feat: Added cloneRepresentation function to ResourceUtil

* feat: added cloneRepresentation function to ResourceUtil

* fix: adapted to review

* fix: adapted to review

Co-authored-by: Arne Vandoorslaer <arne@digita.ai>

src/ldp/auxiliary/RdfValidator.ts

@@ -1,8 +1,7 @@
 import arrayifyStream from 'arrayify-stream';
 import type { RepresentationConverter } from '../../storage/conversion/RepresentationConverter';
 import { INTERNAL_QUADS } from '../../util/ContentTypes';
-import { guardedStreamFrom } from '../../util/StreamUtil';
-import { BasicRepresentation } from '../representation/BasicRepresentation';
+import { cloneRepresentation } from '../../util/ResourceUtil';
 import type { Representation } from '../representation/Representation';
 import { Validator } from './Validator';
 
@@ -23,23 +22,22 @@ export class RdfValidator extends Validator {
     if (representation.metadata.contentType === INTERNAL_QUADS) {
       return;
     }
-
-    // eslint-disable-next-line unicorn/expiring-todo-comments
-    // TODO: Everything below should be part of a utility cloneRepresentation function.
-
     const identifier = { path: representation.metadata.identifier.value };
-
-    // Read data in memory first so it does not get lost
-    const data = await arrayifyStream(representation.data);
     const preferences = { type: { [INTERNAL_QUADS]: 1 }};
-
-    // Creating new representation since converter might edit metadata
-    const tempRepresentation = new BasicRepresentation(data, identifier, representation.metadata.contentType);
-    const result = await this.converter.handleSafe({ identifier, representation: tempRepresentation, preferences });
+    let result;
+    try {
+      // Creating new representation since converter might edit metadata
+      const tempRepresentation = await cloneRepresentation(representation);
+      result = await this.converter.handleSafe({
+        identifier,
+        representation: tempRepresentation,
+        preferences,
+      });
+    } catch (error: unknown) {
+      representation.data.destroy();
+      throw error;
+    }
     // Drain stream to make sure data was parsed correctly
     await arrayifyStream(result.data);
-
-    // Stream has been drained so need to create new stream
-    representation.data = guardedStreamFrom(data);
   }
 }

src/util/ResourceUtil.ts

@@ -1,7 +1,12 @@
+import arrayifyStream from 'arrayify-stream';
 import { DataFactory } from 'n3';
 import type { NamedNode, Quad } from 'rdf-js';
+import { BasicRepresentation } from '../ldp/representation/BasicRepresentation';
+import type { Representation } from '../ldp/representation/Representation';
 import { RepresentationMetadata } from '../ldp/representation/RepresentationMetadata';
 import { pushQuad } from './QuadUtil';
+import { guardedStreamFrom } from './StreamUtil';
+
 import { LDP, RDF } from './Vocabularies';
 
 /**
@@ -33,3 +38,21 @@ export function generateContainmentQuads(containerURI: NamedNode, childURIs: str
   return new RepresentationMetadata(containerURI,
     { [LDP.contains]: childURIs.map(DataFactory.namedNode) }).quads();
 }
+
+/**
+ * Helper function to clone a representation, the original representation can still be used.
+ * This function loads the entire stream in memory.
+ * @param representation - The representation to clone.
+ *
+ * @returns The cloned representation.
+ */
+export async function cloneRepresentation(representation: Representation): Promise<BasicRepresentation> {
+  const data = await arrayifyStream(representation.data);
+  const result = new BasicRepresentation(
+    data,
+    new RepresentationMetadata(representation.metadata),
+    representation.binary,
+  );
+  representation.data = guardedStreamFrom(data);
+  return result;
+}

test/unit/ldp/auxiliary/RdfValidator.test.ts

@@ -39,6 +39,6 @@ describe('An RdfValidator', (): void => {
     const representation = new BasicRepresentation('data', 'content-type');
     await expect(validator.handle(representation)).rejects.toThrow('bad data!');
     // Make sure the data on the readable has not been reset
-    expect(representation.data.readableEnded).toBe(true);
+    expect(representation.data.destroyed).toBe(true);
   });
 });

test/unit/util/ResourceUtil.test.ts

@@ -0,0 +1,27 @@
+import { BasicRepresentation } from '../../../src/ldp/representation/BasicRepresentation';
+import type { Representation } from '../../../src/ldp/representation/Representation';
+import * as resourceUtils from '../../../src/util/ResourceUtil';
+import 'jest-rdf';
+
+describe('ResourceUtil', (): void => {
+  let representation: Representation;
+
+  beforeEach(async(): Promise<void> => {
+    representation = new BasicRepresentation('data', 'metadata');
+  });
+
+  describe('cloneRepresentation', (): void => {
+    it('returns a clone of the passed representation.', async(): Promise<void> => {
+      const res = await resourceUtils.cloneRepresentation(representation);
+      expect(res.binary).toBe(representation.binary);
+      expect(res.metadata.identifier).toBe(representation.metadata.identifier);
+      expect(res.metadata.contentType).toBe(representation.metadata.contentType);
+    });
+
+    it('ensures that original representation does not update when the clone is updated.', async(): Promise<void> => {
+      const res = await resourceUtils.cloneRepresentation(representation);
+      res.metadata.contentType = 'typetype';
+      expect(representation.metadata.contentType).not.toBe(res.metadata.contentType);
+    });
+  });
+});