Match confidence calculation for audible results

server/finders/BookFinder.js

@@ -7,7 +7,7 @@ const FantLab = require('../providers/FantLab')
 const AudiobookCovers = require('../providers/AudiobookCovers')
 const CustomProviderAdapter = require('../providers/CustomProviderAdapter')
 const Logger = require('../Logger')
-const { levenshteinDistance, escapeRegExp } = require('../utils/index')
+const { levenshteinDistance, levenshteinSimilarity, escapeRegExp, isValidASIN } = require('../utils/index')
 const htmlSanitizer = require('../utils/htmlSanitizer')
 
 class BookFinder {
@@ -385,7 +385,11 @@ class BookFinder {
 
     if (!title) return books
 
-    books = await this.runSearch(title, author, provider, asin, maxTitleDistance, maxAuthorDistance)
+    const isTitleAsin = isValidASIN(title.toUpperCase())
+
+    let actualTitleQuery = title
+    let actualAuthorQuery = author
+    books = await this.runSearch(actualTitleQuery, actualAuthorQuery, provider, asin, maxTitleDistance, maxAuthorDistance)
 
     if (!books.length && maxFuzzySearches > 0) {
       // Normalize title and author
@@ -408,19 +412,26 @@ class BookFinder {
         for (const titlePart of titleParts) titleCandidates.add(titlePart)
         titleCandidates = titleCandidates.getCandidates()
         for (const titleCandidate of titleCandidates) {
-          if (titleCandidate == title && authorCandidate == author) continue // We already tried this
+          if (titleCandidate == actualTitleQuery && authorCandidate == actualAuthorQuery) continue // We already tried this
           if (++numFuzzySearches > maxFuzzySearches) break loop_author
-          books = await this.runSearch(titleCandidate, authorCandidate, provider, asin, maxTitleDistance, maxAuthorDistance)
+          actualTitleQuery = titleCandidate
+          actualAuthorQuery = authorCandidate
+          books = await this.runSearch(actualTitleQuery, actualAuthorQuery, provider, asin, maxTitleDistance, maxAuthorDistance)
           if (books.length) break loop_author
         }
       }
     }
 
     if (books.length) {
-      const resultsHaveDuration = provider.startsWith('audible')
+      const isAudibleProvider = provider.startsWith('audible')
-      if (resultsHaveDuration && libraryItem?.media?.duration) {
+      const libraryItemDurationMinutes = libraryItem?.media?.duration ? libraryItem.media.duration / 60 : null
-        const libraryItemDurationMinutes = libraryItem.media.duration / 60
+
-        // If provider results have duration, sort by ascendinge duration difference from libraryItem
+      books.forEach((book) => {
+        if (typeof book !== 'object' || !isAudibleProvider) return
+        book.matchConfidence = this.calculateMatchConfidence(book, libraryItemDurationMinutes, actualTitleQuery, actualAuthorQuery, isTitleAsin)
+      })
+
+      if (isAudibleProvider && libraryItemDurationMinutes) {
         books.sort((a, b) => {
           const aDuration = a.duration || Number.POSITIVE_INFINITY
           const bDuration = b.duration || Number.POSITIVE_INFINITY
@@ -433,6 +444,120 @@ class BookFinder {
     return books
   }
 
