Lady’s Gitweb - Etiquette/blob - model.test.js

   1 // 📧🏷️ Étiquette ∷ model.test.js
   2 // ====================================================================
   3 //
   4 // Copyright © 2023 Lady [@ Lady’s Computer].
   5 //
   6 // This Source Code Form is subject to the terms of the Mozilla Public
   7 // License, v. 2.0. If a copy of the MPL was not distributed with this
   8 // file, You can obtain one at <https://mozilla.org/MPL/2.0/>.
   9
  10 import {
  11   assert,
  12   assertArrayIncludes,
  13   assertEquals,
  14   assertFalse,
  15   assertObjectMatch,
  16   assertStrictEquals,
  17   assertThrows,
  18   beforeEach,
  19   describe,
  20   it,
  21 } from "./dev-deps.js";
  22 import { TagSystem } from "./model.js";
  23
  24 describe("TagSystem", () => {
  25   it("[[Call]] throws", () => {
  26     assertThrows(() => {
  27       TagSystem();
  28     });
  29   });
  30
  31   it("[[Construct]] creates a new TagSystem", () => {
  32     assertStrictEquals(
  33       Object.getPrototypeOf(new TagSystem("example", "1972-12-31")),
  34       TagSystem.prototype,
  35     );
  36   });
  37
  38   it("[[Construct]] uses the identifier if provided", () => {
  39     assertStrictEquals(
  40       new TagSystem("example", "1972-12-31", "etaoin").identifier,
  41       "etaoin",
  42     );
  43   });
  44
  45   it("[[Construct]] uses an empty identifier if none is provided", () => {
  46     assertStrictEquals(
  47       new TagSystem("example", "1972-12-31").identifier,
  48       "",
  49     );
  50   });
  51
  52   it("[[Construct]] throws if provided an invalid domain", () => {
  53     assertThrows(() => {
  54       new TagSystem("example@example", "1972-12-31");
  55     });
  56     assertThrows(() => {
  57       new TagSystem("0.0.0.0", "1972-12-31");
  58     });
  59   });
  60
  61   it("[[Construct]] throws if provided an invalid date", () => {
  62     assertThrows(() => {
  63       new TagSystem("example", "1969");
  64     });
  65     assertThrows(() => {
  66       new TagSystem("example", "1972-12-31T00:00:00Z");
  67     });
  68   });
  69
  70   describe("::Tag", () => {
  71     let Tag;
  72     let system;
  73
  74     beforeEach(() => {
  75       system = new TagSystem("example", "1972-12-31");
  76       Tag = system.Tag;
  77     });
  78
  79     it("[[Get]] returns the same value every time", () => {
  80       assertStrictEquals(Tag, system.Tag);
  81     });
  82
  83     it("[[Call]] throws", () => {
  84       assertThrows(() => {
  85         Tag();
  86       });
  87     });
  88
  89     it("[[Construct]] returns a new Tag", () => {
  90       assertStrictEquals(
  91         Object.getPrototypeOf(new Tag()),
  92         Tag.prototype,
  93       );
  94     });
  95
  96     it('[[Construct]] defaults the kind to "Tag"', () => {
  97       assertStrictEquals(new Tag().kind, "Tag");
  98     });
  99
 100     it("[[Construct]] correctly sets the tag kind", () => {
 101       assertStrictEquals(
 102         new Tag("RelationshipTag").kind,
 103         "RelationshipTag",
 104       );
 105     });
 106
 107     it("[[Construct]] defaults the preferred label to the empty string", () => {
 108       assertEquals({ ...new Tag().prefLabel }, { "@value": "" });
 109     });
 110
 111     it("[[Construct]] correctly sets the preferred label to a simple string", () => {
 112       assertEquals(
 113         { ...new Tag("RelationshipTag", "Shadow, Me").prefLabel },
 114         { "@value": "Shadow, Me" },
 115       );
 116     });
 117
 118     it("[[Construct]] initializes tag identifiers to null", () => {
 119       assertStrictEquals(
 120         new Tag().identifier,
 121         null,
 122       );
 123     });
 124
 125     it("[[Construct]] correctly sets the preferred label to a language‐tagged string", () => {
 126       assertEquals(
 127         {
 128           ...new Tag("RelationshipTag", {
 129             "@value": "Shadow, Me",
 130             "@language": "en",
 131           }).prefLabel,
 132         },
 133         { "@value": "Shadow, Me", "@language": "en" },
 134       );
 135     });
 136
 137     it("[[Construct]] throws if the tag kind is not recognized", () => {
 138       assertThrows(() => {
 139         new Tag("NotATag");
 140       });
 141     });
 142
 143     describe(".all", () => {
 144       it("[[Call]] yields all the persisted tags", () => {
 145         const tags = new Set(function* () {
 146           let i = 0;
 147           while (i++ < 5) {
 148             // Generate 5 tags and remember their identifiers.
