This 3 args-per-commit syntax is obtuse.  I would prefer to be a bit more declarative within the test, at the expense of slightly more framework to implement the test.

Either inline the assertions for c, b, a in the test, or setup something that lets you describe the values, e.g.:

  private TestList expected;

  expected.row(c).lane(0).parent(b);
  expected.row(b).lane(0).parent(a);
  expected.row(a).lane(0);
  assertCommitList(pcl);