refactor: replaced equating coefficients with equating the polynomial.

Author: hemalvarambhia

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

@@ -239,11 +239,11 @@ PMPolynomialTest >> testPolynomialNumberSubtraction [
 
 { #category : #'testing - subtraction' }
 PMPolynomialTest >> testPolynomialNumberSubtractionInverse [
-	| polynomial |
-	polynomial := (PMPolynomial coefficients: #(2 -3 1)) - 2.
-	self assert: (polynomial at: 0) equals: 0.
-	self assert: (polynomial at: 1) equals: -3.
-	self assert: (polynomial at: 2) equals: 1.
+
+	| polynomial expected |
+	polynomial := (PMPolynomial coefficients: #( 2 -3 1 )) - 2.
+	expected := PMPolynomial coefficients: #( 0 -3 1 ).
+	self assert: polynomial equals: expected.
 	self assert: (polynomial at: 3) equals: 0
 ]