 149             const tag = new Tag();
 150             tag.persist();
 151             yield tag.identifier;
 152           }
 153         }());
 154         for (const tag of Tag.all()) {
 155           assertStrictEquals(
 156             Object.getPrototypeOf(tag),
 157             Tag.prototype,
 158           );
 159         }
 160         assertEquals(
 161           new Set(Array.from(Tag.all(), (tag) => tag.identifier)),
 162           tags,
 163         );
 164       });
 165     });
 166
 167     describe(".constructor", () => {
 168       it("[[Get]] is `Function`", () => {
 169         assertStrictEquals(Tag.constructor, Function);
 170       });
 171     });
 172
 173     describe(".fromIRI", () => {
 174       it("[[Call]] returns the persisted tag with the given I·R·I", () => {
 175         const tag = new Tag();
 176         tag.persist();
 177         const { identifier, iri } = tag;
 178         const retrieved = Tag.fromIRI(iri);
 179         assertStrictEquals(
 180           Object.getPrototypeOf(retrieved),
 181           Tag.prototype,
 182         );
 183         assertStrictEquals(retrieved.identifier, identifier);
 184       });
 185
 186       it("[[Call]] returns null if no tag with the given I·R·I has been persisted", () => {
 187         assertStrictEquals(
 188           Tag.fromIRI(
 189             `https://${system.authorityName}/tag:${system.taggingEntity}:000-0000`,
 190           ),
 191           null,
 192         );
 193       });
 194
 195       it("[[Call]] throws if passed an invalid I·R·I", () => {
 196         assertThrows(() => {
 197           Tag.fromIRI(`bad iri`);
 198         });
 199       });
 200     });
 201
 202     describe(".fromIdentifier", () => {
 203       it("[[Call]] returns the persisted tag with the given identifier", () => {
 204         const tag = new Tag();
 205         tag.persist();
 206         const { identifier } = tag;
 207         const retrieved = Tag.fromIdentifier(identifier);
 208         assertStrictEquals(
 209           Object.getPrototypeOf(retrieved),
 210           Tag.prototype,
 211         );
 212         assertStrictEquals(retrieved.identifier, identifier);
 213       });
 214
 215       it("[[Call]] returns null if no tag with the given identifier has been persisted", () => {
 216         assertStrictEquals(Tag.fromIdentifier("000-0000"), null);
 217       });
 218
 219       it("[[Call]] throws if passed an invalid identifier", () => {
 220         assertThrows(() => {
 221           Tag.fromIdentifier(""); // wrong format
 222         });
 223         assertThrows(() => {
 224           Tag.fromIdentifier("100-0000"); // bad checksum
 225         });
 226       });
 227     });
 228
 229     describe(".fromTagURI", () => {
 230       it("[[Call]] returns the persisted tag with the given Tag U·R·I", () => {
 231         const tag = new Tag();
 232         tag.persist();
 233         const { identifier, tagURI } = tag;
 234         const retrieved = Tag.fromTagURI(tagURI);
 235         assertStrictEquals(
 236           Object.getPrototypeOf(retrieved),
 237           Tag.prototype,
 238         );
 239         assertStrictEquals(retrieved.identifier, identifier);
 240       });
 241
 242       it("[[Call]] returns null if no tag with the given Tag U·R·I has been persisted", () => {
 243         assertStrictEquals(
 244           Tag.fromTagURI(`tag:${system.taggingEntity}:`),
 245           null,
 246         );
 247         assertStrictEquals(
 248           Tag.fromTagURI(`tag:${system.taggingEntity}:000-0000`),
 249           null,
 250         );
 251       });
 252
 253       it("[[Call]] throws if passed an invalid Tag U·R·I", () => {
 254         assertThrows(() => {
 255           Tag.fromTagURI(""); // wrong format
 256         });
 257         assertThrows(() => {
 258           Tag.fromTagURI(
 259             "tag:unexample,1970-01-01:Z", // incorrect tagging entity
 260           );
 261         });
 262       });
 263     });
 264
 265     describe(".identifiers", () => {
 266       it("[[Call]] yields all the persisted identifiers", () => {
 267         const tags = new Set(function* () {
 268           let i = 0;
 269           while (i++ < 5) {
 270             // Generate 5 tags and remember their identifiers.
 271             const tag = new Tag();
 272             tag.persist();
 273             yield tag.identifier;
 274           }
 275         }());
 276         assertEquals(
 277           new Set(Tag.identifiers()),
 278           tags,
 279         );
 280       });
 281     });
 282
 283     // `.[Storage.toInstance]` is tested by `.fromIdentifier`.
