Different newlines on Windows

[prdoyle]

Summary

WIndows has trouble with newlines and I'm not sure how you want to proceed.

Failure

When I run JfrSchemaFactoryTest.canRunSimpleSelectFromClassLoad on Windows, it fails on column 2 because the newlines are different:

assertThat(rs.getString(2)).isEqualTo("""
        {
          classLoader = null
          name = "java/lang/Throwable"
          package = {
            name = "java/lang"
            module = {
              name = "java.base"
              version = "17"
              location = "jrt:/java.base"
              classLoader = null
            }
            exported = true
          }
          modifiers = 33
          hidden = false
        }
        """);

Cause

JfrSchema.getConverter is using the following converter:

else if (field.getTypeName().equals("java.lang.Class")) {
    LOGGER.log(INFO, "| -> java.lang.Class");
    return event -> event.getClass(field.getName());
}

I believe when the testcase calls rs.getString(), this is calling RecordedClass.toString() which ultimately uses StructuredWriter.lineSeparator which is initialized to String.format("%n"), and this differs by platform.

Possible solutions

Should we return the java.lang.Class in this case, rather than the RecordedClass object? The Class.toString() method should produce the same result on all platforms.

[prdoyle]

I suppose we can't necessarily get the java.lang.Class because we're running in a different JVM that might not have that class loaded.

I wonder what's the best way to deal with toString() variations across platforms, given how eager ResultSet is to call it. 🤔

[prdoyle]

I can't really find a clean way to handle this.

Facts:

1. We want our result set to contain a RecordedClass
2. ResultSet.getString calls toString
3. RecordedClass.toString is different on different platforms
4. We want the same behaviour on all platforms

One of these has to give. I hope it's 2 or 3 but I'm afraid it might have to be 1.