Added some tests. Changed logic about testing if elements are integer…

…. We can only compute a mean on objects that can be added.

src/Collections-Sequenceable/SortedCollection.class.st

@@ -235,7 +235,12 @@ SortedCollection >> median [
 	"Return the middle element, or as close as we can get."
 	"{1 . 2 . 3 . 4 . 5} asSortedCollection  median >>> 3"
 
-	^ self at: self size + 1 // 2
+	| size middle |
+ 	size := self size.
+ 	middle := (size + 1) // 2.
+ 	^ size even
+			ifTrue: [ ((self at: middle) + (self at: middle + 1)) / 2 ]
+			ifFalse: [ self at: middle ]
 ]
 
 { #category : #private }

src/Collections-Tests/SortedCollectionTest.class.st

@@ -719,11 +719,21 @@ SortedCollectionTest >> testLastIndexOfStartingAt [
 ]
 
 { #category : #'tests - basic' }
-SortedCollectionTest >> testMedian [
+SortedCollectionTest >> testMedianForEvenSizeCollection [
 
 	|aSortedCollection|
-	aSortedCollection := (1 to: 10) asSortedCollection.
-	self assert: aSortedCollection median equals: 5.
+	aSortedCollection := {1 .2 . 3 . 4 . 5 . 6 } asSortedCollection.
+	self assert: aSortedCollection median equals: 3.5
+
+
+]
+
+{ #category : #'tests - basic' }
+SortedCollectionTest >> testMedianForOddSizeCollection [
+
+	|aSortedCollection|
+	aSortedCollection := {1 .2 . 3 . 4 . 5 . 6 .7} asSortedCollection.
+	self assert: aSortedCollection median equals: 4.
 
 	aSortedCollection := SortedCollection new.
 	aSortedCollection 
@@ -735,6 +745,14 @@ SortedCollectionTest >> testMedian [
 
 ]
 
+{ #category : #'tests - basic' }
+SortedCollectionTest >> testMedianWithNumbers [
+
+	| aSortedCollection |
+	aSortedCollection := (1 to: 10) asSortedCollection.
+ 	self assert: aSortedCollection median equals: 5.5
+]
+
 { #category : #'tests - basic' }
 SortedCollectionTest >> testRemoveAll [
 	"Allows one to remove all elements of a collection"