File bindings/s2/unit/900-001-ob.s2 artifact 7758211977 part of check-in 9fb6fae4f8

// TODO: more output buffering tests, when i'm not so tired.
scope {
  assert 'object' === typename s2.ob;
  const ob = s2.ob;
  assert 0 === ob.level();
  assert ob === ob.push();
  print('buffered');
  var b = ob.pop(1);
  assert 0 === ob.level();
  assert b inherits s2.Buffer;
  assert b.length()>0;
  // Reminder to self: if assertion tracing is on, assertions will generate
  // output to our buffer, making exact content checks here impractical.
  // But we can do...
  assert b.toString().indexOf('buffered') >= 0;
  //print("Buffered",b.length(),"bytes.");
}

scope{
  const ob = s2.ob;
  const out = print;
  assert 1 === ob.push().level();
      out("This will be flushed to stdout.");
      ob.flush();
      out("level 1");
      var v1 = ob.takeString();
      assert ob === ob.push(100);
          out("This will be flushed to level 1.");
          ob.flush();
          out("level 2");
          var v2 = ob.takeString();
      assert ob === ob.pop();
      var v1b = ob.takeString();
      out("discarded");
      //ob.clear()// not needed b/c pop() will do this
  ob.pop();
  assert v1 === 'level 1\n';
  assert v2 === 'level 2\n';
  assert v1b.indexOf('This will be flushed to level 1.\n')>=0
    /* use indexOf() insted of === comparison because s2sh -A (assert
       tracing) breaks a direct comparison by injecting assertion
       tracing output into the buffer. */;
}

scope {
    const ob = s2.ob;
    const fHi = proc(){s2out<<"hi"};
    var v = ob.capture(fHi);
    assert "hi" === v;
    v = ob.capture("s2out<<'hi again'");
    assert "hi again" === v;
    v = ob.capture("s2out<<'hi'", 1);
    assert typeinfo(isbuffer v);
    assert "hi" === v.takeString();
    v = ob.capture(fHi, 0);
    assert undefined === v;
    const level = ob.level();
    v = ob.capture(proc(){
        s2out << "hi";
        ob.push();
        s2out << " again";
        // intentionally leaving extra entry: capture() will pop it.
    });
    assert ob.level() === level;
    assert "hi again" === v;

    const b = new s2.Buffer(/*reserving memory will bypass
                              an allocation optimization*/);
    assert b === ob.capture(eval=>{
        s2out << "hi";
        ob.push();
        s2out << " again";
    }, b);
    assert "hi again" === b.takeString();

    assert 'CWAL_RC_MISUSE' === catch ob.capture().codeString();
    assert 'CWAL_RC_MISUSE' === catch ob.capture(b).codeString()
    /* Should arguably be CWAL_RC_TYPE, but the args validation isn't
       that detailed. */;
    
    // We cannot test the too-many-ob.pop()-calls case here without
    // screwing up downstream tests.
}