+  /**
+   * Calculate match confidence score for a book
+   * @param {Object} book - The book object to calculate confidence for
+   * @param {number|null} libraryItemDurationMinutes - Duration of library item in minutes
+   * @param {string} actualTitleQuery - Actual title query
+   * @param {string} actualAuthorQuery - Actual author query
+   * @param {boolean} isTitleAsin - Whether the title is an ASIN
+   * @returns {number|null} - Match confidence score or null if not applicable
+   */
+  calculateMatchConfidence(book, libraryItemDurationMinutes, actualTitleQuery, actualAuthorQuery, isTitleAsin) {
+    // ASIN results are always a match
+    if (isTitleAsin) return 1.0
+
+    let durationScore
+    if (libraryItemDurationMinutes && typeof book.duration === 'number') {
+      const durationDiff = Math.abs(book.duration - libraryItemDurationMinutes)
+      // Duration scores:
+      // diff | score
+      // 0    | 1.0
+      // 1    | 1.0
+      // 2    | 0.9
+      // 3    | 0.8
+      // 4    | 0.7
+      // 5    | 0.6
+      // 6    | 0.48
+      // 7    | 0.36
+      // 8    | 0.24
+      // 9    | 0.12
+      // 10   | 0.0
+      if (durationDiff <= 1) {
+        // Covers durationDiff = 0 for score 1.0
+        durationScore = 1.0
+      } else if (durationDiff <= 5) {
+        // (1, 5] - Score from 1.0 down to 0.6
+        // Linearly interpolates between (1, 1.0) and (5, 0.6)
+        // Equation: y = 1.0 - 0.08 * x
+        durationScore = 1.1 - 0.1 * durationDiff
+      } else if (durationDiff <= 10) {
+        // (5, 10] - Score from 0.6 down to 0.0
+        // Linearly interpolates between (5, 0.6) and (10, 0.0)
+        // Equation: y = 1.2 - 0.12 * x
+        durationScore = 1.2 - 0.12 * durationDiff
+      } else {
+        // durationDiff > 10 - Score is 0.0
+        durationScore = 0.0
+      }
+      Logger.debug(`[BookFinder] Duration diff: ${durationDiff}, durationScore: ${durationScore}`)
+    } else {
+      // Default score if library item duration or book duration is not available
+      durationScore = 0.1
+    }
+
+    const calculateTitleScore = (titleQuery, book, keepSubtitle = false) => {
+      const cleanTitle = cleanTitleForCompares(book.title || '', keepSubtitle)
+      const cleanSubtitle = keepSubtitle && book.subtitle ? `: ${book.subtitle}` : ''
+      const normBookTitle = `${cleanTitle}${cleanSubtitle}`
+      const normTitleQuery = cleanTitleForCompares(titleQuery, keepSubtitle)
+      const titleSimilarity = levenshteinSimilarity(normTitleQuery, normBookTitle)
+      Logger.debug(`[BookFinder] keepSubtitle: ${keepSubtitle}, normBookTitle: ${normBookTitle}, normTitleQuery: ${normTitleQuery}, titleSimilarity: ${titleSimilarity}`)
+      return titleSimilarity
+    }
+    const titleQueryHasSubtitle = hasSubtitle(actualTitleQuery)
+    const titleScore = calculateTitleScore(actualTitleQuery, book, titleQueryHasSubtitle)
+
+    let authorScore
+    const normAuthorQuery = cleanAuthorForCompares(actualAuthorQuery)
+    const normBookAuthor = cleanAuthorForCompares(book.author || '')
+    if (!normAuthorQuery) {
+      // Original query had no author
+      authorScore = 1.0 // Neutral score
+    } else {
+      // Original query HAS an author (cleanedQueryAuthorForScore is not empty)
+      if (normBookAuthor) {
+        const bookAuthorParts = normBookAuthor.split(',').map((name) => name.trim().toLowerCase())
+        // Filter out empty parts that might result from ", ," or trailing/leading commas
+        const validBookAuthorParts = bookAuthorParts.filter((p) => p.length > 0)
+
+        if (validBookAuthorParts.length === 0) {
+          // Book author string was present but effectively empty (e.g. ",,")
+          // Since cleanedQueryAuthorForScore is non-empty here, this is a mismatch.
+          authorScore = 0.0
+        } else {
+          let maxPartScore = levenshteinSimilarity(normAuthorQuery, normBookAuthor)
+          Logger.debug(`[BookFinder] normAuthorQuery: ${normAuthorQuery}, normBookAuthor: ${normBookAuthor}, similarity: ${maxPartScore}`)
+          if (validBookAuthorParts.length > 1 || normBookAuthor.includes(',')) {
+            validBookAuthorParts.forEach((part) => {
+              // part is guaranteed to be non-empty here
+              // cleanedQueryAuthorForScore is also guaranteed non-empty here.
+              // levenshteinDistance lowercases by default, but part is already lowercased.
+              const similarity = levenshteinSimilarity(normAuthorQuery, part)
+              Logger.debug(`[BookFinder] normAuthorQuery: ${normAuthorQuery}, bookAuthorPart: ${part}, similarity: ${similarity}`)
+              const currentPartScore = similarity
+              maxPartScore = Math.max(maxPartScore, currentPartScore)
+            })
+          }
+          authorScore = maxPartScore
+        }
+      } else {
+        // Book has NO author (or not a string, or empty string)
+        // Query has an author (cleanedQueryAuthorForScore is non-empty), book does not.
+        authorScore = 0.0
+      }
+    }
+
+    const W_DURATION = 0.7
+    const W_TITLE = 0.2
+    const W_AUTHOR = 0.1
+
+    Logger.debug(`[BookFinder] Duration score: ${durationScore}, Title score: ${titleScore}, Author score: ${authorScore}`)
+    const confidence = W_DURATION * durationScore + W_TITLE * titleScore + W_AUTHOR * authorScore
+    Logger.debug(`[BookFinder] Confidence: ${confidence}`)
+    return Math.max(0, Math.min(1, confidence))
+  }
+
   /**
    * Search for books
    *
@@ -464,6 +589,7 @@ class BookFinder {
     } else {
       books = await this.getGoogleBooksResults(title, author)
     }
+
     books.forEach((book) => {
       if (book.description) {
         book.description = htmlSanitizer.sanitize(book.description)
@@ -505,6 +631,9 @@ class BookFinder {
 }
 module.exports = new BookFinder()
 
