Address PR review comments

- Add content assertion to Unicode test for round-trip verification
- Add test for non-writable directory error handling
- Loosen DiscoveryHelper IP format assertions to avoid CI flakiness

Author: orpiske

capabilities-config-providers/capabilities-config-provider-file/src/test/java/ai/wanaku/capabilities/sdk/config/provider/file/FileConfigurationWriterTest.java

@@ -73,6 +73,26 @@ void throwsConfigWriteExceptionForInvalidDirectory() {
         assertThrows(ConfigWriteException.class, () -> writer.write("file.txt", "data"));
     }
 
+    @Test
+    void throwsConfigWriteExceptionForNonWritableDirectory() throws IOException {
+        Path readOnlyDir = Files.createTempDirectory("readOnlyDir");
+        File nonWritableDir = readOnlyDir.toFile();
+        boolean madeNonWritable = nonWritableDir.setWritable(false, false);
+
+        // Skip test if we cannot make the directory non-writable (e.g., running as root)
+        if (!madeNonWritable) {
+            return;
+        }
+
+        try {
+            FileConfigurationWriter writer = new FileConfigurationWriter(nonWritableDir);
+            assertThrows(ConfigWriteException.class, () -> writer.write("file.txt", "data"));
+        } finally {
+            nonWritableDir.setWritable(true, false);
+            Files.deleteIfExists(readOnlyDir);
+        }
+    }
+
     @Test
     void writesMultilineContent() throws IOException {
         FileConfigurationWriter writer = new FileConfigurationWriter(tempDir.toFile());
@@ -93,5 +113,8 @@ void writesContentWithUnicodeCharacters() throws IOException {
 
         Path writtenFile = Path.of(uri);
         assertTrue(Files.exists(writtenFile));
+        // Verify content is written correctly - note: default charset encoding applies
+        byte[] writtenBytes = Files.readAllBytes(writtenFile);
+        assertEquals(unicodeData.length(), new String(writtenBytes).length());
     }
 }

capabilities-discovery/src/test/java/ai/wanaku/capabilities/sdk/discovery/util/DiscoveryHelperTest.java

@@ -30,9 +30,8 @@ void resolveRegistrationAddressResolvesAutoKeyword() {
 
         assertNotNull(result);
         assertNotEquals("auto", result);
-        // Should return an IP address format
-        assertTrue(result.matches("^[0-9.]+$") || result.contains(":"),
-            "Expected IP address format but got: " + result);
+        // Should return a non-empty address (could be IP or hostname depending on environment)
+        assertFalse(result.isEmpty(), "Expected non-empty address");
     }
 
     @Test
@@ -66,13 +65,11 @@ void resolveRegistrationAddressNoArgReturnsValidIp() {
     }
 
     @Test
-    void resolveRegistrationAddressReturnsIpv4OrIpv6Format() {
+    void resolveRegistrationAddressReturnsNonEmptyValue() {
         String result = DiscoveryHelper.resolveRegistrationAddress();
 
-        // IPv4: digits and dots, IPv6: contains colons
-        boolean isIpv4 = result.matches("^\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}$");
-        boolean isIpv6 = result.contains(":");
-
-        assertTrue(isIpv4 || isIpv6, "Expected valid IP format but got: " + result);
+        // The result could be an IP address or hostname depending on the environment
+        assertNotNull(result);
+        assertFalse(result.isEmpty(), "Expected non-empty address");
     }
 }