From b539a3e67f53166e4323dae9293b3c75a35c00eb Mon Sep 17 00:00:00 2001
From: Marek Urbaniak <8502071+marekoid@users.noreply.github.com>
Date: Mon, 30 Mar 2020 19:03:21 +0100
Subject: [PATCH 1/3] Add precondition check util

---
 .../client/crypto/nacl/SecretBoxOpener.java   | 14 +++++------
 .../client/util/internal/Preconditions.java   | 23 +++++++++++++++++++
 2 files changed, 29 insertions(+), 8 deletions(-)
 create mode 100644 src/main/java/com/pusher/client/util/internal/Preconditions.java

diff --git a/src/main/java/com/pusher/client/crypto/nacl/SecretBoxOpener.java b/src/main/java/com/pusher/client/crypto/nacl/SecretBoxOpener.java
index fb2ecb04..5bf212bc 100644
--- a/src/main/java/com/pusher/client/crypto/nacl/SecretBoxOpener.java
+++ b/src/main/java/com/pusher/client/crypto/nacl/SecretBoxOpener.java
@@ -24,6 +24,9 @@ a copy of this software and associated documentation files (the "Software"),
 
 package com.pusher.client.crypto.nacl;
 
+import static com.pusher.client.util.internal.Preconditions.checkArgument;
+import static com.pusher.client.util.internal.Preconditions.checkNotNull;
+
 import java.util.Arrays;
 
 public class SecretBoxOpener {
@@ -33,19 +36,14 @@ public class SecretBoxOpener {
     private byte[] key;
 
     public SecretBoxOpener(byte[] key) {
-        // TODO: add a a little preconditions lib/class for that
-        if (key == null) throw new IllegalArgumentException("null key passed");
-        if (key.length != 32) {
-            throw new IllegalArgumentException("key should be 32B, is: " + key.length + "B");
-        }
+        checkNotNull(key, "null key passed");
+        checkArgument(key.length == 32, "key should be 32B, is: " + key.length + "B");
 
         this.key = key;
     }
 
     public byte[] open(byte box[], byte nonce[]) throws AuthenticityException {
-        if (key == null) {
-            throw new IllegalStateException("key has been cleared, create new instance");
-        }
+        checkNotNull(key, "key has been cleared, create new instance");
 
         byte subKey[] = new byte[32];
         byte counter[] = new byte[16];
diff --git a/src/main/java/com/pusher/client/util/internal/Preconditions.java b/src/main/java/com/pusher/client/util/internal/Preconditions.java
new file mode 100644
index 00000000..9841efe4
--- /dev/null
+++ b/src/main/java/com/pusher/client/util/internal/Preconditions.java
@@ -0,0 +1,23 @@
+package com.pusher.client.util.internal;
+
+public class Preconditions {
+
+    public static void checkArgument(boolean expression, Object errorMessage) {
+        if (!expression) {
+            throw new IllegalArgumentException(String.valueOf(errorMessage));
+        }
+    }
+
+    public static void checkState(boolean expression, Object errorMessage) {
+        if (!expression) {
+            throw new IllegalStateException(String.valueOf(errorMessage));
+        }
+    }
+
+    public static <T> T checkNotNull(T reference, Object errorMessage) {
+        if (reference == null) {
+            throw new NullPointerException(String.valueOf(errorMessage));
+        }
+        return reference;
+    }
+}

From dbdea4e53d468051462e3e7480e7a0a5368d174d Mon Sep 17 00:00:00 2001
From: Marek Urbaniak <8502071+marekoid@users.noreply.github.com>
Date: Tue, 31 Mar 2020 11:41:38 +0100
Subject: [PATCH 2/3] Alter precondition failure massage

Per feedback:
https://github.com/pusher/pusher-websocket-java/pull/240/files#r400806116
---
 .../java/com/pusher/client/crypto/nacl/SecretBoxOpener.java    | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/main/java/com/pusher/client/crypto/nacl/SecretBoxOpener.java b/src/main/java/com/pusher/client/crypto/nacl/SecretBoxOpener.java
index 5bf212bc..32048f73 100644
--- a/src/main/java/com/pusher/client/crypto/nacl/SecretBoxOpener.java
+++ b/src/main/java/com/pusher/client/crypto/nacl/SecretBoxOpener.java
@@ -37,7 +37,8 @@ public class SecretBoxOpener {
 
     public SecretBoxOpener(byte[] key) {
         checkNotNull(key, "null key passed");
-        checkArgument(key.length == 32, "key should be 32B, is: " + key.length + "B");
+        checkArgument(key.length == 32, "key length should be 32 bytes, but is " +
+                key.length + " bytes");
 
         this.key = key;
     }

From bb925cd1710e95e7e2e89f69544ce3eb738455d4 Mon Sep 17 00:00:00 2001
From: Marek Urbaniak <8502071+marekoid@users.noreply.github.com>
Date: Tue, 31 Mar 2020 12:03:10 +0100
Subject: [PATCH 3/3] Use "must" instead of "should" for precondition failure

Per feedback:
https://github.com/pusher/pusher-websocket-java/pull/240#discussion_r400816216
---
 .../java/com/pusher/client/crypto/nacl/SecretBoxOpener.java     | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/main/java/com/pusher/client/crypto/nacl/SecretBoxOpener.java b/src/main/java/com/pusher/client/crypto/nacl/SecretBoxOpener.java
index 32048f73..dd5f8a8b 100644
--- a/src/main/java/com/pusher/client/crypto/nacl/SecretBoxOpener.java
+++ b/src/main/java/com/pusher/client/crypto/nacl/SecretBoxOpener.java
@@ -37,7 +37,7 @@ public class SecretBoxOpener {
 
     public SecretBoxOpener(byte[] key) {
         checkNotNull(key, "null key passed");
-        checkArgument(key.length == 32, "key length should be 32 bytes, but is " +
+        checkArgument(key.length == 32, "key length must be 32 bytes, but is " +
                 key.length + " bytes");
 
         this.key = key;