 284
 285     describe("::addAltLabel", () => {
 286       it("[[Call]] does nothing if called with no arguments", () => {
 287         const tag = new Tag();
 288         tag.addAltLabel();
 289         assertEquals([...tag.altLabels()], []);
 290       });
 291
 292       it("[[Call]] adds the provided alternative labels", () => {
 293         const tag = new Tag();
 294         tag.addAltLabel(
 295           "one",
 296           { "@value": "two" },
 297           { "@value": "three", "@language": "en" },
 298         );
 299         assertEquals(
 300           Array.from(tag.altLabels(), ($) => ({ ...$ })),
 301           [
 302             { "@value": "one" },
 303             { "@value": "two" },
 304             { "@value": "three", "@language": "en" },
 305           ],
 306         );
 307       });
 308
 309       it("[[Call]] returns this", () => {
 310         const tag = new Tag();
 311         assertStrictEquals(tag.addAltLabel(), tag);
 312       });
 313     });
 314
 315     describe("::addBroaderTag", () => {
 316       it("[[Call]] does nothing if called with no arguments", () => {
 317         const tag = new Tag();
 318         tag.addBroaderTag();
 319         assertEquals([...tag.broaderTags()], []);
 320       });
 321
 322       it("[[Call]] adds the provided broader tags", () => {
 323         const broader = new Tag();
 324         broader.persist();
 325         const broader2 = new Tag();
 326         broader2.persist();
 327         const tag = new Tag();
 328         tag.addBroaderTag(broader, broader2);
 329         assertEquals(
 330           Array.from(tag.broaderTags(), ($) => $.identifier),
 331           [broader.identifier, broader2.identifier],
 332         );
 333       });
 334
 335       it("[[Call]] returns this", () => {
 336         const tag = new Tag();
 337         assertStrictEquals(tag.addBroaderTag(), tag);
 338       });
 339
 340       it("[[Call]] throws when adding a non‐persisted tag", () => {
 341         const tag = new Tag();
 342         assertThrows(() => {
 343           tag.addBroaderTag(new Tag());
 344         });
 345       });
 346
 347       it("[[Call]] throws when adding an unrecognized identifier", () => {
 348         const tag = new Tag();
 349         assertThrows(() => {
 350           tag.addBroaderTag("000-0000"); // not persisted
 351         });
 352         assertThrows(() => {
 353           tag.addBroaderTag(""); // bad format
 354         });
 355       });
 356     });
 357
 358     describe("::addHiddenLabel", () => {
 359       it("[[Call]] does nothing if called with no arguments", () => {
 360         const tag = new Tag();
 361         tag.addHiddenLabel();
 362         assertEquals([...tag.hiddenLabels()], []);
 363       });
 364
 365       it("[[Call]] adds the provided hidden labels", () => {
 366         const tag = new Tag();
 367         tag.addHiddenLabel(
 368           "one",
 369           { "@value": "two" },
 370           { "@value": "three", "@language": "en" },
 371         );
 372         assertEquals(
 373           Array.from(tag.hiddenLabels(), ($) => ({ ...$ })),
 374           [
 375             { "@value": "one" },
 376             { "@value": "two" },
 377             { "@value": "three", "@language": "en" },
 378           ],
 379         );
 380       });
 381
 382       it("[[Call]] returns this", () => {
 383         const tag = new Tag();
 384         assertStrictEquals(tag.addHiddenLabel(), tag);
 385       });
 386     });
 387
 388     describe("::addInCanonTag", () => {
 389       it("[[Call]] does nothing if called with no arguments", () => {
 390         const tag = new Tag("EntityTag");
 391         tag.addInCanonTag();
 392         assertEquals([...tag.inCanonTags()], []);
 393       });
 394
 395       it("[[Call]] adds the provided canon tags", () => {
 396         const canon = new Tag("CanonTag");
 397         canon.persist();
 398         const canon2 = new Tag("CanonTag");
 399         canon2.persist();
 400         const tag = new Tag("EntityTag");
 401         tag.addInCanonTag(canon, canon2);
 402         assertEquals(
 403           Array.from(tag.inCanonTags(), ($) => $.identifier),
 404           [canon.identifier, canon2.identifier],
 405         );
 406       });
 407
 408       it("[[Call]] returns this", () => {
 409         const tag = new Tag("EntityTag");
 410         assertStrictEquals(tag.addInCanonTag(), tag);
 411       });
 412
 413       it("[[Call]] throws when this is not a tag which can be placed in canon", () => {
 414         const canon = new Tag("CanonTag");
 415         canon.persist();
 416         assertThrows(() => {
 417           new Tag().addInCanonTag(canon);
 418         });
 419       });
 420
 421       it("[[Call]] throws when provided with a non‐canon tag", () => {
