private void verifyFilePresence()

in its/core-it-support/maven-it-helper/src/main/java/org/apache/maven/it/Verifier.java [998:1084]
75 lines of code
25 McCabe index (conditional complexity)

    private void verifyFilePresence(String filePath, boolean wanted) throws VerificationException {
        if (filePath.contains("!/")) {
            Path basedir = Paths.get(getBasedir()).toAbsolutePath();
            String urlString = "jar:" + basedir.toUri().toASCIIString() + "/" + filePath;

            InputStream is = null;
            try {
                URL url = new URL(urlString);

                is = url.openStream();

                if (is == null) {
                    if (wanted) {
                        throw new VerificationException("Expected JAR resource was not found: " + filePath);
                    }
                } else {
                    if (!wanted) {
                        throw new VerificationException("Unwanted JAR resource was found: " + filePath);
                    }
                }
            } catch (MalformedURLException e) {
                throw new VerificationException("Error looking for JAR resource", e);
            } catch (IOException e) {
                if (wanted) {
                    throw new VerificationException("Error looking for JAR resource: " + filePath);
                }
            } finally {
                if (is != null) {
                    try {
                        is.close();
                    } catch (IOException e) {
                        // ignore
                    }
                }
            }
        } else {
            File expectedFile = new File(filePath);

            // NOTE: On Windows, a path with a leading (back-)slash is relative to the current drive
            if (!expectedFile.isAbsolute() && !expectedFile.getPath().startsWith(File.separator)) {
                expectedFile = new File(getBasedir(), filePath);
            }

            if (filePath.indexOf('*') > -1) {
                File parent = expectedFile.getParentFile();

                if (!parent.exists()) {
                    if (wanted) {
                        throw new VerificationException(
                                "Expected file pattern was not found: " + expectedFile.getPath());
                    }
                } else {
                    String shortNamePattern = expectedFile.getName().replaceAll("\\*", ".*");

                    String[] candidates = parent.list();

                    boolean found = false;

                    if (candidates != null) {
                        for (String candidate : candidates) {
                            if (candidate.matches(shortNamePattern)) {
                                found = true;
                                break;
                            }
                        }
                    }

                    if (!found && wanted) {
                        throw new VerificationException(
                                "Expected file pattern was not found: " + expectedFile.getPath());
                    } else if (found && !wanted) {
                        throw new VerificationException("Unwanted file pattern was found: " + expectedFile.getPath());
                    }
                }
            } else {
                if (!expectedFile.exists()) {
                    if (wanted) {
                        throw new VerificationException("Expected file was not found: " + expectedFile.getPath());
                    }
                } else {
                    if (!wanted) {
                        throw new VerificationException("Unwanted file was found: " + expectedFile.getPath());
                    }
                }
            }
        }
    }