add output option for one-line comma separated (#66)

* add output option for one-line comma separated

* move one-line output to outputs.go

Author: bwagner5

cmd/main.go

@@ -42,6 +42,7 @@ const (
 	terraformHCL    = "terraform-hcl"
 	tableOutput     = "table"
 	tableWideOutput = "table-wide"
+	oneLine         = "one-line"
 )
 
 // Filter Flag Constants
@@ -110,6 +111,7 @@ Full docs can be found at github.com/aws/amazon-` + binName
 	cliOutputTypes := []string{
 		tableOutput,
 		tableWideOutput,
+		oneLine,
 	}
 	resultsOutputFn := outputs.SimpleInstanceTypeOutput
 
@@ -267,6 +269,8 @@ func getOutputFn(outputFlag *string, currentFn selector.InstanceTypesOutputFn) s
 			return selector.InstanceTypesOutputFn(outputs.TableOutputWide)
 		case tableOutput:
 			return selector.InstanceTypesOutputFn(outputs.TableOutputShort)
+		case oneLine:
+			return selector.InstanceTypesOutputFn(outputs.OneLineOutput)
 		}
 	}
 	return outputFn

pkg/selector/outputs/outputs.go

@@ -260,3 +260,15 @@ func TableOutputWide(instanceTypeInfoSlice []*ec2.InstanceTypeInfo) []string {
 	w.Flush()
 	return []string{buf.String()}
 }
+
+// OneLineOutput is an output function which prints the instance type names on a single line separated by commas
+func OneLineOutput(instanceTypeInfoSlice []*ec2.InstanceTypeInfo) []string {
+	instanceTypeNames := []string{}
+	for _, instanceType := range instanceTypeInfoSlice {
+		instanceTypeNames = append(instanceTypeNames, *instanceType.InstanceType)
+	}
+	if len(instanceTypeNames) == 0 {
+		return []string{}
+	}
+	return []string{strings.Join(instanceTypeNames, ",")}
+}

pkg/selector/outputs/outputs_test.go

@@ -129,3 +129,16 @@ func TestTableOutput_MBtoGB(t *testing.T) {
 	outputStr = strings.Join(instanceTypeOut, "")
 	h.Assert(t, strings.Contains(outputStr, "15.000"), "table should include 15.000 GB of memory")
 }
+
+func TestOneLineOutput(t *testing.T) {
+	instanceTypes := getInstanceTypes(t, "t3_micro_and_p3_16xl.json")
+	instanceTypeOut := outputs.OneLineOutput(instanceTypes)
+	h.Assert(t, len(instanceTypeOut) == 1, "Should always return 1 line")
+	h.Assert(t, instanceTypeOut[0] == "t3.micro,p3.16xlarge", "Should return both instance types separated by a comma")
+
+	instanceTypeOut = outputs.OneLineOutput([]*ec2.InstanceTypeInfo{})
+	h.Assert(t, len(instanceTypeOut) == 0, "Should return 0 instance types when passed empty slice")
+
+	instanceTypeOut = outputs.OneLineOutput(nil)
+	h.Assert(t, len(instanceTypeOut) == 0, "Should return 0 instance types when passed nil")
+}