Update events and tests.

- Update event code naming. Similar to JSON-LD error code style. Code
  name is just the condition detected, not the action that might be
  taken.
- Relative reference events now at call sites.
- No-value events now at call sites.
- Remove some special-case event handlers. Not needed when events happen
  outside `_expandIri`.
- **BREAKING**: Handle special non-normaitve spec edge case where value
  for `@id` can expand into null. Behavior changing to *not* output
  invalid JSON-LD. This can change triples in odd edge cases.
- Add eventCodeLog test feature to test sequence of events codes.
- Update tests.

Author: davidlehn

CHANGELOG.md

@@ -1,18 +1,32 @@
 # jsonld ChangeLog
 
+### Changed
+- Change EARL Assertor to Digital Bazaar, Inc.
+- Update eslint dependencies.
+- **BREAKING**: Handle spec edge case where value for `@id` can expand into
+  null. Behavior is changing to *not* output invalid JSON-LD and *potentially*
+  outputing an extra blank node. The input in question is something like
+  `{"@id":"@RESERVED", ...}` where `@RESERVED` will expand into `null`. Rather
+  than outputing invalid `{"@id": null, ...}`, the new behavior will drop
+  `@id`. When going to RDF this can cause slightly different output.
+  Specifically, a `{}` value may exist and create a blank node. Please file an
+  issue if this behavior causes issues. It is expected to be better addressed
+  in a future spec.
+  - Related [issue](https://github.com/w3c/json-ld-api/issues/480).
+  - Normative [toRdf test case](https://w3c.github.io/json-ld-api/tests/toRdf-manifest.html#te122)
+    *that now fails*.
+  - Non-normative [expand test case](https://w3c.github.io/json-ld-api/tests/expand-manifest.html#t0122)
+    that now fails.
+
 ### Added
 - Support benchmarks in Karma tests.
 - Support test environment in EARL output.
 - Support benchmark output in EARL output.
 - Benchmark comparison tool.
-- Event handler option `"eventHandler"` to allow custom handling of warnings and
-  potentially other events in the future. Handles event replay for cached
+- Event handler option `"eventHandler"` to allow custom handling of warnings
+  and potentially other events in the future. Handles event replay for cached
   contexts.
 
-### Changed
-- Change EARL Assertor to Digital Bazaar, Inc.
-- Update eslint dependencies.
-
 ## 6.0.0 - 2022-06-06
 
 ### Changed

lib/context.js

@@ -226,8 +226,25 @@ api.process = async ({
           '@context must be an absolute IRI.',
           'jsonld.SyntaxError', {code: 'invalid vocab mapping', context: ctx});
       } else {
-        rval['@vocab'] = _expandIri(rval, value, {vocab: true, base: true},
+        const vocab = _expandIri(rval, value, {vocab: true, base: true},
           undefined, undefined, options);
+        if(!_isAbsoluteIri(vocab)) {
+          if(options.eventHandler) {
+            _handleEvent({
+              event: {
+                type: ['JsonLdEvent'],
+                code: 'relative @vocab reference',
+                level: 'warning',
+                message: 'Relative @vocab reference found.',
+                details: {
+                  vocab
+                }
+              },
+              options
+            });
+          }
+        }
+        rval['@vocab'] = vocab;
       }
       defined.set('@vocab', true);
     }
@@ -497,10 +514,11 @@ api.createTermDefinition = ({
       _handleEvent({
         event: {
           type: ['JsonLdEvent'],
-          code: 'invalid reserved term',
+          code: 'reserved term',
           level: 'warning',
           message:
-            'Terms beginning with "@" are reserved for future use and ignored.',
+            'Terms beginning with "@" are ' +
+            'reserved for future use and dropped.',
           details: {
             term
           }
@@ -592,11 +610,11 @@ api.createTermDefinition = ({
         _handleEvent({
           event: {
             type: ['JsonLdEvent'],
-            code: 'invalid reserved value',
+            code: 'reserved @reverse value',
             level: 'warning',
             message:
-              'Values beginning with "@" are reserved for future use and' +
-              ' ignored.',
+              '@reverse values beginning with "@" are ' +
+              'reserved for future use and dropped.',
             details: {
               reverse
             }
@@ -641,11 +659,11 @@ api.createTermDefinition = ({
         _handleEvent({
           event: {
             type: ['JsonLdEvent'],
-            code: 'invalid reserved value',
+            code: 'reserved @id value',
             level: 'warning',
             message:
-              'Values beginning with "@" are reserved for future use and' +
-              ' ignored.',
+              '@id values beginning with "@" are ' +
+              'reserved for future use and dropped.',
             details: {
               id
             }
@@ -1171,22 +1189,8 @@ function _expandIri(activeCtx, value, relativeTo, localCtx, defined, options) {
     });
     if(expandedResult !== undefined) {
       value = expandedResult;
-    } else {
-      if(options.eventHandler) {
-        _handleEvent({
-          event: {
-            type: ['JsonLdEvent'],
-            code: 'relative IRI after expansion',
-            level: 'warning',
-            message: 'Expansion resulted in a relative IRI.',
-            details: {
-              value
-            }
-          },
-          options
-        });
-      }
     }
+    // NOTE: relative reference events emitted at calling sites as needed
   }
 
   return value;

lib/events.js

@@ -101,16 +101,23 @@ function _handle({event, handlers}) {
 }
 
 const _notSafeEventCodes = new Set([
-  'dropping empty object',
-  'dropping free-floating scalar',
-  'dropping object with only @id',
-  'dropping object with only @list',
-  'dropping object with only @value',
+  'empty object',
+  'free-floating scalar',
   'invalid @language value',
-  'invalid property expansion',
-  'invalid reserved term',
-  'no value after expansion',
-  'relative IRI after expansion'
+  'invalid property',
+  // NOTE: spec edge case
+  'null @id value',
+  'null @value value',
+  'object with only @id',
+  'object with only @language',
+  'object with only @list',
+  'object with only @value',
+  'relative @id reference',
+  'relative @type reference',
+  'relative @vocab reference',
+  'reserved @id value',
+  'reserved @reverse value',
+  'reserved term'
 ]);
 
 // safe handler that rejects unsafe warning conditions