Navigation: Start writing unit tests for TopBarTracker

And fix some bugs that they caught.

I still need to add more tests

package.json

@@ -9,6 +9,7 @@
       "js": true,
       "ts": "module"
     },
+    "timeout": "30s",
     "files": [
       "src/**/*.test.*"
     ],

src/view-model/navigation/top-bar-model.test.ts

@@ -1,7 +1,13 @@
-import test from 'ava'
-import { ScrollViewModel } from '../scroll-view-model.ts'
+import test, { ExecutionContext } from 'ava'
+import {
+  RenderedEntry,
+  RenderedLineInfo,
+  ScrollViewModel,
+} from '../scroll-view-model.ts'
 import { LeiningGenerator } from '../../calendar-model/generator.ts'
 import { UserSettings } from '../../calendar-model/user-settings.ts'
+import { fetchPages, renderLine } from '../test-utils.ts'
+import { Link, TopBarTracker } from './top-bar-model.ts'
 
 const testSettings: UserSettings = {
   ashkenazi: true,
@@ -11,11 +17,138 @@ const testSettings: UserSettings = {
 
 const generator = new LeiningGenerator(testSettings)
 
-test('renders for בראשית', (t) => {
-  const viewModel = ScrollViewModel.forId(
-    generator,
-    '2024-10-26:shacharis,main'
+const cachedTracker = new TopBarTracker()
+
+let viewModel: ScrollViewModel | null = null
+let pages: RenderedEntry[] = []
+
+async function createModel(
+  id: string,
+  fetch: Parameters<typeof fetchPages>[1]
+) {
+  viewModel = ScrollViewModel.forId(generator, id)
+  pages = await fetchPages(viewModel, fetch)
+}
+
+test.afterEach('reset state', () => {
+  viewModel = null
+  pages = []
+})
+
+test.serial('renders for the beginning of בראשית', async (t) => {
+  await createModel('2024-10-26:shacharis,main', {
+    count: 5,
+    fetchPreviousPages: false,
+  })
+
+  t.snapshot(
+    renderResult(t, {
+      first: firstLine(pages[0]),
+      center: null,
+      last: firstLine(pages[1]),
+    })
+  )
+})
+
+test.serial('renders for שמחת תורה', async (t) => {
+  await createModel('2024-10-25:shacharis,main', {
+    count: 5,
+    fetchPreviousPages: false,
+  })
+
+  t.snapshot(
+    renderResult(t, {
+      first: firstLine(pages[0]),
+      center: null,
+      last: firstLine(pages[1]),
+    })
+  )
+})
+
+test.serial('שקלים / ראש חודש as פרשה', async (t) => {
+  await createModel('2025-03-01:shacharis,main', {
+    count: 5,
+    fetchPreviousPages: false,
+  })
+
+  t.snapshot(
+    renderResult(t, {
+      first: getLine(
+        'וַיְדַבֵּ֥ר יְהֹוָ֖ה אֶל־מֹשֶׁ֥ה לֵּאמֹֽר׃ דַּבֵּר֙ אֶל־בְּנֵ֣י יִשְׂרָאֵ֔ל'
+      ),
+      center: null,
+      last: getLine(
+        'זָהָ֣ב טָה֑וֹר אַמָּתַ֤יִם וָחֵ֙צִי֙ אׇרְכָּ֔הּ וְאַמָּ֥ה וָחֵ֖צִי רׇחְבָּֽהּ׃'
+      ),
+    })
   )
-  // TODO: Snapshot
-  t.is(viewModel, viewModel)
 })
+
+test.serial('renders for חול המועד סוכות', async (t) => {
+  await createModel('2024-10-22:shacharis,main', {
+    count: 5,
+    fetchPreviousPages: false,
+  })
+
+  t.snapshot(
+    renderResult(t, {
+      first: getLine(
+        'הַחֲמִישִׁ֛י פָּרִ֥ים תִּשְׁעָ֖ה אֵילִ֣ם שְׁנָ֑יִם כְּבָשִׂ֧ים בְּנֵֽי'
+      ),
+      center: getLine(
+        'שְׁמֹנָ֖ה אֵילִ֣ם שְׁנָ֑יִם כְּבָשִׂ֧ים בְּנֵי־שָׁנָ֛ה אַרְבָּעָ֥ה עָשָׂ֖ר'
+      ),
+      last: getLine(
+        'וּשְׂעִ֥יר חַטָּ֖את אֶחָ֑ד מִלְּבַד֙ עֹלַ֣ת הַתָּמִ֔יד מִנְחָתָ֖הּ'
+      ),
+    })
+  )
+})
+
+function renderResult(
+  t: ExecutionContext,
+  lines: Parameters<TopBarTracker['setLine']>[1]
+) {
+  if (!viewModel) throw new Error('Must create viewModel first')
+  const cachedResult = cachedTracker.setLine(viewModel, lines)
+  const freshResult = new TopBarTracker().setLine(viewModel, lines)
+  t.deepEqual(cachedResult, freshResult)
+  return {
+    aliyahRange: cachedResult.aliyahRange,
+    currentRun: cachedResult.currentRun?.id,
+    previousLink: renderLink(cachedResult.previousLink),
+    nextLink: renderLink(cachedResult.nextLink),
+    relatedRuns: cachedResult.relatedRuns.map(renderLink),
+  }
+}
+
+function renderLink(link: Link | null) {
+  if (!link) return link
+  return {
+    targetRun: link.targetRun.id,
+    label: link.label,
+  }
+}
+
+function firstLine(page: RenderedEntry) {
+  if (page.type !== 'page') throw new Error('Must be a page')
+  return page.lines[0]
+}
+
+/** Finds the single line containing the specified text. */
+function getLine(text: string): RenderedLineInfo {
+  if (!viewModel) throw new Error('Must create viewModel first')
+  const results = pages.flatMap((p) =>
+    p.type === 'message'
+      ? []
+      : p.lines.filter((line) => renderLine(line).includes(text))
+  )
+
+  if (results.length !== 1)
+    throw new Error(
+      `Found ${results.length} lines:
+    
+${results.map(renderLine).join('\n')}`.trim()
+    )
+  return results[0]
+}

