fix(ivy): support ICUs without "other" cases (#34042)

Prior to this commit, there was a runtime check in i18n logic to make sure "other" case is always present in an ICU. That was not a requirement in View Engine, so ICUs that previously worked may produce errors. This commit removes that restriction and adds support for ICUs without "other" cases.

PR Close #34042

Author: AndrewKushnir

packages/core/src/render3/i18n.ts

@@ -12,7 +12,7 @@ import {SRCSET_ATTRS, URI_ATTRS, VALID_ATTRS, VALID_ELEMENTS, getTemplateContent
 import {InertBodyHelper} from '../sanitization/inert_body';
 import {_sanitizeUrl, sanitizeSrcset} from '../sanitization/url_sanitizer';
 import {addAllToArray} from '../util/array_utils';
-import {assertDataInRange, assertDefined, assertEqual, assertGreaterThan} from '../util/assert';
+import {assertDataInRange, assertDefined, assertEqual} from '../util/assert';
 
 import {bindingUpdated} from './bindings';
 import {attachPatchData} from './context_discovery';
@@ -190,7 +190,6 @@ function parseICUBlock(pattern: string): IcuExpression {
     }
   }
 
-  assertGreaterThan(cases.indexOf('other'), -1, 'Missing key "other" in ICU statement.');
   // TODO(ocombe): support ICU expressions in attributes, see #21615
   return {type: icuType, mainBinding: mainBinding, cases, values};
 }
@@ -895,18 +894,21 @@ function readUpdateOpCodes(
                 // Update the active caseIndex
                 const caseIndex = getCaseIndex(tIcu, value);
                 icuTNode.activeCaseIndex = caseIndex !== -1 ? caseIndex : null;
-
-                // Add the nodes for the new case
-                readCreateOpCodes(-1, tIcu.create[caseIndex], viewData);
-                caseCreated = true;
+                if (caseIndex > -1) {
+                  // Add the nodes for the new case
+                  readCreateOpCodes(-1, tIcu.create[caseIndex], viewData);
+                  caseCreated = true;
+                }
                 break;
               case I18nUpdateOpCode.IcuUpdate:
                 tIcuIndex = updateOpCodes[++j] as number;
                 tIcu = icus ![tIcuIndex];
                 icuTNode = getTNode(nodeIndex, viewData) as TIcuContainerNode;
-                readUpdateOpCodes(
-                    tIcu.update[icuTNode.activeCaseIndex !], icus, bindingsStartIndex, changeMask,
-                    viewData, caseCreated);
+                if (icuTNode.activeCaseIndex !== null) {
+                  readUpdateOpCodes(
+                      tIcu.update[icuTNode.activeCaseIndex], icus, bindingsStartIndex, changeMask,
+                      viewData, caseCreated);
+                }
                 break;
             }
           }

packages/core/test/acceptance/i18n_spec.ts

@@ -1094,6 +1094,110 @@ onlyInIvy('Ivy i18n logic').describe('runtime i18n', () => {
       fixture.detectChanges();
       expect(fixture.debugElement.nativeElement.innerHTML).toContain('plus d\'un');
     });
+
+    it('should support ICUs without "other" cases', () => {
+      loadTranslations({
+        idA: '{VAR_SELECT, select, 1 {un (select)} 2 {deux (select)}}',
+        idB: '{VAR_PLURAL, plural, =1 {un (plural)} =2 {deux (plural)}}',
+      });
+
+      @Component({
+        selector: 'app',
+        template: `
+          <div i18n="@@idA">{count, select, 1 {one (select)} 2 {two (select)}}</div> -
+          <div i18n="@@idB">{count, plural, =1 {one (plural)} =2 {two (plural)}}</div>
+        `
+      })
+      class AppComponent {
+        count = 1;
+      }
+
+      TestBed.configureTestingModule({declarations: [AppComponent]});
+
+      const fixture = TestBed.createComponent(AppComponent);
+      fixture.detectChanges();
+      expect(fixture.nativeElement.textContent).toBe('un (select) - un (plural)');
+
+      fixture.componentInstance.count = 3;
+      fixture.detectChanges();
+      // there is no ICU case for count=3
+      expect(fixture.nativeElement.textContent.trim()).toBe('-');
+
+      fixture.componentInstance.count = 4;
+      fixture.detectChanges();
+      // there is no ICU case for count=4, making sure content is still empty
+      expect(fixture.nativeElement.textContent.trim()).toBe('-');
+
+      fixture.componentInstance.count = 2;
+      fixture.detectChanges();
+      // check switching to an existing case after processing an ICU without matching case
+      expect(fixture.nativeElement.textContent.trim()).toBe('deux (select) - deux (plural)');
+
+      fixture.componentInstance.count = 1;
+      fixture.detectChanges();
+      // check that we can go back to the first ICU case
+      expect(fixture.nativeElement.textContent).toBe('un (select) - un (plural)');
+    });
+
+    it('should support nested ICUs without "other" cases', () => {
+      loadTranslations({
+        idA: '{VAR_SELECT_1, select, A {{VAR_SELECT, select, ' +
+            '1 {un (select)} 2 {deux (select)}}} other {}}',
+        idB: '{VAR_SELECT, select, A {{VAR_PLURAL, plural, ' +
+            '=1 {un (plural)} =2 {deux (plural)}}} other {}}',
+      });
+
+      @Component({
+        selector: 'app',
+        template: `
+          <div i18n="@@idA">{
+            type, select,
+              A {{count, select, 1 {one (select)} 2 {two (select)}}}
+              other {}
+          }</div> -
+          <div i18n="@@idB">{
+            type, select,
+              A {{count, plural, =1 {one (plural)} =2 {two (plural)}}}
+              other {}
+          }</div>
+        `
+      })
+      class AppComponent {
+        type = 'A';
+        count = 1;
+      }
+
+      TestBed.configureTestingModule({declarations: [AppComponent]});
+
+      const fixture = TestBed.createComponent(AppComponent);
+      fixture.detectChanges();
+      expect(fixture.nativeElement.textContent).toBe('un (select) - un (plural)');
+
+      fixture.componentInstance.count = 3;
+      fixture.detectChanges();
+      // there is no case for count=3 in nested ICU
+      expect(fixture.nativeElement.textContent.trim()).toBe('-');
+
+      fixture.componentInstance.count = 4;
+      fixture.detectChanges();
+      // there is no case for count=4 in nested ICU, making sure content is still empty
+      expect(fixture.nativeElement.textContent.trim()).toBe('-');
+
+      fixture.componentInstance.count = 2;
+      fixture.detectChanges();
+      // check switching to an existing case after processing nested ICU without matching case
+      expect(fixture.nativeElement.textContent.trim()).toBe('deux (select) - deux (plural)');
+
+      fixture.componentInstance.count = 1;
+      fixture.detectChanges();
+      // check that we can go back to the first case in nested ICU
+      expect(fixture.nativeElement.textContent).toBe('un (select) - un (plural)');
+
+      fixture.componentInstance.type = 'B';
+      fixture.detectChanges();
+      // check that nested ICU is removed if root ICU case has changed
+      expect(fixture.nativeElement.textContent.trim()).toBe('-');
+    });
   });
 
   describe('should support attributes', () => {