Be more strict about what constitutes a valid NamespacedKey

* Brings us largely in line with what is supported by the implementation
* Adds unit tests

By: md_5 <git@md-5.net>

paper-api/src/main/java/org/bukkit/NamespacedKey.java

@@ -3,11 +3,19 @@ package org.bukkit;
 import com.google.common.base.Preconditions;
 import java.util.Locale;
 import java.util.UUID;
+import java.util.regex.Pattern;
 import org.bukkit.plugin.Plugin;
 
 /**
  * Represents a String based key which consists of two components - a namespace
  * and a key.
+ *
+ * Namespaces may only contain lowercase alphanumeric characters, periods,
+ * underscores, and hyphens.
+ * <p>
+ * Keys may only contain lowercase alphanumeric characters, periods,
+ * underscores, hyphens, and forward slashes.
+ *
  */
 public final class NamespacedKey {
 
@@ -21,6 +29,9 @@ public final class NamespacedKey {
      */
     public static final String BUKKIT = "bukkit";
     //
+    private static final Pattern VALID_NAMESPACE = Pattern.compile("[a-z0-9._-]+");
+    private static final Pattern VALID_KEY = Pattern.compile("[a-z0-9/._-]+");
+    //
     private final String namespace;
     private final String key;
 
@@ -33,14 +44,13 @@ public final class NamespacedKey {
      */
     @Deprecated
     public NamespacedKey(String namespace, String key) {
-        Preconditions.checkArgument(namespace != null && !namespace.isEmpty(), "namespace");
-        Preconditions.checkArgument(key != null, "key");
+        Preconditions.checkArgument(namespace != null && VALID_NAMESPACE.matcher(namespace).matches(), "namespace");
+        Preconditions.checkArgument(key != null && VALID_KEY.matcher(key).matches(), "key");
 
         this.namespace = namespace;
         this.key = key;
 
         String string = toString();
-        Preconditions.checkArgument(string.indexOf(' ') == -1, "NamespacedKey cannot contain spaces (%s)", string);
         Preconditions.checkArgument(string.length() < 256, "NamespacedKey must be less than 256 characters", string);
     }
 
@@ -54,12 +64,13 @@ public final class NamespacedKey {
         Preconditions.checkArgument(plugin != null, "plugin");
         Preconditions.checkArgument(key != null, "key");
 
-        // Plugin names cannot have spaces anymore (SimplePluginManager)
-        Preconditions.checkArgument(key.indexOf(' ') == -1, "key cannot contain spaces (%s)", key);
-
         this.namespace = plugin.getName().toLowerCase(Locale.ROOT);
         this.key = key.toLowerCase().toLowerCase(Locale.ROOT);
 
+        // Check validity after normalization
+        Preconditions.checkArgument(VALID_NAMESPACE.matcher(namespace).matches(), "namespace");
+        Preconditions.checkArgument(VALID_KEY.matcher(key).matches(), "key");
+
         String string = toString();
         Preconditions.checkArgument(string.length() < 256, "NamespacedKey must be less than 256 characters (%s)", string);
     }

paper-api/src/test/java/org/bukkit/NamespacedKeyTest.java

@@ -0,0 +1,49 @@
+package org.bukkit;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class NamespacedKeyTest {
+
+    @Test
+    public void testValid() {
+        Assert.assertEquals("minecraft:foo", new NamespacedKey("minecraft", "foo").toString());
+        Assert.assertEquals("minecraft:foo/bar", new NamespacedKey("minecraft", "foo/bar").toString());
+        Assert.assertEquals("minecraft:foo/bar_baz", new NamespacedKey("minecraft", "foo/bar_baz").toString());
+        Assert.assertEquals("minecraft:foo/bar_baz-qux", new NamespacedKey("minecraft", "foo/bar_baz-qux").toString());
+        Assert.assertEquals("minecraft:foo/bar_baz-qux.quux", new NamespacedKey("minecraft", "foo/bar_baz-qux.quux").toString());
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testEmptyNamespace() {
+        new NamespacedKey("", "foo").toString();
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testEmptyKey() {
+        new NamespacedKey("minecraft", "").toString();
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testInvalidNamespace() {
+        new NamespacedKey("minecraft/test", "foo").toString();
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testInvalidKey() {
+        new NamespacedKey("minecraft", "foo!").toString();
+    }
+
+    @Test
+    public void testBelowLength() {
+        new NamespacedKey("loremipsumdolorsitametconsecteturadipiscingelitduisvolutpatvelitsitametmaximusscelerisquemorbiullamcorperexacconsequategestas",
+                "loremipsumdolorsitametconsecteturadipiscingelitduisvolutpatvelitsitametmaximusscelerisquemorbiullamcorperexacconsequategestas").toString();
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testAboveLength() {
+        new NamespacedKey("loremipsumdolorsitametconsecteturadipiscingelitduisvolutpatvelitsitametmaximusscelerisquemorbiullamcorperexacconsequategestas",
+                "loremipsumdolorsitametconsecteturadipiscingelitduisvolutpatvelitsitametmaximusscelerisquemorbiullamcorperexacconsequategestas/"
+                + "loremipsumdolorsitametconsecteturadipiscingelitduisvolutpatvelitsitametmaximusscelerisquemorbiullamcorperexacconsequategestas").toString();
+    }
+}