Add tests to verify provider registration utility functions.

For reference, here's the initial set of providers:

```
[SUN, SunRsaSign, SunEC, SunJSSE, SunJCE, SunJGSS, SunSASL, XMLDSig, SunPCSC, JdkLDAP, JdkSASL, SunPKCS11]
```

Versus the list after executing `installOnlyOpenJDKProviders()`:

```
[SUN, SunJCE, SunRsaSign, SunEC]
```

Note that the OpenJDK providers are initially present but in a different order, which is used convey provider preference.

NOKEYCHECK=True
PiperOrigin-RevId: 568645228

2 files changed, 65 insertions, 0 deletions

diff --git a/BUILD.bazel b/BUILD.bazel
index 54addd2..dd5c889 100644
--- a/BUILD.bazel
+++ b/BUILD.bazel
@@ -20,6 +20,17 @@ java_library(
     ],
 )
 
+java_test(
+    name = "TestUtilTest",
+    size = "small",
+    srcs = ["java/com/google/security/wycheproof/TestUtilTest.java"],
+    test_class = "com.google.security.wycheproof.TestUtilTest",
+    deps = [
+        ":utils",
+        "@junit",
+    ],
+)
+
 common_deps = [
     ":utils",
     "@com_google_code_gson_gson",
diff --git a/java/com/google/security/wycheproof/TestUtilTest.java b/java/com/google/security/wycheproof/TestUtilTest.java
new file mode 100644
index 0000000..a920de8
--- /dev/null
+++ b/java/com/google/security/wycheproof/TestUtilTest.java
@@ -0,0 +1,54 @@
+/**
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ *
+ * <p>http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * <p>Unless required by applicable law or agreed to in writing, software distributed under the
+ * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.security.wycheproof;
+
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertTrue;
+
+import java.security.Provider;
+import java.security.Security;
+import java.util.ArrayList;
+import java.util.List;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/** Tests the test utilities. */
+@RunWith(JUnit4.class)
+public final class TestUtilTest {
+
+  private static List<String> getProviders() {
+    List<String> providerNames = new ArrayList<>();
+    for (Provider p : Security.getProviders()) {
+      providerNames.add(p.getName());
+    }
+    return providerNames;
+  }
+
+  @Test
+  public void removeAllProviders_succeeds() throws Exception {
+    TestUtil.removeAllProviders();
+
+    assertTrue("List of providers is not empty", getProviders().isEmpty());
+  }
+
+  @Test
+  public void installOnlyOpenJDKProviders_correctOrder() throws Exception {
+    TestUtil.installOnlyOpenJDKProviders();
+
+    String[] expectedProviders = {"SUN", "SunJCE", "SunRsaSign", "SunEC"};
+    assertArrayEquals(
+        "Expected providers not present and/or not in order",
+        getProviders().toArray(),
+        expectedProviders);
+  }
+}