Merge pull request #20687 from Yoast/218-improve-plural-form-for-fren…

…ch-word-complexity

Improve plural form recognition for French word complexity

packages/yoastseo/spec/languageProcessing/languages/fr/helpers/checkIfWordIsComplexSpec.js

@@ -32,6 +32,20 @@ describe( "a test checking if the word is complex in French",  function() {
 		expect( checkIfWordIsComplex( wordComplexityConfig, "ouvrir", premiumData ) ).toEqual( false );
 	} );
 
+	it( "returns irregular plural as non-complex if its singular version is found in the list", function() {
+		expect( checkIfWordIsComplex( wordComplexityConfig,  "principaux", premiumData ) ).toEqual( false );
+		expect( checkIfWordIsComplex( wordComplexityConfig, "principal", premiumData ) ).toEqual( false );
+	} );
+
+	it( "returns irregular plural words longer than 9 characters as complex if it is not in the list", function() {
+		expect( checkIfWordIsComplex( wordComplexityConfig, "expérimentaux", premiumData ) ).toEqual( true );
+	} );
+
+	it( "returns an -x plural as non-complex if its singular version is found in the list", function() {
+		expect( checkIfWordIsComplex( wordComplexityConfig,  "vaisseaux", premiumData ) ).toEqual( false );
+		expect( checkIfWordIsComplex( wordComplexityConfig, "vaisseau", premiumData ) ).toEqual( false );
+	} );
+
 	it( "returns words longer than 9 characters preceded by article l' or preposition d' as non complex if the words are in the list", function() {
 		expect( checkIfWordIsComplex( wordComplexityConfig, "l'ambassadeur", premiumData ) ).toEqual( false );
 		expect( checkIfWordIsComplex( wordComplexityConfig, "d'échantillon", premiumData ) ).toEqual( false );

packages/yoastseo/src/languageProcessing/languages/fr/helpers/checkIfWordIsComplex.js

@@ -44,17 +44,24 @@ export default function checkIfWordIsComplex( config, word, premiumData ) {
 	 * word longer than 9 characters is not complex if it starts with capital letter.
 	 */
 	if ( word[ 0 ].toLowerCase() === word[ 0 ] ) {
+		const standardSPluralSuffixesRegex = new RegExp( premiumData.suffixGroupsComplexity.standardSuffixesWithSplural );
+		const standardXPluralSuffixesRegex = new RegExp( premiumData.suffixGroupsComplexity.standardSuffixesWithXplural );
+		const irregularPluralSingularSuffixes = premiumData.suffixGroupsComplexity.irregularPluralSingularSuffixes;
+		const irregularPluralSuffixRegex = new RegExp( irregularPluralSingularSuffixes[ 0 ] );
+
 		/*
 		 * If a word is longer than 9 characters and doesn't start with capital letter,
-		 * we check further whether it is a plural ending in -s. If it is, we remove the -s suffix
+		 * we check further whether it is a plural that ends on the -s or -x plural suffix. If it is, we remove the plural suffix
 		 * and check if the singular word can be found in the frequency list.
+		 * if it is a plural that does not end on -s or -x but on -aux, we replace the plural -aux suffix with the singular suffix -al.
 		 * The word is not complex if the singular form is in the list.
 		 */
-		if ( word.endsWith( "s" ) ) {
+		if ( standardSPluralSuffixesRegex.test( word ) || standardXPluralSuffixesRegex.test( word ) ) {
 			word = word.substring( 0, word.length - 1 );
-			return ! frequencyList.includes( word );
+		} else if ( irregularPluralSuffixRegex.test( word ) ) {
+			word = word.replace( irregularPluralSuffixRegex, irregularPluralSingularSuffixes[ 1 ] );
 		}
-		return true;
+		return ! frequencyList.includes( word );
 	}
 
 	return false;