feat: add --json to lint command

docs/lint.markdown

@@ -3,7 +3,7 @@ Linting
 
 ```sh
 jsonschema lint [schemas-or-directories...]
-  [--fix/-f] [--verbose/-v] [--extension/-e <extension>]
+  [--fix/-f] [--json/-j] [--verbose/-v] [--extension/-e <extension>]
   [--ignore/-i <schemas-or-directories>]
 ```
 
@@ -61,6 +61,11 @@ result in the JSON Schema CLI *automatically* fixing the warning for you.
 ```sh
 jsonschema lint path/to/my/schema_1.json path/to/my/schema_2.json
 ```
+### Lint with JSON output
+
+```sh
+jsonschema lint path/to/my/schema.json --json
+```
 
 ### Lint every `.json` file in a given directory (recursively)
 

src/command_lint.cc

@@ -3,16 +3,18 @@
 #include <sourcemeta/core/jsonpointer.h>
 #include <sourcemeta/core/jsonschema.h>
 
-#include <cstdlib>  // EXIT_SUCCESS
+#include <cstdlib>  // EXIT_SUCCESS, EXIT_FAILURE
 #include <fstream>  // std::ofstream
 #include <iostream> // std::cerr, std::cout
+#include <sstream>  // std::ostringstream
 
 #include "command.h"
 #include "utils.h"
 
 auto sourcemeta::jsonschema::cli::lint(
     const std::span<const std::string> &arguments) -> int {
-  const auto options{parse_options(arguments, {"f", "fix"})};
+  const auto options{parse_options(arguments, {"f", "fix", "json", "j"})};
+  const bool output_json = options.contains("json") || options.contains("j");
 
   sourcemeta::core::SchemaTransformer bundle;
   sourcemeta::core::add(bundle,
@@ -27,6 +29,7 @@ auto sourcemeta::jsonschema::cli::lint(
                         sourcemeta::core::AlterSchemaCategory::SyntaxSugar);
 
   bool result{true};
+  auto errors_array = sourcemeta::core::JSON::make_array();
 
   if (options.contains("f") || options.contains("fix")) {
     for (const auto &entry :
@@ -47,29 +50,48 @@ auto sourcemeta::jsonschema::cli::lint(
                                  sourcemeta::core::schema_format_compare);
       output << "\n";
     }
-  } else {
-    for (const auto &entry :
-         for_each_json(options.at(""), parse_ignore(options),
-                       parse_extensions(options))) {
-      log_verbose(options) << "Linting: " << entry.first.string() << "\n";
-      const bool subresult = bundle.check(
-          entry.second, sourcemeta::core::schema_official_walker,
-          resolver(options),
-          [&entry](const auto &pointer, const auto &name, const auto &message) {
+  }
+  for (const auto &entry : for_each_json(options.at(""), parse_ignore(options),
+                                         parse_extensions(options))) {
+    log_verbose(options) << "Linting: " << entry.first.string() << "\n";
+    const bool subresult = bundle.check(
+        entry.second, sourcemeta::core::schema_official_walker,
+        resolver(options),
+        [&](const auto &pointer, const auto &name, const auto &message) {
+          if (output_json) {
+            auto error_obj = sourcemeta::core::JSON::make_object();
+
+            error_obj.assign("path",
+                             sourcemeta::core::JSON{entry.first.string()});
+            error_obj.assign("id", sourcemeta::core::JSON{name});
+            error_obj.assign("message", sourcemeta::core::JSON{message});
+
+            std::ostringstream pointer_stream;
+            sourcemeta::core::stringify(pointer, pointer_stream);
+            error_obj.assign("schemaLocation",
+                             sourcemeta::core::JSON{pointer_stream.str()});
+
+            errors_array.push_back(error_obj);
+          } else {
             std::cout << entry.first.string() << ":\n";
             std::cout << "  " << message << " (" << name << ")\n";
             std::cout << "    at schema location \"";
             sourcemeta::core::stringify(pointer, std::cout);
             std::cout << "\"\n";
-          });
+          }
+        });
 
