src/main/java/org/fest/assertions/internal/Files.java
public void assertEqualContent(Description description, File actual, File expected, Charset charset) {
    checkIsFile(expected);
    checkNotNull(charset);
    assertIsFile(description, actual);
    try {
      String lineSeparator = System.getProperty("line.separator");
      FileDiffs diffs = comparator.compareContents(actual, expected, charset);
      if (!diffs.isEmpty()) {
        String format = "files expected:<%s> and actual:<%s> do not have equal content:" + lineSeparator + "%s"
            + lineSeparator + "using charset:<%s>";
        throw failures.failure(description, new BasicErrorMessageFactory(format, expected, actual, diffs, charset));
      }
    } catch (IOException e) {
      String format = "Failed to compare contents of files:<%s> and:<%s> using charset:<%s>";
      throw new IORuntimeException(String.format(format, actual, expected, charset), e);
    }
  }
public void assertEqualContent(Description description, File actual, File expected, Charset charset) {
    checkIsFile(expected);
    checkNotNull(charset);
    assertIsFile(description, actual);
    try {
      String lineSeparator = System.getProperty("line.separator");
      FileDiffs diffs = comparator.compareContents(actual, expected, charset);
      if (!diffs.isEmpty()) {
        String format = "files expected:<%s> and actual:<%s> do not have equal content:" + lineSeparator + "%s"
            + lineSeparator + "using charset:<%s>";
        throw failures.failure(description, new BasicErrorMessageFactory(format, expected, actual, diffs, charset));
      }
    } catch (IOException e) {
      String format = "Failed to compare contents of files:<%s> and:<%s> using charset:<%s>";
      throw new IORuntimeException(String.format(format, actual, expected, charset), e);
    }
  }
Asserts that the given {@code File}s represent existing files with equal content. It is assumed that the content of
the files is text.

@param description the description of the <em>actual</em> {@code File}.
@param actual the <em>actual</em> {@code File}.
@param expected the <em>expected</em> {@code File}.
@param charset the charset to use when reading the contents of the given {@code File}s.
@throws NullPointerException if the <em>expected</em> {@code File} is {@code null}.
@throws IllegalArgumentException if the <em>expected</em> {@code File} does not represent an existing file.
@throws NullPointerException if the given charset is {@code null}.
@throws AssertionError if the <em>actual</em> {@code File} is {@code null}.
@throws AssertionError if the <em>actual</em> {@code File} does not represent an existing file.
@throws IORuntimeException if an I/O error occurs.
@throws AssertionError if the given files do not have equal content.