Refactor complex number tests: Categorised the test and added other interesting test cases (#253)

* Clarified the category and the name of the message, that it computes the argument
of a pure imaginary number.

* Added a missing test for positive real numbers.

* Clarified the test name.

* Added a missing test that feels interesting.

* Clarified the name of the message and made it more consistent.

* Added a missing test that checks the argument of a complex number with a real and imaginary part.

* Simplified the complex number for which the argument is computed.

Author: hemalvarambhia

src/Math-Tests-Complex/PMComplexTest.class.st

@@ -162,8 +162,13 @@ PMComplexTest >> testArcTanDenominator [
 	self assert: (c2 arcTan: c1 * c1) equals: Float pi
 ]
 
-{ #category : #tests }
-PMComplexTest >> testArg [
+{ #category : #'testing - polar coordinates' }
+PMComplexTest >> testArgumentOfAComplexNumber [
+	self assert: (1 + 1 i) arg equals: Float pi / 4
+]
+
+{ #category : #'testing - polar coordinates' }
+PMComplexTest >> testArgumentOfAPositivePureImaginaryNumber [
 	"self run: #testArg"
 
 	"self debug: #testArg"
@@ -173,6 +178,16 @@ PMComplexTest >> testArg [
 	self assert: c arg equals: Float pi / 2
 ]
 
+{ #category : #'testing - polar coordinates' }
+PMComplexTest >> testArgumentOfAPositiveRealNumber [
+	self assert: (5 + 0 i) arg equals: 0.
+]
+
+{ #category : #'testing - polar coordinates' }
+PMComplexTest >> testArgumentOfPureNegativeImaginaryNumber [
+	self assert: -1 i arg equals: (Float pi / 2) negated
+]
+
 { #category : #'testing - bugs' }
 PMComplexTest >> testBug1 [
 	self assert: (0.5 * (2 + 0 i) ln) exp equals: (0.5 * 2 ln) exp