test: removal of stopwords from TextRank sentences

Author: jhrcook

Sources/TextRank/TextRank.swift

@@ -18,7 +18,11 @@ public class TextRank {
     public var sentences = [Sentence]()
     public var summarizationFraction: Float = 0.2
     public var graphDamping: Float = 0.85
-    public var stopwords = [String]()
+    public var stopwords = [String]() {
+        didSet {
+            textToSentences()
+        }
+    }
 
     public init() {
         text = ""

Tests/TextRankTests/TextRankTests.swift

@@ -87,4 +87,40 @@ class TextRankTests: XCTestCase {
         XCTAssertTrue(filteredResults.count < results.results.count)
         XCTAssertTrue(filteredResults.count == 2)
     }
+
+    func testStopwordsAreRemoved() {
+        // Given
+        let text = "Here are some sentences dog cat. With intentional stopwords gator. And some words that are not."
+
+        // When
+        let textRank = TextRank(text: text)
+
+        // Then
+        XCTAssertEqual(textRank.sentences.count, 2)
+        XCTAssertEqual(textRank.sentences[0].length, 3)
+        XCTAssertEqual(textRank.sentences.filter { $0.originalTextIndex == 0 }[0].words,
+                       Set(["sentences", "dog", "cat"]))
+        XCTAssertEqual(textRank.sentences.filter { $0.originalTextIndex == 1 }[0].words,
+                       Set(["intentional", "stopwords", "gator"]))
+        XCTAssertEqual(textRank.sentences[1].length, 3)
+    }
+
+    func testAdditionalStopwords() {
+        // Given
+        let text = "Here are some sentences dog cat. With intentional stopwords gator. And some words that are not."
+        let additionalStopwords = ["dog", "gator"]
+
+        // When
+        let textRank = TextRank(text: text)
+        textRank.stopwords = additionalStopwords
+
+        // Then
+        XCTAssertEqual(textRank.sentences.count, 2)
+        XCTAssertEqual(textRank.sentences[0].length, 2)
+        XCTAssertEqual(textRank.sentences.filter { $0.originalTextIndex == 0 }[0].words,
+                       Set(["sentences", "cat"]))
+        XCTAssertEqual(textRank.sentences.filter { $0.originalTextIndex == 1 }[0].words,
+                       Set(["intentional", "stopwords"]))
+        XCTAssertEqual(textRank.sentences[1].length, 2)
+    }
 }