src/view-model/navigation/top-bar-model.test.ts.md

@@ -0,0 +1,135 @@
+# Snapshot report for `src/view-model/navigation/top-bar-model.test.ts`
+
+The actual snapshot is saved in `top-bar-model.test.ts.snap`.
+
+Generated by [AVA](https://avajs.dev).
+
+## renders for the beginning of בראשית
+
+> Snapshot 1
+
+    {
+      aliyahRange: [
+        'ראשון',
+      ],
+      currentRun: '2024-10-26:shacharis,main',
+      nextLink: {
+        label: 'ראש חודש חשון שחרית',
+        targetRun: '2024-11-01:shacharis,main',
+      },
+      previousLink: {
+        label: 'שמחת תורה שחרית',
+        targetRun: '2024-10-25:shacharis,main',
+      },
+      relatedRuns: [
+        {
+          label: 'פרשת בראשית',
+          targetRun: '2024-10-26:shacharis,main',
+        },
+        {
+          label: 'הפטרה',
+          targetRun: '2024-10-26:shacharis,haftara',
+        },
+      ],
+    }
+
+## renders for שמחת תורה
+
+> Snapshot 1
+
+    {
+      aliyahRange: [
+        'רביעי',
+      ],
+      currentRun: '2024-10-25:shacharis,main',
+      nextLink: {
+        label: 'פרשת בראשית שחרית',
+        targetRun: '2024-10-26:shacharis,main',
+      },
+      previousLink: {
+        label: 'שמיני עצרת מעריב',
+        targetRun: '2024-10-24:maariv,main',
+      },
+      relatedRuns: [
+        {
+          label: 'שמחת תורה',
+          targetRun: '2024-10-25:shacharis,main',
+        },
+        {
+          label: 'חתן בראשית',
+          targetRun: '2024-10-25:shacharis,last-aliyah',
+        },
+        {
+          label: 'מפטיר',
+          targetRun: '2024-10-25:shacharis,maftir',
+        },
+        {
+          label: 'הפטרה',
+          targetRun: '2024-10-25:shacharis,haftara',
+        },
+      ],
+    }
+
+## שקלים / ראש חודש as פרשה
+
+> Snapshot 1
+
+    {
+      aliyahRange: [
+        'ראשון',
+        'שני',
+      ],
+      currentRun: '2025-03-01:shacharis,main',
+      nextLink: {
+        label: 'פרשת תצוה שחרית',
+        targetRun: '2025-03-08:shacharis,main',
+      },
+      previousLink: {
+        label: 'ראש חודש אדר שחרית',
+        targetRun: '2025-02-28:shacharis,main',
+      },
+      relatedRuns: [
+        {
+          label: 'פרשת תרומה',
+          targetRun: '2025-03-01:shacharis,main',
+        },
+        {
+          label: 'שביעי',
+          targetRun: '2025-03-01:shacharis,last-aliyah',
+        },
+        {
+          label: 'מפטיר',
+          targetRun: '2025-03-01:shacharis,maftir',
+        },
+        {
+          label: 'הפטרה',
+          targetRun: '2025-03-01:shacharis,haftara',
+        },
+      ],
+    }
+
+## renders for חול המועד סוכות
+
+> Snapshot 1
+
+    {
+      aliyahRange: [
+        'ראשון',
+        'שלישי',
+      ],
+      currentRun: '2024-10-22:shacharis,main',
+      nextLink: {
+        label: 'סוכות ז׳ (הושענא רבה) שחרית',
+        targetRun: '2024-10-23:shacharis,main',
+      },
+      previousLink: {
+        label: 'סוכות חול המועד יום ג׳ שחרית',
+        targetRun: '2024-10-21:shacharis,main',
+      },
+      relatedRuns: [
+        {
+          label: 'סוכות חול המועד יום ד׳',
+          targetRun: '2024-10-22:shacharis,main',
+        },
+      ],
+    }

