Basic tests for crypto wrapper functions

Even though the std lib does the heavy lifting, this should verify (somewhat) that the helper functions are working.

Better tests would involve replacing crypto/rand.Reader with a non-random Reader then comparing the contents to make sure the proper std lib crypto functions were called and their values returned.

acme/crypto_test.go

@@ -0,0 +1,48 @@
+package acme
+
+import (
+	"crypto/rand"
+	"crypto/rsa"
+	"testing"
+)
+
+func TestGeneratePrivateKey(t *testing.T) {
+	key, err := generatePrivateKey(32)
+	if err != nil {
+		t.Error("Error generating private key:", err)
+	}
+	if key == nil {
+		t.Error("Expected key to not be nil, but it was")
+	}
+}
+
+func TestGenerateCSR(t *testing.T) {
+	key, err := generatePrivateKey(512)
+	if err != nil {
+		t.Fatal("Error generating private key:", err)
+	}
+
+	csr, err := generateCsr(key, "fizz.buzz")
+	if err != nil {
+		t.Error("Error generating CSR:", err)
+	}
+	if csr == nil || len(csr) == 0 {
+		t.Error("Expected CSR with data, but it was nil or length 0")
+	}
+}
+
+func TestPEMEncode(t *testing.T) {
+	key, err := rsa.GenerateKey(rand.Reader, 32)
+	if err != nil {
+		t.Fatal("Error generating private key:", err)
+	}
+
+	data := pemEncode(key)
+
+	if data == nil {
+		t.Fatal("Expected result to not be nil, but it was")
+	}
+	if len(data) != 127 {
+		t.Errorf("Expected PEM encoding to be length 127, but it was %d", len(data))
+	}
+}