 422         const notCanon = new Tag();
 423         notCanon.persist();
 424         const tag = new Tag("EntityTag");
 425         assertThrows(() => {
 426           tag.addInCanonTag(notCanon);
 427         });
 428       });
 429
 430       it("[[Call]] throws when adding a non‐persisted tag", () => {
 431         const tag = new Tag("EntityTag");
 432         assertThrows(() => {
 433           tag.addInCanonTag(new Tag("CanonTag"));
 434         });
 435       });
 436
 437       it("[[Call]] throws when adding an unrecognized identifier", () => {
 438         const tag = new Tag("EntityTag");
 439         assertThrows(() => {
 440           tag.addInCanonTag("000-0000"); // not persisted
 441         });
 442         assertThrows(() => {
 443           tag.addInCanonTag(""); // bad format
 444         });
 445       });
 446     });
 447
 448     describe("::addInvolvesTag", () => {
 449       it("[[Call]] does nothing if called with no arguments", () => {
 450         const tag = new Tag("ConceptualTag");
 451         tag.addInvolvesTag();
 452         assertEquals([...tag.involvesTags()], []);
 453       });
 454
 455       it("[[Call]] adds the provided tags", () => {
 456         const involved = new Tag();
 457         involved.persist();
 458         const involved2 = new Tag();
 459         involved2.persist();
 460         const tag = new Tag("ConceptualTag");
 461         tag.addInvolvesTag(involved, involved2);
 462         assertEquals(
 463           Array.from(tag.involvesTags(), ($) => $.identifier),
 464           [involved.identifier, involved2.identifier],
 465         );
 466       });
 467
 468       it("[[Call]] returns this", () => {
 469         const tag = new Tag("ConceptualTag");
 470         assertStrictEquals(tag.addInvolvesTag(), tag);
 471       });
 472
 473       it("[[Call]] throws when this is not a conceptual tag", () => {
 474         const involved = new Tag();
 475         involved.persist();
 476         assertThrows(() => {
 477           new Tag().addInvolvesTag(involved);
 478         });
 479       });
 480
 481       it("[[Call]] throws when this is a relationship tag and provided with a non‐involvable tag", () => {
 482         const notInvolved = new Tag();
 483         notInvolved.persist();
 484         const tag = new Tag("RelationshipTag");
 485         assertThrows(() => {
 486           tag.addInvolvesTag(notInvolved);
 487         });
 488       });
 489
 490       it("[[Call]] throws when adding a non‐persisted tag", () => {
 491         const tag = new Tag("ConceptualTag");
 492         assertThrows(() => {
 493           tag.addInvolvesTag(new Tag());
 494         });
 495       });
 496
 497       it("[[Call]] throws when adding an unrecognized identifier", () => {
 498         const tag = new Tag("ConceptualTag");
 499         assertThrows(() => {
 500           tag.addInvolvesTag("000-0000"); // not persisted
 501         });
 502         assertThrows(() => {
 503           tag.addInvolvesTag(""); // bad format
 504         });
 505       });
 506     });
 507
 508     // `::altLabels` is tested by `::addAltLabel`.
 509
 510     describe("::authorityName", () => {
 511       it("[[Get]] returns the authority name of the tag system", () => {
 512         assertStrictEquals(
 513           new Tag().authorityName,
 514           system.authorityName,
 515         );
 516       });
 517     });
 518
 519     // `::broaderTags` is tested by `::addBroaderTag`.
 520
 521     describe("::broaderTransitiveTags", () => {
 522       it("[[Call]] returns broader tags transitively", () => {
 523         const superBroad = new Tag();
 524         superBroad.persist();
 525         const broad = new Tag();
 526         broad.addBroaderTag(superBroad);
 527         broad.persist();
 528         const tag = new Tag();
 529         tag.addBroaderTag(broad);
 530         assertEquals(
 531           Array.from(tag.broaderTransitiveTags(), ($) => $.identifier),
 532           [broad.identifier, superBroad.identifier],
 533         );
 534       });
 535
 536       it("[[Call]] cannot recurse infinitely", () => {
 537         const tag = new Tag();
 538         tag.persist();
 539         const broad = new Tag();
 540         broad.addBroaderTag(tag);
 541         broad.persist();
 542         tag.addBroaderTag(broad);
 543         tag.persist();
 544         assertEquals(
 545           Array.from(tag.broaderTransitiveTags(), ($) => $.identifier),
 546           [broad.identifier, tag.identifier],
 547         );
 548       });
 549     });
 550
 551     describe("::deleteAltLabel", () => {
 552       it("[[Call]] does nothing if called with no arguments", () => {
 553         const tag = new Tag();
 554         tag.addAltLabel("etaoin");
 555         tag.deleteAltLabel();
 556         assertEquals(
 557           Array.from(tag.altLabels(), ($) => ({ ...$ })),
 558           [{ "@value": "etaoin" }],
 559         );
 560       });
 561
 562       it("[[Call]] deletes only the provided hidden labels", () => {
 563         const tag = new Tag();
 564         tag.addAltLabel(
 565           "one",
 566           "two",
 567           { "@value": "three", "@language": "en" },
 568           "four",
 569         );
 570         tag.deleteAltLabel(
 571           "one",
 572           { "@value": "two" },
 573           { "@value": "three", "@language": "en" },
 574           { "@value": "four", "@language": "en" },
 575         );
 576         assertEquals(
 577           Array.from(tag.altLabels(), ($) => ({ ...$ })),
 578           [{ "@value": "four" }],
 579         );
 580       });
 581
 582       it("[[Call]] returns this", () => {
 583         const tag = new Tag();
 584         assertStrictEquals(tag.deleteAltLabel(), tag);
 585       });
 586     });
 587
 588     describe("::deleteBroaderTag", () => {
 589       it("[[Call]] does nothing if called with no arguments", () => {
 590         const broader = new Tag();
 591         broader.persist();
 592         const tag = new Tag();
 593         tag.addBroaderTag(broader);
 594         tag.deleteBroaderTag();
 595         assertEquals(
 596           Array.from(tag.broaderTags(), ($) => $.identifier),
 597           [broader.identifier],
 598         );
 599       });
 600
 601       it("[[Call]] deletes only the provided broader tags", () => {
 602         const superBroader = new Tag();
 603         superBroader.persist();
 604         const broader = new Tag();
 605         broader.addBroaderTag(superBroader);
 606         broader.persist();
 607         const broader2 = new Tag();
 608         broader2.addBroaderTag(superBroader);
 609         broader2.persist();
 610         const tag = new Tag();
 611         tag.addBroaderTag(broader, broader2);
 612         tag.deleteBroaderTag(broader, superBroader, "000-0000", "");
 613         assertEquals(
 614           Array.from(tag.broaderTags(), ($) => $.identifier),
 615           [broader2.identifier],
 616         );
 617       });
 618
 619       it("[[Call]] returns this", () => {
 620         const tag = new Tag();
 621         assertStrictEquals(tag.deleteBroaderTag(), tag);
 622       });
 623     });
 624
 625     describe("::deleteHiddenLabel", () => {
 626       it("[[Call]] does nothing if called with no arguments", () => {
 627         const tag = new Tag();
 628         tag.addHiddenLabel("etaoin");
 629         tag.deleteHiddenLabel();
 630         assertEquals(
 631           Array.from(tag.hiddenLabels(), ($) => ({ ...$ })),
 632           [{ "@value": "etaoin" }],
 633         );
 634       });
 635
 636       it("[[Call]] deletes only the provided alternative labels", () => {
 637         const tag = new Tag();
 638         tag.addHiddenLabel(
 639           "one",
 640           "two",
 641           { "@value": "three", "@language": "en" },
 642           "four",
 643         );
 644         tag.deleteHiddenLabel(
 645           "one",
 646           { "@value": "two" },
 647           { "@value": "three", "@language": "en" },
 648           { "@value": "four", "@language": "en" },
 649         );
 650         assertEquals(
 651           Array.from(tag.hiddenLabels(), ($) => ({ ...$ })),
 652           [{ "@value": "four" }],
 653         );
 654       });
 655
 656       it("[[Call]] returns this", () => {
 657         const tag = new Tag();
 658         assertStrictEquals(tag.deleteHiddenLabel(), tag);
 659       });
 660     });
 661
 662     describe("::deleteInCanonTag", () => {
 663       it("[[Call]] does nothing if called with no arguments", () => {
 664         const canon = new Tag("CanonTag");
 665         canon.persist();
 666         const tag = new Tag("EntityTag");
 667         tag.addInCanonTag(canon);
 668         tag.deleteInCanonTag();
 669         assertEquals(
 670           Array.from(tag.inCanonTags(), ($) => $.identifier),
 671           [canon.identifier],
 672         );
 673       });
 674
 675       it("[[Call]] deletes only the provided canon tags", () => {
 676         const canon = new Tag("CanonTag");
 677         canon.persist();
 678         const canon2 = new Tag("CanonTag");
 679         canon2.persist();
 680         const tag = new Tag("EntityTag");
 681         tag.addInCanonTag(canon, canon2);
 682         tag.deleteInCanonTag(canon, "000-0000", "");
 683         assertEquals(
 684           Array.from(tag.inCanonTags(), ($) => $.identifier),
 685           [canon2.identifier],
 686         );
 687       });
 688
 689       it("[[Call]] returns this", () => {
 690         const tag = new Tag("EntityTag");
 691         assertStrictEquals(tag.deleteInCanonTag(), tag);
 692       });
 693     });
 694
 695     describe("::deleteInvolvesTag", () => {
 696       it("[[Call]] does nothing if called with no arguments", () => {
 697         const involved = new Tag();
 698         involved.persist();
 699         const tag = new Tag("ConceptualTag");
 700         tag.addInvolvesTag(involved);
 701         tag.deleteInvolvesTag();
 702         assertEquals(
 703           Array.from(tag.involvesTags(), ($) => $.identifier),
 704           [involved.identifier],
 705         );
 706       });
 707
 708       it("[[Call]] deletes only the provided involved tags", () => {
 709         const character = new Tag("CharacterTag");
 710         character.persist();
 711         const involved = new Tag("RelationshipTag");
 712         involved.addInvolvesTag(character);
 713         involved.persist();
 714         const involved2 = new Tag("RelationshipTag");
 715         involved2.addInvolvesTag(character);
 716         involved2.persist();
 717         const tag = new Tag("RelationshipTag");
 718         tag.addInvolvesTag(involved, involved2);
 719         tag.deleteInvolvesTag(involved, character, "000-0000", "");
 720         assertEquals(
 721           Array.from(tag.involvesTags(), ($) => $.identifier),
 722           [involved2.identifier],
 723         );
 724       });
 725
 726       it("[[Call]] returns this", () => {
 727         const tag = new Tag("ConceptualTag");
 728         assertStrictEquals(tag.deleteInvolvesTag(), tag);
 729       });
 730     });
 731
 732     describe("::hasInCanonTags", () => {
 733       it("[[Call]] yields the persisted tags which have this tag in canon", () => {
 734         const canon = new Tag("CanonTag");
 735         canon.persist();
 736         const entity = new Tag("EntityTag");
 737         entity.addInCanonTag(canon);
 738         entity.persist();
 739         const entity2 = new Tag("EntityTag");
 740         entity2.addInCanonTag(canon);
 741         entity2.persist();
 742         const tag = Tag.fromIdentifier(canon.identifier); // reload
 743         assertEquals(
 744           Array.from(tag.hasInCanonTags(), ($) => $.identifier),
 745           [entity.identifier, entity2.identifier],
 746         );
 747       });
 748     });
 749
 750     // `::hiddenLabels` is tested by `::addHiddenLabel`.
 751
 752     // `::identifier` is tested by a `.fromIdentifier`.
 753
 754     // `::inCanonTags` is tested by `::addInCanonTag`.
 755
 756     describe("::involvedInTags", () => {
 757       it("[[Call]] yields the persisted tags which involve this tag", () => {
 758         const involved = new Tag();
 759         involved.persist();
 760         const conceptual = new Tag("ConceptualTag");
 761         conceptual.addInvolvesTag(involved);
 762         conceptual.persist();
 763         const conceptual2 = new Tag("ConceptualTag");
 764         conceptual2.addInvolvesTag(involved);
 765         conceptual2.persist();
 766         const tag = Tag.fromIdentifier(involved.identifier); // reload
 767         assertEquals(
 768           Array.from(tag.involvedInTags(), ($) => $.identifier),
 769           [conceptual.identifier, conceptual2.identifier],
 770         );
 771       });
 772     });
 773
 774     // `::involvesTags` is tested by `::addInvolvesTag`.
 775
 776     // `::iri` is tested by a `.fromIRI`.
 777
 778     // `::iriSpace` is tested by a `.fromIRI`.
 779
 780     // `::kind` is tested by the constructor.
 781
 782     describe("::narrowerTags", () => {
 783       it("[[Call]] yields the persisted tags which are narrower than this tag", () => {
 784         const broader = new Tag();
 785         broader.persist();
 786         const narrower = new Tag();
 787         narrower.addBroaderTag(broader);
 788         narrower.persist();
 789         const narrower2 = new Tag();
 790         narrower2.addBroaderTag(broader);
 791         narrower2.persist();
 792         const tag = Tag.fromIdentifier(broader.identifier); // reload
 793         assertEquals(
 794           Array.from(tag.narrowerTags(), ($) => $.identifier),
 795           [narrower.identifier, narrower2.identifier],
 796         );
 797       });
 798     });
 799
 800     describe("::narrowerTransitiveTags", () => {
 801       it("[[Call]] returns narrower tags transitively", () => {
 802         const broad = new Tag();
 803         broad.persist();
 804         const narrow = new Tag();
 805         narrow.addBroaderTag(broad);
 806         narrow.persist();
 807         const superNarrow = new Tag();
 808         superNarrow.addBroaderTag(narrow);
 809         superNarrow.persist();
 810         const tag = Tag.fromIdentifier(broad.identifier); // reload
 811         assertEquals(
 812           Array.from(
 813             tag.narrowerTransitiveTags(),
 814             ($) => $.identifier,
 815           ),
 816           [narrow.identifier, superNarrow.identifier],
 817         );
 818       });
 819
 820       it("[[Call]] cannot recurse infinitely", () => {
 821         const tag = new Tag();
 822         tag.persist();
 823         const broad = new Tag();
 824         broad.addBroaderTag(tag);
 825         broad.persist();
 826         tag.addBroaderTag(broad);
 827         tag.persist();
 828         assertEquals(
 829           Array.from(tag.broaderTransitiveTags(), ($) => $.identifier),
 830           [broad.identifier, tag.identifier],
 831         );
 832       });
 833     });
 834
 835     describe("::persist", () => {
 836       it("[[Call]] returns an object with expected properties if there were changes", () => {
 837         const tag = new Tag();
 838         const activity = tag.persist();
 839         assertObjectMatch(
 840           activity,
 841           {
 842             "@context":
 843               "https://ns.1024.gdn/Tagging/discovery.context.jsonld",
 844             context: system.iri,
 845             object: tag.iri,
 846           },
 847         );
 848         assertArrayIncludes(activity["@type"], ["TagActivity"]);
 849         assert("endTime" in activity);
 850       });
 851
 852       it("[[Call]] returns a Create activity with a type predicate for new objects", () => {
 853         const activity = new Tag().persist();
 854         assertEquals(activity["@type"], ["TagActivity", "Create"]);
 855         assertArrayIncludes(activity.states, [{
 856           predicate: "a",
 857           object: "Tag",
 858         }]);
 859       });
 860
 861       it("[[Call]] returns an Update activity for old objects", () => {
 862         const tag = new Tag();
 863         tag.persist();
 864         tag.prefLabel = "etaoin";
 865         const activity = tag.persist();
 866         assertEquals(activity["@type"], ["TagActivity", "Update"]);
 867       });
 868
 869       it("[[Call]] states and unstates changes", () => {
 870         const broader1 = new Tag();
 871         broader1.persist();
 872         const broader2 = new Tag();
 873         broader2.persist();
 874         const tag = new Tag();
 875         tag.addBroaderTag(broader1);
 876         tag.persist();
 877         tag.prefLabel = "etaoin";
 878         tag.deleteBroaderTag(broader1);
 879         tag.addBroaderTag(broader2);
 880         const activity = tag.persist();
 881         assertObjectMatch(activity, {
 882           unstates: [
 883             { predicate: "prefLabel", object: { "@value": "" } },
 884             { predicate: "broader", object: broader1.iri },
 885           ],
 886           states: [
 887             { predicate: "prefLabel", object: { "@value": "etaoin" } },
 888             { predicate: "broader", object: broader2.iri },
 889           ],
 890         });
 891       });
 892
 893       it("[[Call]] doesn’t state if there are no additions", () => {
 894         const tag = new Tag();
 895         tag.addAltLabel("etaoin");
 896         tag.persist();
 897         tag.deleteAltLabel("etaoin");
 898         const activity = tag.persist();
 899         assertFalse("state" in activity);
 900       });
 901
 902       it("[[Call]] doesn’t unstate if there are no removals", () => {
 903         const tag = new Tag();
 904         tag.persist();
 905         tag.addAltLabel("etaoin");
 906         const activity = tag.persist();
 907         assertFalse("unstate" in activity);
 908       });
 909
 910       it("[[Call]] returns null if no meaningful changes were made", () => {
 911         const tag = new Tag();
 912         tag.persist();
 913         const activity = tag.persist();
 914         assertStrictEquals(activity, null);
 915       });
 916
 917       it("[[Call]] returns undefined for a silent persist", () => {
 918         const broader = new Tag();
 919         broader.persist();
 920         const tag = new Tag();
 921         tag.prefLabel = "etaoin";
 922         tag.addBroaderTag(broader);
 923         assertStrictEquals(tag.persist(true), undefined);
 924       });
 925     });
 926
 927     describe("::prefLabel", () => {
 928       it("[[Set]] sets the preferred label", () => {
 929         const tag = new Tag();
 930         tag.prefLabel = "one";
 931         assertEquals({ ...tag.prefLabel }, { "@value": "one" });
 932         tag.prefLabel = { "@value": "two" };
 933         assertEquals({ ...tag.prefLabel }, { "@value": "two" });
 934         tag.prefLabel = { "@value": "three", "@language": "en" };
 935         assertEquals(
 936           { ...tag.prefLabel },
 937           { "@value": "three", "@language": "en" },
 938         );
 939       });
 940     });
 941
 942     // `::tagURI` is tested by a `.fromTagURI`.
