throw new AssertionError(e);
    }
  }

  private static final Appendable NASTY_APPENDABLE =
      new Appendable() {
        @Override
        public Appendable append(@Nullable CharSequence csq) throws IOException {
          throw new IOException();
        }

        @Override
        public Appendable append(@Nullable CharSequence csq, int start, int end)
            throws IOException {

      }
    };
  }

  static Appendable separatingAppendable(
      Appendable delegate, String separator, int afterEveryChars) {
    checkNotNull(delegate);
    checkNotNull(separator);
    checkArgument(afterEveryChars > 0);
    return new Appendable() {
      int charsUntilSeparator = afterEveryChars;

      @Override
      public Appendable append(char c) throws IOException {

forceFetch(java.io.File, java.net.URI); } org/gradle/wrapper/Logger.class package org.gradle.wrapper; public final class Logger implements Appendable { public final boolean quiet; public void Logger(boolean); public final void log(String); public final Appendable append(CharSequence); public final Appendable append(CharSequence, int, int); public final Appendable append(char); } org/gradle/wrapper/PathAssembler.class package org.gradle.wrapper; public final class PathAssembler { public void PathAs...

  }

  public <T extends Readable & Appendable> void testMultiBound() {
    assertAssignable(new TypeToken<List<T>>() {}, new TypeToken<List<? extends Readable>>() {});
    assertAssignable(new TypeToken<List<T>>() {}, new TypeToken<List<? extends Appendable>>() {});
  }

  public void testToGenericType() {

  }

  public <T extends Readable & Appendable> void testMultiBound() {
    assertAssignable(new TypeToken<List<T>>() {}, new TypeToken<List<? extends Readable>>() {});
    assertAssignable(new TypeToken<List<T>>() {}, new TypeToken<List<? extends Appendable>>() {});
  }

  public void testToGenericType() {

    assertThat(ArbitraryInstances.get(Appendable.class).toString()).isEmpty();
    assertThat(ArbitraryInstances.get(StringBuilder.class).toString()).isEmpty();
    assertThat(ArbitraryInstances.get(StringBuffer.class).toString()).isEmpty();
    assertFreshInstanceReturned(
        ArrayList.class,
        HashMap.class,
        Appendable.class,
        StringBuilder.class,
        StringBuffer.class,

    assertThat(ArbitraryInstances.get(Appendable.class).toString()).isEmpty();
    assertThat(ArbitraryInstances.get(StringBuilder.class).toString()).isEmpty();
    assertThat(ArbitraryInstances.get(StringBuffer.class).toString()).isEmpty();
    assertFreshInstanceReturned(
        ArrayList.class,
        HashMap.class,
        Appendable.class,
        StringBuilder.class,
        StringBuffer.class,

  @AndroidIncompatible // problem with equality of Type objects?
  public void testFreshInstance() {
    assertFreshInstances(
        String.class,
        CharSequence.class,
        Appendable.class,
        StringBuffer.class,
        StringBuilder.class,
        Pattern.class,
        MatchResult.class,
        Number.class,
        int.class,
        Integer.class,
        long.class,

  @AndroidIncompatible // problem with equality of Type objects?
  public void testFreshInstance() {
    assertFreshInstances(
        String.class,
        CharSequence.class,
        Appendable.class,
        StringBuffer.class,
        StringBuilder.class,
        Pattern.class,
        MatchResult.class,
        Number.class,
        int.class,
        Integer.class,
        long.class,

Let's see a very simple example. It will be so simple that it is not very useful, for now.

But this way we can focus on how the **Dependency Injection** system works.

### Create a dependency, or "dependable" { #create-a-dependency-or-dependable }

Let's first focus on the dependency.

It is just a function that can take all the same parameters that a *path operation function* can take: