Making sure unknown OS returns error

Author: phayes

entropychecker.go

@@ -17,6 +17,9 @@ var MinimumEntropy = 128
 // Waiting for entropy will time out after this amount of time. Setting to zero will never time out.
 var Timeout = time.Second * 10
 
+// The only supported OS is linux at this time.
+var supportedOS = "linux"
+
 // ErrTimeout is for when the system waits too long and gives up
 var ErrTimeout = errors.New("entropychecker: Timed out waiting for sufficient entropy")
 
@@ -25,7 +28,7 @@ var ErrUnsupportedOS = errors.New("entropychecker: Unsupported OS. Only Linux is
 
 // GetEntropy gets the entropy estimate. Returns the estimated entropy in bits
 func GetEntropy() (int, error) {
-	if runtime.GOOS != "linux" {
+	if runtime.GOOS != supportedOS {
 		return 0, ErrUnsupportedOS
 	}
 
@@ -38,7 +41,7 @@ func GetEntropy() (int, error) {
 
 // WaitForEntropy blocks until sufficient entropy is available
 func WaitForEntropy() error {
-	if runtime.GOOS != "linux" {
+	if runtime.GOOS != supportedOS {
 		return ErrUnsupportedOS
 	}
 

entropychecker_test.go

@@ -32,10 +32,21 @@ func TestEntropyChecker(t *testing.T) {
 }
 
 func TestFailure(t *testing.T) {
+	// Make sure we get a an error if we time out
 	Timeout = 200 * time.Millisecond
 	MinimumEntropy = 100000
 	err := WaitForEntropy()
 	if err == nil {
 		t.Error("Should get error when timeout waited too long")
 	}
+
+	// Make sure an unspported OS returns an error (instead of unkown behavior)
+	supportedOS = "unknown"
+	Timeout = 10 * time.Second
+	MinimumEntropy = 128
+	err = WaitForEntropy()
+	if err == nil {
+		t.Error("Should get error when using unknown OS")
+	}
+
 }