JUnit-import excludes non-test production code, dropping its call expressions

[Ridwanul-OpenRefactory]

CallGraphProcessor treats any file that imports org.junit.* / junit.* as a test file and excludes it from analysis before the call graph is built.
A bare import is not evidence that a file is a test - every such file is silently dropped: none of its methods are registered and so every call into it from real production code resolves to nothing - no source edge, no library edge. The call simply vanishes from the graph.

This is the general form of the problem reported in issue #66 which covers only the special case where the file's own package is org.junit/junit (i.e. JUnit itself).

---

Root cause

CallGraphProcessor.getImports (CallGraphProcessor.java) raises the flag on the import string alone:

// To cover all type of junit packages, we added these 2 conditions.
// Previously we used to maintain a list containing test packages.
if (importString.toString().startsWith("org.junit")
        || importString.toString().startsWith("junit")) {
    hasJUnitImport = true;
}

buildCallGraph, phase 1 (CallGraphProcessor.java), excludes the file outright when that flag is set - the import signal is ORed with the directory signal:

if (cgPhase == Phase.PHASE_1
        && (!ConfigurationManager.isTestRun
                && (importsPair.snd || CallGraphUtility.isUnderTestOrExampleDirectory(filePath)))) {
    CallGraphDataStructures.addFileToExcludedList(filePath);
    ...
}

We need to figure out a proper way to handle such cases where a file imports junit because such files are always excluded from call-graph creation.