Add coverage for ForeignMemoryWriterFactory (#11772)

* Add coverage for ForeignMemoryWriterFactoryTest

* test on 22+

Author: amarziali

dd-trace-core/src/test/java/datadog/trace/core/servicediscovery/ForeignMemoryWriterFactoryTest.java

@@ -0,0 +1,51 @@
+package datadog.trace.core.servicediscovery;
+
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.mockito.Mockito.mockStatic;
+
+import datadog.environment.JavaVirtualMachine;
+import datadog.environment.OperatingSystem;
+import org.junit.jupiter.api.Assumptions;
+import org.mockito.MockedStatic;
+import org.tabletest.junit.TableTest;
+
+class ForeignMemoryWriterFactoryTest {
+
+  @TableTest({
+    "scenario           | osType  | architecture | javaAtLeast22 | expectedClassFragment",
+    "macOS              | MACOS   | X64          | false         |                      ",
+    "Windows            | WINDOWS | X64          | false         |                      ",
+    "Linux unknown arch | LINUX   | UNKNOWN      | false         |                      ",
+    "Linux pre-Java22   | LINUX   | X64          | false         | JNA                  ",
+    "Linux Java22+      | LINUX   | X64          | true          | FFM                  "
+  })
+  void get(
+      String scenario,
+      String osType,
+      String architecture,
+      boolean javaAtLeast22,
+      String expectedClassFragment) {
+    // MemFDUnixWriterFFM uses java.lang.foreign and will fail to load on pre-22 JVMs
+    boolean realJavaAtLeast22 = JavaVirtualMachine.isJavaVersionAtLeast(22);
+    Assumptions.assumeTrue(!javaAtLeast22 || realJavaAtLeast22, "FFM writer requires Java 22+");
+    try (MockedStatic<OperatingSystem> osMock = mockStatic(OperatingSystem.class);
+        MockedStatic<JavaVirtualMachine> jvmMock = mockStatic(JavaVirtualMachine.class)) {
+      osMock.when(OperatingSystem::type).thenReturn(OperatingSystem.Type.valueOf(osType));
+      osMock
+          .when(OperatingSystem::architecture)
+          .thenReturn(OperatingSystem.Architecture.valueOf(architecture));
+      jvmMock.when(() -> JavaVirtualMachine.isJavaVersionAtLeast(22)).thenReturn(javaAtLeast22);
+
+      ForeignMemoryWriter writer = new ForeignMemoryWriterFactory().get();
+
+      if (expectedClassFragment == null) {
+        assertNull(writer, scenario);
+      } else {
+        assertNotNull(writer, scenario);
+        assertTrue(writer.getClass().getName().contains(expectedClassFragment), scenario);
+      }
+    }
+  }
+}

dd-trace-core/src/test/resources/mockito-extensions/org.mockito.plugins.MockMaker

@@ -0,0 +1 @@
+mock-maker-inline