+function hasSubtitle(title) {
+  return title.includes(':') || title.includes(' - ')
+}
 function stripSubtitle(title) {
   if (title.includes(':')) {
     return title.split(':')[0].trim()
@@ -523,12 +652,12 @@ function replaceAccentedChars(str) {
   }
 }
 
-function cleanTitleForCompares(title) {
+function cleanTitleForCompares(title, keepSubtitle = false) {
   if (!title) return ''
   title = stripRedundantSpaces(title)
 
   // Remove subtitle if there (i.e. "Cool Book: Coolest Ever" becomes "Cool Book")
-  let stripped = stripSubtitle(title)
+  let stripped = keepSubtitle ? title : stripSubtitle(title)
 
   // Remove text in paranthesis (i.e. "Ender's Game (Ender's Saga)" becomes "Ender's Game")
   let cleaned = stripped.replace(/ *\([^)]*\) */g, '')

test/server/finders/BookFinder.test.js

@@ -5,6 +5,12 @@ const bookFinder = require('../../../server/finders/BookFinder')
 const { LogLevel } = require('../../../server/utils/constants')
 const Logger = require('../../../server/Logger')
 Logger.setLogLevel(LogLevel.INFO)
+const { levenshteinDistance } = require('../../../server/utils/index')
+
+// levenshteinDistance is needed for manual calculation of expected scores in tests.
+// Assuming it's accessible for testing purposes or we mock/replicate its basic behavior if needed.
+// For now, we'll assume bookFinder.search uses it internally correctly.
+// const { levenshteinDistance } = require('../../../server/utils/index') // Not used directly in test logic, but for reasoning.
 
 describe('TitleCandidates', () => {
   describe('cleanAuthor non-empty', () => {
@@ -326,31 +332,262 @@ describe('search', () => {
     const sorted = [{ duration: 1000 }, { duration: 500 }, { duration: 2000 }, { duration: 3000 }]
 
     beforeEach(() => {
-      runSearchStub.withArgs(t, a, provider).resolves(unsorted)
+      runSearchStub.withArgs(t, a, provider).resolves(structuredClone(unsorted))
+    })
+
+    afterEach(() => {
+      sinon.restore()
     })
 
     it('returns results sorted by library item duration diff', async () => {
-      expect(await bookFinder.search(libraryItem, provider, t, a)).to.deep.equal(sorted)
+      const result = (await bookFinder.search(libraryItem, provider, t, a)).map((r) => (r.duration ? { duration: r.duration } : {}))
+      expect(result).to.deep.equal(sorted)
     })
 
