The test fails on on Windows 10.
Debugging MultiLineImportFileTest just before the assertshows this:

multiLineText	String	"Multi-line comment line 1\n-- line 2\'\n/* line 3 */"
expected	String	"Multi-line comment line 1\r\n-- line 2\'\r\n/* line 3 */"

Using the system line-separator seems to be the source of the problem.