Write("") followed by NewLine() leaves a tab on the blank line and drops the next line to column 0 (the #115 fix misses empty writes) #126

What's wrong

Writing an empty string with Write("") (or Write(null)) and then calling NewLine() puts the indentation on the blank line instead of on the next line. Every line after that starts at column 0.

var cb = CodeBlocker.Create();
cb.WriteLine("class C");
using (new Scope(cb))
{
    cb.WriteLine("int a;");
    cb.Write("");      // e.g. an optional modifier that happens to be empty
    cb.NewLine();
    cb.WriteLine("int b;");
}

Observed output, with → standing for a tab:

class C
{
→int a;
→
int b;
}

Expected output:

class C
{
→int a;

→int b;
}

I reproduced this against the current main project, and the existing test suite passes.

Cause

There are two pieces involved (CodeBlocker/CodeBlocker.cs):

• Write, around lines 254–261: it forwards to IndentedTextWriter.Write(string). That method always writes the pending tabs and clears its tabs-pending flag, even when the string is empty or null. Write only sets isMidLine when the text is non-empty.
• NewLine(), around lines 219–232: because isMidLine is false, it takes the WriteLineNoTabs branch. That branch does not re-arm the pending tabs.

The tabs are already spent on the blank line, so the next WriteLine gets none. This is the same failure #115 fixed for non-empty partial writes. The empty-string path was left out of that fix.

Why it matters

Generators often build a line from optional fragments (modifiers, attributes, a separator) that can be empty. When that happens, the output silently gets a trailing-whitespace line and everything after it in the scope loses its indentation. Nothing fails. The generated code is just mis-formatted, and snapshot tests show unrelated diffs.

Suggested fix / acceptance criteria

• In Write, return early when string.IsNullOrEmpty(text), so the underlying writer never consumes the pending tabs. Alternatively, set isMidLine = true after every call that reaches the inner writer.
• Add a test next to the NewLine() after a partial Write() makes the next line lose its indentation (also breaks expression bodies that start with a blank line) #115 regression test: Write("") + NewLine() + WriteLine("x") inside a scope produces an empty line followed by an indented x. Cover Write(null) as well.