     it('returns unsorted results if library item is null', async () => {
-      expect(await bookFinder.search(null, provider, t, a)).to.deep.equal(unsorted)
+      const result = (await bookFinder.search(null, provider, t, a)).map((r) => (r.duration ? { duration: r.duration } : {}))
+      expect(result).to.deep.equal(unsorted)
     })
 
     it('returns unsorted results if library item duration is undefined', async () => {
-      expect(await bookFinder.search({ media: {} }, provider, t, a)).to.deep.equal(unsorted)
+      const result = (await bookFinder.search({ media: {} }, provider, t, a)).map((r) => (r.duration ? { duration: r.duration } : {}))
+      expect(result).to.deep.equal(unsorted)
     })
 
     it('returns unsorted results if library item media is undefined', async () => {
-      expect(await bookFinder.search({}, provider, t, a)).to.deep.equal(unsorted)
+      const result = (await bookFinder.search({}, provider, t, a)).map((r) => (r.duration ? { duration: r.duration } : {}))
+      expect(result).to.deep.equal(unsorted)
     })
 
     it('should return a result last if it has no duration', async () => {
       const unsorted = [{}, { duration: 3000 }, { duration: 2000 }, { duration: 1000 }, { duration: 500 }]
       const sorted = [{ duration: 1000 }, { duration: 500 }, { duration: 2000 }, { duration: 3000 }, {}]
-      runSearchStub.withArgs(t, a, provider).resolves(unsorted)
+      runSearchStub.withArgs(t, a, provider).resolves(structuredClone(unsorted))
+      const result = (await bookFinder.search(libraryItem, provider, t, a)).map((r) => (r.duration ? { duration: r.duration } : {}))
+      expect(result).to.deep.equal(sorted)
+    })
+  })
 
