fixed vcpus-to-memory ratio calc to use ceiling (#18)

* fixed vcpus-to-memory ratio calc to use ceiling

* fix ratio calc when vcpus is 0

Author: bwagner5

pkg/selector/comparators.go

@@ -141,11 +141,12 @@ func supportSyntaxToBool(instanceTypeSupport *string) *bool {
 }
 
 func calculateVCpusToMemoryRatio(vcpusVal *int64, memoryVal *int64) *float64 {
-	if vcpusVal == nil || memoryVal == nil {
+	if vcpusVal == nil || *vcpusVal == 0 || memoryVal == nil {
 		return nil
 	}
 	// normalize vcpus to a mebivcpu value
-	return aws.Float64(float64(*memoryVal) / float64(*vcpusVal*1024))
+	result := math.Ceil(float64(*memoryVal) / float64(*vcpusVal*1024))
+	return &result
 }
 
 // Slice helper function

pkg/selector/comparators_internal_test.go

@@ -217,17 +217,22 @@ func TestCalculateVCpusToMemoryRatio(t *testing.T) {
 	vcpus := aws.Int64(4)
 	memory := aws.Int64(4096)
 	ratio := calculateVCpusToMemoryRatio(vcpus, memory)
-	h.Assert(t, *ratio == 1.00, "nil should evaluate to nil")
+	h.Assert(t, *ratio == 1.00, "ratio should equal 1:1")
 
 	vcpus = aws.Int64(2)
 	memory = aws.Int64(4096)
 	ratio = calculateVCpusToMemoryRatio(vcpus, memory)
-	h.Assert(t, *ratio == 2.00, "nil should evaluate to nil")
+	h.Assert(t, *ratio == 2.00, "ratio should equal 1:2")
 
 	vcpus = aws.Int64(1)
 	memory = aws.Int64(512)
 	ratio = calculateVCpusToMemoryRatio(vcpus, memory)
-	h.Assert(t, *ratio == 0.50, "nil should evaluate to nil")
+	h.Assert(t, *ratio == 1.0, "ratio should take the ceiling which equals 1:1")
+
+	vcpus = aws.Int64(0)
+	memory = aws.Int64(512)
+	ratio = calculateVCpusToMemoryRatio(vcpus, memory)
+	h.Assert(t, ratio == nil, "ratio should be nil when vcpus is 0")
 }
 
 func TestCalculateVCpusToMemoryRatio_Nil(t *testing.T) {