Factor out creation of empty text face

Author: milliams

src/repr/plot.rs

@@ -182,10 +182,7 @@ impl ContinuousRepresentation for Plot {
         let face_lines = if let Some(line_style) = &self.line_style {
             unimplemented!("Text rendering does not yet support line plots")
         } else {
-            (0..face_height)
-                .map(|_| " ".repeat(face_width as usize))
-                .collect::<Vec<String>>()
-                .join("\n")
+            text_render::empty_face(face_width, face_height)
         };
         let face_points = if let Some(point_style) = &self.point_style {
             text_render::render_face_points(
@@ -197,10 +194,7 @@ impl ContinuousRepresentation for Plot {
                 &point_style,
             )
         } else {
-            (0..face_height)
-                .map(|_| " ".repeat(face_width as usize))
-                .collect::<Vec<String>>()
-                .join("\n")
+            text_render::empty_face(face_width, face_height)
         };
         text_render::overlay(&face_lines, &face_points, 0, 0)
     }

src/text_render.rs

@@ -472,6 +472,13 @@ pub fn overlay(under: &str, over: &str, x: i32, y: i32) -> String {
     out.join("\n")
 }
 
+pub fn empty_face(width: u32, height: u32) -> String {
+    (0..height)
+        .map(|_| " ".repeat(width as usize))
+        .collect::<Vec<String>>()
+        .join("\n")
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -690,4 +697,13 @@ mod tests {
         let r = "o#\n#o";
         assert_eq!(overlay(a, b, -1, -1), r);
     }
+
+    #[test]
+    fn test_empty_face() {
+        assert_eq!(empty_face(0, 0), "");
+        assert_eq!(empty_face(1, 1), " ");
+        assert_eq!(empty_face(2, 2), "  \n  ");
+        assert_eq!(empty_face(2, 3), "  \n  \n  ");
+        assert_eq!(empty_face(4, 2), "    \n    ");
+    }
 }