Add Missing Tests for AISzymkiewiczSimpsonCoefficientTest

src/AI-EditDistances-Tests/AISzymkiewiczSimpsonCoefficientTest.class.st

@@ -18,3 +18,27 @@ AISzymkiewiczSimpsonCoefficientTest >> testSzymkiewiczSimpsonDistanceTo [
 
 	self assert: (metric distanceBetween: #( 12 34 56 7 2 3 ) asSet and: #( 3 5 43 ) asSet) closeTo: 0.33333333333.
 ]
+
+{ #category : 'tests' }
+AISzymkiewiczSimpsonCoefficientTest >> testEmptySets [
+	"Checks that the Szymkiewicz-Simpson coefficient for empty sets is 1.0."
+	| metric |
+	metric := AISzymkiewiczSimpsonDistance new.
+	self assert: (metric distanceBetween: #() asSet and: #() asSet) equals: 1.0.
+]
+
+{ #category : 'tests' }
+AISzymkiewiczSimpsonCoefficientTest >> testIdenticalSets [
+	"Checks that the Szymkiewicz-Simpson coefficient for identical sets is 1.0."
+	| metric |
+	metric := AISzymkiewiczSimpsonDistance new.
+	self assert: (metric distanceBetween: #(1 2 3) asSet and: #(1 2 3) asSet) equals: 1.0.
+]
+
+{ #category : 'tests' }
+AISzymkiewiczSimpsonCoefficientTest >> testDisjointSets [
+	"Checks that the Szymkiewicz-Simpson coefficient for disjoint sets is 0.0."
+	| metric |
+	metric := AISzymkiewiczSimpsonDistance new.
+	self assert: (metric distanceBetween: #(1 2 3) asSet and: #(4 5 6) asSet) equals: 0.0.
+]

src/AI-EditDistances/AISzymkiewiczSimpsonDistance.class.st

@@ -12,10 +12,15 @@ Class {
 }
 
 { #category : 'api' }
-AISzymkiewiczSimpsonDistance >> distanceBetween: aSet and: anotherSet [
+AISzymkiewiczSimpsonDistance >> distanceBetween: firstSet and: secondSet [
 
 	| intersection minSize |
-	intersection := (aSet intersection: anotherSet ) size.
-	minSize := aSet size min: anotherSet size.
-	^ (intersection / minSize) asFloat
+
+    (firstSet isEmpty and: [ secondSet isEmpty ]) ifTrue: [ ^ 1.0 ].
+
+    intersection := firstSet intersection: secondSet.
+    minSize := (firstSet size min: secondSet size).
+    minSize = 0 ifTrue: [ ^ 0.0 ].
+
+    ^ intersection size / minSize
 ]