refactor: used the assert: equals: message to take advantage of Polynomial's = message.

Author: hemalvarambhia

src/Math-Tests-Polynomials/PMPolynomialTest.class.st

@@ -40,11 +40,10 @@ PMPolynomialTest >> testPolynomialAdditionIsCommutative [
 PMPolynomialTest >> testPolynomialDerivative [
 	"Code example 2.3"
 
-	| polynomial |
-	polynomial := (PMPolynomial coefficients: #(-3 7 2 1)) derivative.
-	self assert: (polynomial at: 0) equals: 7.
-	self assert: (polynomial at: 1) equals: 4.
-	self assert: (polynomial at: 2) equals: 3.
+	| polynomial expectedDerivative |
+	polynomial := (PMPolynomial coefficients: #( -3 7 2 1 )) derivative.
+	expectedDerivative := PMPolynomial coefficients: #( 7 4 3 ).
+	self assert: polynomial equals: expectedDerivative.
 	self assert: (polynomial at: 3) equals: 0.
 	self assert: (polynomial at: 4) equals: 0
 ]