src/view-model/navigation/top-bar-model.ts

@@ -2,9 +2,9 @@ import {
   LeiningAliyah,
   LeiningInstance,
   LeiningRun,
-} from '../../calendar-model/model-types'
-import { aliyahName } from '../aliyah-labeller'
-import { RenderedLineInfo, ScrollViewModel } from '../scroll-view-model'
+} from '../../calendar-model/model-types.ts'
+import { aliyahName } from '../aliyah-labeller.ts'
+import { RenderedLineInfo, ScrollViewModel } from '../scroll-view-model.ts'
 
 /** The information and link targets displayed in the top navigation bar. */
 export interface TopBarInfo {
@@ -48,7 +48,7 @@ export interface TopBarInfo {
   relatedRuns: Link[]
 }
 
-interface Link {
+export interface Link {
   targetRun: LeiningRun
   /** Will omit context if the same as the current run. */
   label: string
@@ -98,7 +98,7 @@ export class TopBarTracker {
     const lastAliyah = lines.last?.aliyot[0] ?? lines.center?.aliyot[0]
 
     const run = lines.center?.run ?? lines.last?.run ?? lines.first?.run
-    if (!run) return
+    if (!run) return this.currentInfo
     newInfo.currentRun = run
 
     if (
@@ -108,7 +108,7 @@ export class TopBarTracker {
       newInfo.relatedRuns = newInfo.currentRun.leining.runs.map((run) => ({
         // Use aliyahName() to turn שביעי into חתן בראשית.
         // Use `run.type` to label הפטרות.
-        label: aliyahName(run.aliyot[0].index, run) ?? run.type,
+        label: aliyahName(run.aliyot[0].index, run) || run.type,
         targetRun: run,
       }))
 
@@ -157,6 +157,7 @@ export class TopBarTracker {
     }
 
     this.currentInfo = newInfo
+    return this.currentInfo
   }
 
   private generateAliyahRange(currentRun: LeiningRun): string[] {
@@ -165,7 +166,7 @@ export class TopBarTracker {
         ? [this.firstAliyah]
         : [this.firstAliyah, this.lastAliyah]
     )
-      .filter((a) => a != null)
+      .filter((a): a is NonNullable<typeof a> => a != null)
       .map((a) => {
         // Pass isEnd to label ראשון instead of repeating the leining name.
         const label = aliyahName(a.aliyah.index, a.run, { isEnd: true })

src/view-model/scroll-view-model.test.ts

@@ -7,7 +7,7 @@ import {
   ScrollViewModel,
 } from './scroll-view-model.ts'
 import { last } from '../calendar-model/utils.ts'
-import { renderLine } from './test-utils.ts'
+import { fetchPages, renderLine } from './test-utils.ts'
 import { containsRef } from '../calendar-model/ref-utils.ts'
 
 const testSettings: UserSettings = {
@@ -307,23 +307,6 @@ function lineContains(line: RenderedLineInfo, range: number[] | undefined) {
   return line.verses.some(({ c, v }) => c === range[0] && v === range[1])
 }
 
-async function fetchPages(
-  model: ScrollViewModel | null,
-  { count, fetchPreviousPages }: { count: number; fetchPreviousPages: boolean }
-): Promise<RenderedEntry[]> {
-  if (!model) throw new Error('No model')
-  const pages: RenderedEntry[] = [(await model.startingLocation).page]
-
-  if (fetchPreviousPages) count /= 2
-  for (let i = 0; i < count; i++) {
-    const previousPage = await model.fetchPreviousPage()
-    if (previousPage) pages.unshift(previousPage)
-    const nextPage = await model.fetchNextPage()
-    if (nextPage) pages.push(nextPage)
-  }
-  return pages
-}
-
 /** Renders enough properties of a scroll to make `deepEqual()` work with useful failures. */
 async function renderScroll(model: ScrollViewModel | null) {
   return (