-      expect(await bookFinder.search(libraryItem, provider, t, a)).to.deep.equal(sorted)
+  describe('matchConfidence score', () => {
+    const W_DURATION = 0.7
+    const W_TITLE = 0.2
+    const W_AUTHOR = 0.1
+    const DEFAULT_DURATION_SCORE_MISSING_INFO = 0.1
+
+    const libraryItemPerfectDuration = { media: { duration: 600 } } // 10 minutes
+
+    // Helper to calculate expected title/author score based on Levenshtein
+    // Assumes queryPart and bookPart are already "cleaned" for length calculation consistency with BookFinder.js
+    const calculateStringMatchScore = (cleanedQueryPart, cleanedBookPart) => {
+      if (!cleanedQueryPart) return cleanedBookPart ? 0 : 1 // query empty: 1 if book empty, else 0
+      if (!cleanedBookPart) return 0 // query non-empty, book empty: 0
+
+      // Use the imported levenshteinDistance. It defaults to case-insensitive, which is what we want.
+      const distance = levenshteinDistance(cleanedQueryPart, cleanedBookPart)
+      return Math.max(0, 1 - distance / Math.max(cleanedQueryPart.length, cleanedBookPart.length))
+    }
+
+    beforeEach(() => {
+      runSearchStub.resolves([])
+    })
+
+    afterEach(() => {
+      sinon.restore()
+    })
+
+    describe('for audible provider', () => {
+      const provider = 'audible'
+
+      it('should be 1.0 for perfect duration, title, and author match', async () => {
+        const bookResults = [{ duration: 10, title: 'The Great Novel', author: 'John Doe' }]
+        runSearchStub.resolves(bookResults)
+        const results = await bookFinder.search(libraryItemPerfectDuration, provider, 'The Great Novel', 'John Doe')
+        // durationScore = 1.0 (diff 0 <= 1 min)
+        // titleScore = 1.0 (exact match)
+        // authorScore = 1.0 (exact match)
+        const expectedConfidence = W_DURATION * 1.0 + W_TITLE * 1.0 + W_AUTHOR * 1.0
+        expect(results[0].matchConfidence).to.be.closeTo(expectedConfidence, 0.001)
+      })
+
+      it('should correctly score a large duration mismatch', async () => {
+        const bookResults = [{ duration: 21, title: 'The Great Novel', author: 'John Doe' }] // 21 min, diff = 11 min
+        runSearchStub.resolves(bookResults)
+        const results = await bookFinder.search(libraryItemPerfectDuration, provider, 'The Great Novel', 'John Doe')
+        // durationScore = 0.0
+        // titleScore = 1.0
+        // authorScore = 1.0
+        const expectedConfidence = W_DURATION * 0.0 + W_TITLE * 1.0 + W_AUTHOR * 1.0
+        expect(results[0].matchConfidence).to.be.closeTo(expectedConfidence, 0.001)
+      })
+
+      it('should correctly score a medium duration mismatch', async () => {
+        const bookResults = [{ duration: 16, title: 'The Great Novel', author: 'John Doe' }] // 16 min, diff = 6 min
+        runSearchStub.resolves(bookResults)
+        const results = await bookFinder.search(libraryItemPerfectDuration, provider, 'The Great Novel', 'John Doe')
+        // durationScore = 1.2 - 6 * 0.12 = 0.48
+        // titleScore = 1.0
+        // authorScore = 1.0
+        const expectedConfidence = W_DURATION * 0.48 + W_TITLE * 1.0 + W_AUTHOR * 1.0
+        expect(results[0].matchConfidence).to.be.closeTo(expectedConfidence, 0.001)
+      })
+
+      it('should correctly score a minor duration mismatch', async () => {
+        const bookResults = [{ duration: 14, title: 'The Great Novel', author: 'John Doe' }] // 14 min, diff = 4 min
+        runSearchStub.resolves(bookResults)
+        const results = await bookFinder.search(libraryItemPerfectDuration, provider, 'The Great Novel', 'John Doe')
+        // durationScore = 1.1 - 4 * 0.1 = 0.7
+        // titleScore = 1.0
+        // authorScore = 1.0
+        const expectedConfidence = W_DURATION * 0.7 + W_TITLE * 1.0 + W_AUTHOR * 1.0
+        expect(results[0].matchConfidence).to.be.closeTo(expectedConfidence, 0.001)
+      })
+
+      it('should correctly score a tiny duration mismatch', async () => {
+        const bookResults = [{ duration: 11, title: 'The Great Novel', author: 'John Doe' }] // 11 min, diff = 1 min
+        runSearchStub.resolves(bookResults)
+        const results = await bookFinder.search(libraryItemPerfectDuration, provider, 'The Great Novel', 'John Doe')
+        // durationScore = 1.0
+        // titleScore = 1.0
+        // authorScore = 1.0
+        const expectedConfidence = W_DURATION * 1.0 + W_TITLE * 1.0 + W_AUTHOR * 1.0
