Improving option comment and test coverage.

widgets/linechart/linechart.go

@@ -376,7 +376,7 @@ func (lc *LineChart) drawSeries(cvs *canvas.Canvas, xd *axes.XDetails, yd *axes.
 		// Skip over series that don't have at least two points since we can't
 		// draw a line for just one point.
 		// Skip over series that fall under the minimum value on the X axis.
-		if got := len(sv.values); got <= 1 || got < int(xdForCap.Scale.Min.Value) {
+		if got := len(sv.values); got <= 1 {
 			continue
 		}
 

widgets/linechart/linechart_test.go

@@ -133,6 +133,33 @@ func TestLineChartDraws(t *testing.T) {
 				return ft
 			},
 		},
+		{
+			desc:   "empty with just one point",
+			canvas: image.Rect(0, 0, 3, 4),
+			writes: func(lc *LineChart) error {
+				return lc.Series("first", []float64{1})
+			},
+			wantCapacity: 2,
+			want: func(size image.Point) *faketerm.Terminal {
+				ft := faketerm.MustNew(size)
+				c := testcanvas.MustNew(ft.Area())
+
+				// Y and X axis.
+				lines := []draw.HVLine{
+					{Start: image.Point{1, 0}, End: image.Point{1, 2}},
+					{Start: image.Point{1, 2}, End: image.Point{2, 2}},
+				}
+				testdraw.MustHVLines(c, lines)
+
+				// Value labels.
+				testdraw.MustText(c, "…", image.Point{0, 0})
+				testdraw.MustText(c, "0", image.Point{0, 1})
+				testdraw.MustText(c, "0", image.Point{2, 3})
+
+				testcanvas.MustApply(c, ft)
+				return ft
+			},
+		},
 		{
 			desc:   "sets axes cell options",
 			canvas: image.Rect(0, 0, 3, 4),

widgets/linechart/options.go

@@ -151,10 +151,11 @@ func YAxisCustomScale(min, max float64) Option {
 
 // XAxisUnscaled when provided, stops the LineChart from rescaling the X axis
 // when it can't fit all the values in the series, instead the LineCharts only
-// displays the last n values that fit into its width. This results in hiding
-// some values from the beginning of the series that didn't fit completely and
-// might hide some shorter series as this effectively maked the X axis start at
-// a non-zero value.
+// displays the last n values that fit into its width. This is useful to create
+// an impression of values rolling through the linechart right to left. Note
+// that this results in hiding of values from the beginning of the series
+// that didn't fit completely and might hide some shorter series as this
+// effectively makes the X axis start at a non-zero value.
 //
 // The default behavior is to rescale the X axis to display all the values.
 // This option takes no effect if all the values on the series fit into the