Add [defaults] placeholder support to collectors.enabled

exporter_test.go

@@ -0,0 +1,49 @@
+package main
+
+import (
+	"sort"
+	"strings"
+	"testing"
+)
+
+type expansionTestCase struct {
+	input          string
+	expectedOutput []string
+}
+
+func TestExpandEnabled(t *testing.T) {
+	expansionTests := []expansionTestCase{
+		{"", []string{}},
+		// Default case
+		{"cs,os", []string{"cs", "os"}},
+		// Placeholder expansion
+		{defaultCollectorsPlaceholder, strings.Split(defaultCollectors, ",")},
+		// De-duplication
+		{"cs,cs", []string{"cs"}},
+		// De-duplicate placeholder
+		{defaultCollectorsPlaceholder + "," + defaultCollectorsPlaceholder, strings.Split(defaultCollectors, ",")},
+		// Composite case
+		{"foo," + defaultCollectorsPlaceholder + ",bar", append(strings.Split(defaultCollectors, ","), "foo", "bar")},
+	}
+
+	for _, testCase := range expansionTests {
+		output := expandEnabledCollectors(testCase.input)
+		sort.Strings(output)
+
+		success := true
+		if len(output) != len(testCase.expectedOutput) {
+			success = false
+		} else {
+			sort.Strings(testCase.expectedOutput)
+			for idx := range output {
+				if output[idx] != testCase.expectedOutput[idx] {
+					success = false
+					break
+				}
+			}
+		}
+		if !success {
+			t.Error("For", testCase.input, "expected", testCase.expectedOutput, "got", output)
+		}
+	}
+}