+  "properties": {
+    "foo": {
+      "type": "string"
+    }
+  }
+}
+EOF
+
+"$1" validate "$TMP/schema.json"