 943
 944     describe("::taggingEntity", () => {
 945       it("[[Get]] returns the tagging entity of the tag system", () => {
 946         assertStrictEquals(
 947           new Tag().taggingEntity,
 948           system.taggingEntity,
 949         );
 950       });
 951     });
 952
 953     describe("::toString", () => {
 954       it("[[Get]] returns the string value of the preferred label", () => {
 955         const tag = new Tag();
 956         tag.prefLabel = { "@value": "etaoin", "@language": "zxx" };
 957         assertStrictEquals(tag.toString(), "etaoin");
 958       });
 959     });
 960
 961     // `::[Storage.toObject]` is tested by `::persist`.
 962   });
 963
 964   describe("::authorityName", () => {
 965     it("[[Get]] returns the authority name", () => {
 966       const system = new TagSystem("etaoin.example", "1972-12-31");
 967       assertStrictEquals(system.authorityName, "etaoin.example");
 968     });
 969   });
 970
 971   describe("::authorityName", () => {
 972     it("[[Get]] returns the date", () => {
 973       const system = new TagSystem("etaoin.example", "1972-12-31");
 974       assertStrictEquals(system.date, "1972-12-31");
 975     });
 976   });
 977
 978   describe("::identifiers", () => {
 979     it("[[Get]] yields the extant entities", () => {
 980       const system = new TagSystem("etaoin.example", "1972-12-31");
 981       const tags = new Set(function* () {
 982         let i = 0;
 983         while (i++ < 5) {
 984           // Generate 5 tags and remember their identifiers.
 985           const tag = new system.Tag();
 986           tag.persist();
 987           yield tag.identifier;
 988         }
 989       }());
 990       assertEquals(
 991         new Set(Array.from(system.entities(), ($) => $.identifier)),
 992         tags,
 993       );
 994     });
 995   });
 996
 997   describe("::identifier", () => {
 998     it("[[Get]] returns the identifier", () => {
 999       const system = new TagSystem("etaoin.example", "1972-12-31");
1000       assertStrictEquals(system.identifier, "");
1001       const system2 = new TagSystem(
1002         "etaoin.example",
1003         "1972-12-31",
1004         "etaoin",
1005       );
1006       assertStrictEquals(system2.identifier, "etaoin");
1007     });
1008   });
1009
1010   describe("::identifiers", () => {
1011     it("[[Get]] yields the identifiers in use", () => {
1012       const system = new TagSystem("etaoin.example", "1972-12-31");
1013       const tags = new Set(function* () {
1014         let i = 0;
1015         while (i++ < 5) {
1016           // Generate 5 tags and remember their identifiers.
1017           const tag = new system.Tag();
1018           tag.persist();
1019           yield tag.identifier;
1020         }
1021       }());
1022       assertEquals(new Set(system.identifiers()), tags);
1023     });
1024   });
1025
1026   describe("::iri", () => {
1027     it("[[Get]] returns the I·R·I", () => {
1028       const system = new TagSystem("etaoin.example", "1972-12-31");
1029       assertStrictEquals(
1030         system.iri,
1031         "https://etaoin.example/tag:etaoin.example,1972-12-31:",
1032       );
1033       const system2 = new TagSystem(
1034         "etaoin.example",
1035         "1972-12-31",
1036         "etaoin",
1037       );
1038       assertStrictEquals(
1039         system2.iri,
1040         "https://etaoin.example/tag:etaoin.example,1972-12-31:etaoin",
1041       );
1042     });
1043   });
1044
1045   describe("::iriSpace", () => {
1046     it("[[Get]] returns the I·R·I space", () => {
1047       const system = new TagSystem("etaoin.example", "1972-12-31");
1048       assertStrictEquals(
1049         system.iriSpace,
1050         "https://etaoin.example/tag:etaoin.example,1972-12-31:",
1051       );
1052       const system2 = new TagSystem(
1053         "etaoin.example",
1054         "1972-12-31",
1055         "etaoin",
1056       );
1057       assertStrictEquals(
1058         system2.iriSpace,
1059         "https://etaoin.example/tag:etaoin.example,1972-12-31:",
1060       );
1061     });
1062   });
1063
1064   describe("::tagURI", () => {
1065     it("[[Get]] returns the Tag U·R·I", () => {
1066       const system = new TagSystem("etaoin.example", "1972-12-31");
1067       assertStrictEquals(
1068         system.tagURI,
1069         "tag:etaoin.example,1972-12-31:",
1070       );
1071       const system2 = new TagSystem(
1072         "etaoin.example",
1073         "1972-12-31",
1074         "etaoin",
1075       );
1076       assertStrictEquals(
1077         system2.tagURI,
1078         "tag:etaoin.example,1972-12-31:etaoin",
1079       );
1080     });
1081   });
1082
1083   describe("::taggingEntity", () => {
1084     it("[[Get]] returns the tagging entity", () => {
1085       const system = new TagSystem("etaoin.example", "1972-12-31");
1086       assertStrictEquals(
1087         system.taggingEntity,
1088         "etaoin.example,1972-12-31",
1089       );
1090     });
1091   });
1092 });