+        expect(results[0].matchConfidence).to.be.closeTo(expectedConfidence, 0.001)
+      })
+
+      it('should use default duration score if libraryItem duration is missing', async () => {
+        const bookResults = [{ duration: 10, title: 'The Great Novel', author: 'John Doe' }]
+        runSearchStub.resolves(bookResults)
+        const results = await bookFinder.search({ media: {} }, provider, 'The Great Novel', 'John Doe')
+        // durationScore = DEFAULT_DURATION_SCORE_MISSING_INFO (0.2)
+        const expectedConfidence = W_DURATION * DEFAULT_DURATION_SCORE_MISSING_INFO + W_TITLE * 1.0 + W_AUTHOR * 1.0
+        expect(results[0].matchConfidence).to.be.closeTo(expectedConfidence, 0.001)
+      })
+
+      it('should use default duration score if book duration is missing', async () => {
+        const bookResults = [{ title: 'The Great Novel', author: 'John Doe' }] // No duration in book
+        runSearchStub.resolves(bookResults)
+        const results = await bookFinder.search(libraryItemPerfectDuration, provider, 'The Great Novel', 'John Doe')
+        // durationScore = DEFAULT_DURATION_SCORE_MISSING_INFO (0.2)
+        const expectedConfidence = W_DURATION * DEFAULT_DURATION_SCORE_MISSING_INFO + W_TITLE * 1.0 + W_AUTHOR * 1.0
+        expect(results[0].matchConfidence).to.be.closeTo(expectedConfidence, 0.001)
+      })
+
+      it('should correctly score a partial title match', async () => {
+        const bookResults = [{ duration: 10, title: 'Novel', author: 'John Doe' }]
+        runSearchStub.resolves(bookResults)
+        // Query: 'Novel Ex', Book: 'Novel'
+        // cleanTitleForCompares('Novel Ex') -> 'novel ex' (length 8)
+        // cleanTitleForCompares('Novel')    -> 'novel' (length 5)
+        // levenshteinDistance('novel ex', 'novel') = 3
+        const results = await bookFinder.search(libraryItemPerfectDuration, provider, 'Novel Ex', 'John Doe')
+        const expectedTitleScore = calculateStringMatchScore('novel ex', 'novel') // 1 - (3/8) = 0.625
+        const expectedConfidence = W_DURATION * 1.0 + W_TITLE * expectedTitleScore + W_AUTHOR * 1.0
+        expect(results[0].matchConfidence).to.be.closeTo(expectedConfidence, 0.001)
+      })
+
+      it('should correctly score a partial author match (comma-separated)', async () => {
+        const bookResults = [{ duration: 10, title: 'The Great Novel', author: 'Jane Smith, Jon Doee' }]
+        runSearchStub.resolves(bookResults)
+        // Query: 'Jon Doe', Book part: 'Jon Doee'
+        // cleanAuthorForCompares('Jon Doe') -> 'jon doe' (length 7)
+        // book author part (already lowercased) -> 'jon doee' (length 8)
+        // levenshteinDistance('jon doe', 'jon doee') = 1
+        const results = await bookFinder.search(libraryItemPerfectDuration, provider, 'The Great Novel', 'Jon Doe')
+        // For the author part 'jon doee':
+        const expectedAuthorPartScore = calculateStringMatchScore('jon doe', 'jon doee') // 1 - (1/7)
+        // Assuming 'jane smith' gives a lower or 0 score, max score will be from 'jon doee'
+        const expectedConfidence = W_DURATION * 1.0 + W_TITLE * 1.0 + W_AUTHOR * expectedAuthorPartScore
+        expect(results[0].matchConfidence).to.be.closeTo(expectedConfidence, 0.001)
+      })
+
+      it('should give authorScore 0 if query has author but book does not', async () => {
+        const bookResults = [{ duration: 10, title: 'The Great Novel', author: null }]
+        runSearchStub.resolves(bookResults)
+        const results = await bookFinder.search(libraryItemPerfectDuration, provider, 'The Great Novel', 'John Doe')
+        // authorScore = 0.0
+        const expectedConfidence = W_DURATION * 1.0 + W_TITLE * 1.0 + W_AUTHOR * 0.0
+        expect(results[0].matchConfidence).to.be.closeTo(expectedConfidence, 0.001)
+      })
+
+      it('should give authorScore 1.0 if query has no author', async () => {
+        const bookResults = [{ duration: 10, title: 'The Great Novel', author: 'John Doe' }]
+        runSearchStub.resolves(bookResults)
+        const results = await bookFinder.search(libraryItemPerfectDuration, provider, 'The Great Novel', '') // Empty author
+        expect(results[0].matchConfidence).to.be.closeTo(1.0, 0.001)
+      })
+
+      it('handles book author string that is only commas correctly (score 0)', async () => {
