private static <T> void setImplementation(Class<T> type, Class<? extends T> implementation) {
    checkArgument(type != implementation, "Don't register %s to itself!", type);
    checkArgument(
        !DEFAULTS.containsKey(type), "A default value was already registered for %s", type);
    checkArgument(
        implementations.put(type, implementation) == null,
        "Implementation for %s was already registered",

 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.testing;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Throwables.throwIfUnchecked;
import static junit.framework.Assert.assertEquals;
import static junit.framework.Assert.fail;

public class PreconditionsTest extends TestCase {
  public void testCheckArgument_simple_success() {
    checkArgument(true);
  }

  public void testCheckArgument_simple_failure() {
    assertThrows(IllegalArgumentException.class, () -> checkArgument(false));
  }

  public void testCheckArgument_simpleMessage_success() {
    checkArgument(true, IGNORE_ME);
  }

  public void testCheckArgument_simpleMessage_failure() {

      long loadSuccessCount,
      long loadExceptionCount,
      long totalLoadTime,
      long evictionCount) {
    checkArgument(hitCount >= 0);
    checkArgument(missCount >= 0);
    checkArgument(loadSuccessCount >= 0);
    checkArgument(loadExceptionCount >= 0);
    checkArgument(totalLoadTime >= 0);
    checkArgument(evictionCount >= 0);

    this.hitCount = hitCount;
    this.missCount = missCount;

      long loadSuccessCount,
      long loadExceptionCount,
      long totalLoadTime,
      long evictionCount) {
    checkArgument(hitCount >= 0);
    checkArgument(missCount >= 0);
    checkArgument(loadSuccessCount >= 0);
    checkArgument(loadExceptionCount >= 0);
    checkArgument(totalLoadTime >= 0);
    checkArgument(evictionCount >= 0);

    this.hitCount = hitCount;
    this.missCount = missCount;

 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.common.io;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkPositionIndexes;
import static java.lang.Math.min;
import static java.util.Objects.requireNonNull;

 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.common.reflect;

import static com.google.common.base.Preconditions.checkArgument;

import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;
import org.jspecify.annotations.Nullable;

/**
 * Captures a free type variable that can be used in {@link TypeToken#where}. For example:

          Class<?>[] parameterTypes = method.getParameterTypes();
          checkArgument(
              parameterTypes.length == 1,
              "Method %s has @Subscribe annotation but has %s parameters. "
                  + "Subscriber methods must have exactly 1 parameter.",
              method,
              parameterTypes.length);

          checkArgument(
              !parameterTypes[0].isPrimitive(),

  }

  /**
   * Ensures the truth of an expression involving one or more parameters to the calling method.
   *
   * <p>See {@link #checkArgument(boolean, String, Object...)} for details.
   *
   * @since 20.0 (varargs overload since 2.0)
   */
  public static void checkArgument(boolean expression, String errorMessageTemplate, char p1) {
    if (!expression) {

  }

  @VisibleForTesting
  static void checkExceptionClassValidity(Class<? extends Exception> exceptionClass) {
    checkArgument(
        isCheckedException(exceptionClass),
        "Futures.getChecked exception type (%s) must not be a RuntimeException",
        exceptionClass);
    checkArgument(
        hasConstructorUsableByGetChecked(exceptionClass),