Document code, make variable names more descriptive.

Author: jamestalmage

lib/reporters/mini.js

@@ -15,8 +15,8 @@ function MiniReporter() {
 	this.skipCount = 0;
 	this.rejectionCount = 0;
 	this.exceptionCount = 0;
-	this.lastWritten = '';
-	this.prevLineCount = 0;
+	this.currentStatus = '';
+	this.statusLineCount = 0;
 	this.stream = lastLineStream(process.stderr);
 }
 
@@ -136,9 +136,9 @@ MiniReporter.prototype.finish = function () {
 
 MiniReporter.prototype.write = function (str) {
 	cliCursor.hide();
-	this.lastWritten = str + '\n';
+	this.currentStatus = str + '\n';
 	this._update();
-	this.prevLineCount = this.lastWritten.split('\n').length;
+	this.statusLineCount = this.currentStatus.split('\n').length;
 };
 
 MiniReporter.prototype.stdout = MiniReporter.prototype.stderr = function (data) {
@@ -147,11 +147,15 @@ MiniReporter.prototype.stdout = MiniReporter.prototype.stderr = function (data)
 
 MiniReporter.prototype._update = function (data) {
 	var str = '';
-	var ct = this.prevLineCount;
+	var ct = this.statusLineCount;
 	var columns = process.stdout.columns;
 	var lastLine = this.stream.lastLine;
+
+	// Terminals will automatically wrap to a new line if text exceed the column width.
+	// We want what is (visually) the last line of output. Not everything after the last `\n` character.
 	lastLine = lastLine.substring(lastLine.length - (lastLine.length % columns));
 
+	// Unless the last line of logOutput is completely empty, we need to delete it and rewrite it.
 	if (lastLine.length) {
 		ct++;
 	}
@@ -161,37 +165,43 @@ MiniReporter.prototype._update = function (data) {
 	str += lastLine;
 
 	if (str.length) {
+		// `push`ing to the stream is the equivalent to a `write`, but `lastLine` is not updated.
 		this.stream.push(str);
 	}
 
 	if (data) {
 		this.stream.write(data);
 	}
 
-	var lastWritten = this.lastWritten;
-	if (lastWritten.length) {
+	var currentStatus = this.currentStatus;
+	if (currentStatus.length) {
 		lastLine = this.stream.lastLine;
+		// We need a newline between the last line of the log output and the status message.
+		// However, if the last line of the log output is the exact width of the terminal,
+		// a newline is already implied, and adding a second will cause problems.
 		if (lastLine.length % columns) {
-			lastWritten = '\n' + lastWritten;
+			currentStatus = '\n' + currentStatus;
 		}
-		this.stream.push(lastWritten);
+		// Writes the status message, without affecting the `lastLine` status.
+		this.stream.push(currentStatus);
 	}
 };
 
 // TODO(@jamestalamge): This should be fixed in log-update and ansi-escapes once we are confident it's a good solution.
 var CSI = '\u001b[';
 var ERASE_LINE = CSI + '2K';
-var CURSOR_LEFT = CSI + '0G';
+var CURSOR_TO_COLUMN_0 = CSI + '0G';
 var CURSOR_UP = CSI + '1A';
 
+// Erases `count` lines from the end of the terminal.
 function eraseLines(count) {
 	var clear = '';
 
 	for (var i = 0; i < count; i++) {
 		clear += ERASE_LINE + (i < count - 1 ? CURSOR_UP : '');
 	}
 	if (count) {
-		clear += CURSOR_LEFT;
+		clear += CURSOR_TO_COLUMN_0;
 	}
 
 	return clear;