+        const bookResults = [{ duration: 10, title: 'The Great Novel', author: ',, ,, ,' }]
+        runSearchStub.resolves(bookResults)
+        const results = await bookFinder.search(libraryItemPerfectDuration, provider, 'The Great Novel', 'John Doe')
+        // cleanedQueryAuthorForScore = "john doe"
+        // book.author leads to validBookAuthorParts being empty.
+        // authorScore = 0.0
+        const expectedConfidence = W_DURATION * 1.0 + W_TITLE * 1.0 + W_AUTHOR * 0.0
+        expect(results[0].matchConfidence).to.be.closeTo(expectedConfidence, 0.001)
+      })
+
+      it('should return 1.0 for ASIN results', async () => {
+        const bookResults = [{ duration: 10, title: 'The Great Novel', author: 'John Doe' }]
+        runSearchStub.resolves(bookResults)
+        const results = await bookFinder.search(libraryItemPerfectDuration, provider, 'B000F28ZJ4', null)
+        expect(results[0].matchConfidence).to.be.closeTo(1.0, 0.001)
+      })
+
+      it('should return 1.0 when author matches one of the book authors', async () => {
+        const bookResults = [{ duration: 10, title: 'The Great Novel', author: 'John Doe, Jane Smith' }]
+        runSearchStub.resolves(bookResults)
+        const results = await bookFinder.search(libraryItemPerfectDuration, provider, 'The Great Novel', 'John Doe')
+        expect(results[0].matchConfidence).to.be.closeTo(1.0, 0.001)
+      })
+
+      it('should return 1.0 when author query and multiple book authors are the same', async () => {
+        const bookResults = [{ duration: 10, title: 'The Great Novel', author: 'John Doe, Jane Smith' }]
+        runSearchStub.resolves(bookResults)
+        const results = await bookFinder.search(libraryItemPerfectDuration, provider, 'The Great Novel', 'John Doe, Jane Smith')
+        expect(results[0].matchConfidence).to.be.closeTo(1.0, 0.001)
+      })
+
+      it('should correctly score against a book with a subtitle when the query has a subtitle', async () => {
+        const bookResults = [{ duration: 10, title: 'The Great Novel', subtitle: 'A Novel', author: 'John Doe' }]
+        runSearchStub.resolves(bookResults)
+        const results = await bookFinder.search(libraryItemPerfectDuration, provider, 'The Great Novel: A Novel', 'John Doe')
+        expect(results[0].matchConfidence).to.be.closeTo(1.0, 0.001)
+      })
+
+      it('should correctly score against a book with a subtitle when the query does not have a subtitle', async () => {
+        const bookResults = [{ duration: 10, title: 'The Great Novel', subtitle: 'A Novel', author: 'John Doe' }]
+        runSearchStub.resolves(bookResults)
+        const results = await bookFinder.search(libraryItemPerfectDuration, provider, 'The Great Novel', 'John Doe')
+        expect(results[0].matchConfidence).to.be.closeTo(1.0, 0.001)
+      })
+
+      describe('after fuzzy searches', () => {
+        it('should return 1.0 for a title candidate match', async () => {
+          const bookResults = [{ duration: 10, title: 'The Great Novel', author: 'John Doe' }]
+          runSearchStub.resolves([])
+          runSearchStub.withArgs('the great novel', 'john doe').resolves(bookResults)
+          const results = await bookFinder.search(libraryItemPerfectDuration, provider, 'The Great Novel - A Novel', 'John Doe')
+          expect(results[0].matchConfidence).to.be.closeTo(1.0, 0.001)
+        })
+
+        it('should return 1.0 for an author candidate match', async () => {
+          const bookResults = [{ duration: 10, title: 'The Great Novel', author: 'John Doe' }]
+          runSearchStub.resolves([])
+          runSearchStub.withArgs('the great novel', 'john doe').resolves(bookResults)
+          const results = await bookFinder.search(libraryItemPerfectDuration, provider, 'The Great Novel', 'John Doe, Jane Smith')
+          expect(results[0].matchConfidence).to.be.closeTo(1.0, 0.001)
+        })
+      })
+    })
+
+    describe('for non-audible provider (e.g., google)', () => {
+      const provider = 'google'
+      it('should have not have matchConfidence', async () => {
+        const bookResults = [{ title: 'The Great Novel', author: 'John Doe' }]
+        runSearchStub.resolves(bookResults)
+        const results = await bookFinder.search(libraryItemPerfectDuration, provider, 'The Great Novel', 'John Doe')
+        expect(results[0]).to.not.have.property('matchConfidence')
+      })
     })
   })
 })