Add unit tests for tls-server-name functionality

Co-authored-by: brendandburns <[email protected]>

Author: Copilot

util/src/test/java/io/kubernetes/client/util/ClientBuilderTest.java

@@ -48,6 +48,8 @@ class ClientBuilderTest {
       Resources.getResource("kubeconfig-https").getPath();
   private static final String KUBECONFIG_HTTPS_X509_FILE_PATH =
       Resources.getResource("kubeconfig-https-x509").getPath();
+  private static final String KUBECONFIG_TLS_SERVER_NAME_FILE_PATH =
+      Resources.getResource("kubeconfig-tls-server-name").getPath();
   private static final String SSL_CA_CERT_PATH =
       new File(Resources.getResource("ca-cert.pem").getPath()).toString();
   private static final String INVALID_SSL_CA_CERT_PATH =
@@ -321,4 +323,22 @@ void detectsServerNotSet() {
           ClientBuilder.kubeconfig(kubeConfigWithoutServer);
         }).hasMessage("No server in kubeconfig").isInstanceOf(IllegalArgumentException.class);
   }
+
+  @Test
+  void tlsServerNameSetFromKubeConfig() throws IOException {
+    ApiClient client =
+        ClientBuilder.kubeconfig(
+                KubeConfig.loadKubeConfig(new FileReader(KUBECONFIG_TLS_SERVER_NAME_FILE_PATH)))
+            .build();
+    assertThat(client.getTlsServerName()).isEqualTo("my-cluster.example.com");
+  }
+
+  @Test
+  void tlsServerNameNotSetWhenNotInKubeConfig() throws IOException {
+    ApiClient client =
+        ClientBuilder.kubeconfig(
+                KubeConfig.loadKubeConfig(new FileReader(KUBECONFIG_HTTPS_FILE_PATH)))
+            .build();
+    assertThat(client.getTlsServerName()).isNull();
+  }
 }

util/src/test/java/io/kubernetes/client/util/KubeConfigTest.java

@@ -425,4 +425,35 @@ void execCredentialsCertificate() {
     assertThat(kc.getCredentials()).containsEntry(KubeConfig.CRED_CLIENT_KEY_DATA_KEY, "key");
     assertThat(kc.getCredentials().get(KubeConfig.CRED_TOKEN_KEY)).isNull();
   }
+
+  @Test
+  void tlsServerName() {
+    String configWithTlsServerName =
+        "apiVersion: v1\n"
+            + "clusters:\n"
+            + "- cluster:\n"
+            + "    server: https://192.168.1.1:6443\n"
+            + "    tls-server-name: my-cluster.example.com\n"
+            + "    certificate-authority-data: dGVzdAo=\n"
+            + "  name: test-cluster\n"
+            + "users:\n"
+            + "- user:\n"
+            + "    token: test-token\n"
+            + "  name: test-user\n"
+            + "contexts:\n"
+            + "- context:\n"
+            + "    cluster: test-cluster\n"
+            + "    user: test-user\n"
+            + "  name: test-context\n"
+            + "current-context: test-context\n";
+
+    KubeConfig config = KubeConfig.loadKubeConfig(new StringReader(configWithTlsServerName));
+    assertThat("my-cluster.example.com").isEqualTo(config.getTlsServerName());
+  }
+
+  @Test
+  void tlsServerNameNotPresent() {
+    KubeConfig config = KubeConfig.loadKubeConfig(new StringReader(KUBECONFIG_TOKEN));
+    assertThat(config.getTlsServerName()).isNull();
+  }
 }

util/src/test/resources/kubeconfig-tls-server-name

@@ -0,0 +1,17 @@
+apiVersion: v1
+clusters:
+  - cluster:
+      server: https://192.168.1.1:6443
+      tls-server-name: my-cluster.example.com
+      certificate-authority-data: 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
+    name: test-cluster
+users:
+  - user:
+      token: test-token
+    name: test-user
+contexts:
+  - context:
+      cluster: test-cluster
+      user: test-user
+    name: test-context
+current-context: test-context