Attempt to resolve file-based references without requiring --resolve (#430)

Fixes: #425
Signed-off-by: Juan Cruz Viotti <[email protected]>

Author: jviotti

src/error.h

@@ -37,13 +37,25 @@ inline auto try_catch(const std::function<int()> &callback) noexcept -> int {
                      error.path())
                      .string()
               << "\n";
-    std::cerr << "\nThis is likely because you forgot to import such schema "
-                 "using --resolve/-r\n";
+
+    if (error.id().starts_with("file://")) {
+      std::cerr << "\nThis is likely because the file does not exist\n";
+    } else {
+      std::cerr << "\nThis is likely because you forgot to import such schema "
+                   "using --resolve/-r\n";
+    }
+
     return EXIT_FAILURE;
   } catch (const sourcemeta::core::SchemaResolutionError &error) {
     std::cerr << "error: " << error.what() << "\n  " << error.id() << "\n";
-    std::cerr << "\nThis is likely because you forgot to import such schema "
-                 "using --resolve/-r\n";
+
+    if (error.id().starts_with("file://")) {
+      std::cerr << "\nThis is likely because the file does not exist\n";
+    } else {
+      std::cerr << "\nThis is likely because you forgot to import such schema "
+                   "using --resolve/-r\n";
+    }
+
     return EXIT_FAILURE;
   } catch (const sourcemeta::core::SchemaUnknownDialectError &error) {
     std::cerr << "error: " << error.what() << "\n";

src/utils.cc

@@ -308,6 +308,17 @@ auto resolver(const std::map<std::string, std::vector<std::string>> &options,
     -> sourcemeta::core::SchemaResolver {
   sourcemeta::core::SchemaMapResolver dynamic_resolver{
       [remote, &options](std::string_view identifier) {
+        const sourcemeta::core::URI uri{std::string{identifier}};
+        if (uri.is_file()) {
+          const auto path{uri.to_path()};
+          log_verbose(options)
+              << "Attempting to read file reference from disk: "
+              << path.string() << "\n";
+          if (std::filesystem::exists(path)) {
+            return std::optional<sourcemeta::core::JSON>{read_file(path)};
+          }
+        }
+
         if (remote) {
           return fallback_resolver(options, identifier);
         } else {

test/CMakeLists.txt

@@ -99,6 +99,8 @@ add_jsonschema_test_unix(validate/pass_with_invalid_template)
 add_jsonschema_test_unix(validate/pass_with_invalid_template_verbose)
 add_jsonschema_test_unix(validate/pass_no_identifier_ref)
 add_jsonschema_test_unix(validate/pass_no_identifier_half_ref)
+add_jsonschema_test_unix(validate/pass_no_identifier_ref_without_resolve)
+add_jsonschema_test_unix(validate/fail_no_identifier_ref_without_resolve)
 add_jsonschema_test_unix(validate/fail_json)
 add_jsonschema_test_unix(validate/pass_json)
 add_jsonschema_test_unix(validate/pass_json_fast)

test/validate/fail_no_identifier_ref_without_resolve.sh

@@ -0,0 +1,33 @@
+#!/bin/sh
+
+set -o errexit
+set -o nounset
+
+TMP="$(mktemp -d)"
+clean() { rm -rf "$TMP"; }
+trap clean EXIT
+
+cat << 'EOF' > "$TMP/schema.json"
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$ref": "./schemas/other.json"
+}
+EOF
+
+cat << 'EOF' > "$TMP/instance.json"
+"foo bar"
+EOF
+
+"$1" validate "$TMP/schema.json" "$TMP/instance.json" --verbose > "$TMP/output.txt" 2>&1 \
+  && CODE="$?" || CODE="$?"
+test "$CODE" = "1" || exit 1
+
+cat << EOF > "$TMP/expected.txt"
+Attempting to read file reference from disk: $(realpath "$TMP")/schemas/other.json
+error: Could not resolve the reference to an external schema
+  file://$(realpath "$TMP")/schemas/other.json
+
+This is likely because the file does not exist
+EOF
+
+diff "$TMP/output.txt" "$TMP/expected.txt"

test/validate/pass_no_identifier_ref_without_resolve.sh

@@ -0,0 +1,38 @@
+#!/bin/sh
+
+set -o errexit
+set -o nounset
+
+TMP="$(mktemp -d)"
+clean() { rm -rf "$TMP"; }
+trap clean EXIT
+
+cat << 'EOF' > "$TMP/schema.json"
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$ref": "./schemas/other.json"
+}
+EOF
+
+mkdir -p "$TMP/schemas"
+
+cat << 'EOF' > "$TMP/schemas/other.json"
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "type": "string"
+}
+EOF
+
+cat << 'EOF' > "$TMP/instance.json"
+"foo bar"
+EOF
+
+"$1" validate "$TMP/schema.json" "$TMP/instance.json" --verbose > "$TMP/output.txt" 2>&1
+
+cat << EOF > "$TMP/expected.txt"
+Attempting to read file reference from disk: $(realpath "$TMP")/schemas/other.json
+ok: $(realpath "$TMP")/instance.json
+  matches $(realpath "$TMP")/schema.json
+EOF
+
+diff "$TMP/output.txt" "$TMP/expected.txt"