-      if (subresult) {
-        log_verbose(options) << "PASS: " << entry.first.string() << "\n";
-      } else {
-        result = false;
-      }
+    if (!subresult) {
+      result = false;
     }
   }
+  if (output_json) {
+    auto output_json_object = sourcemeta::core::JSON::make_object();
+    output_json_object.assign("valid", sourcemeta::core::JSON{result});
+    output_json_object.assign("errors", sourcemeta::core::JSON{errors_array});
+    sourcemeta::core::prettify(output_json_object, std::cout);
+    std::cout << "\n";
+  }
 
   return result ? EXIT_SUCCESS : EXIT_FAILURE;
 }

src/main.cc

@@ -45,11 +45,12 @@ Global Options:
        Format the input schemas in-place or check they are formatted.
        This command does not support YAML schemas yet.
 
-   lint [schemas-or-directories...] [--fix/-f] [--extension/-e <extension>]
+   lint [schemas-or-directories...] [--fix/-f] [--json/-j] [--extension/-e <extension>]
         [--ignore/-i <schemas-or-directories>]
 
        Lint the input schemas and potentially fix the reported issues.
        The --fix/-f option is not supported when passing YAML schemas.
+       Use --json/-j to output lint errors in JSON.
 
    bundle <schema.json|.yaml> [--http/-h] [--extension/-e <extension>]
           [--ignore/-i <schemas-or-directories>] [--without-id/-w]

test/CMakeLists.txt

@@ -167,6 +167,9 @@ add_jsonschema_test_unix(lint/fail_lint)
 add_jsonschema_test_unix(lint/fail_lint_yaml)
 add_jsonschema_test_unix(lint/fail_lint_fix_yaml)
 add_jsonschema_test_unix(lint/fail_lint_fix_yml)
+add_jsonschema_test_unix(lint/fail_lint_json)
+add_jsonschema_test_unix(lint/pass_lint_json)
+add_jsonschema_test_unix(lint/pass_lint_fix_json)
 add_jsonschema_test_unix(lint/fail_bigint)
 
 # Encode

test/lint/fail_lint_json.sh

@@ -0,0 +1,35 @@
+#!/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#",
+  "type": "string",
+  "enum": [ "foo" ]
+}
+EOF
+
+"$1" lint "$TMP/schema.json" --json >"$TMP/output.json" 2>&1 && CODE="$?" || CODE="$?"
+test "$CODE" = "1" || exit 1
+
+cat << EOF > "$TMP/expected.json"
+{
+  "valid": false,
+  "errors": [
+    {
+      "path": "$(realpath "$TMP")/schema.json",
+      "id": "enum_with_type",
+      "message": "Setting \`type\` alongside \`enum\` is considered an anti-pattern, as the enumeration choices already imply their respective types",
+      "schemaLocation": ""
+    }
+  ]
+}
+EOF
+
+diff "$TMP/output.json" "$TMP/expected.json"

test/lint/pass_lint_fix_json.sh

@@ -0,0 +1,36 @@
+#!/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-06/schema#",
+  "type": "string",
+  "enum": [ "foo" ]
+}
+EOF
+
+"$1" lint "$TMP/schema.json" --fix --json >"$TMP/output.json" 2>&1
+
+cat << EOF > "$TMP/expected.json"
+{
+  "valid": true,
+  "errors": []
+}
+EOF
+
+diff "$TMP/output.json" "$TMP/expected.json"
+
+cat << 'EOF' > "$TMP/expected_fixed.json"
+{
+  "$schema": "http://json-schema.org/draft-06/schema#",
+  "const": "foo"
+}
+EOF
+
+diff "$TMP/schema.json" "$TMP/expected_fixed.json"

test/lint/pass_lint_json.sh

@@ -0,0 +1,26 @@
+#!/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#",
+  "enum": [ "foo" ]
+}
+EOF
+
+"$1" lint "$TMP/schema.json" --json >"$TMP/output.json" 2>&1
+
+cat << EOF > "$TMP/expected.json"
+{
+  "valid": true,
+  "errors": []
+}
+EOF
+
+diff "$TMP/output.json" "$TMP/expected.json"