Debug formatting for Style, Span, Line, Text

[joshka]

Problem

When writing some widget level code (for tui-markdown) and debugging the output of the text in tests, I found that having all fields in Style listed when they're None seemed overly verbose, and made it more difficult to navigate through any assertion errors (e.g. when taking a TDD approach to building things).

Additionally, the content field of the Span/Line/Text seems to dominate in size, as it's usually more complex than the other fields (style, alignment). This pushes them far below the start of the struct representation.

Solution

• Replace the Debug implementation of Style with one that omits any None values
• Move the content/spans/lines fields in Span/Line/Text below the other fields (this can be done easily in the struct or by manually defining a Debug implementation)
• For the various style fields, omit Some(...) surrounding the value
• Consider omitting defaults entirely

Alternatives

Write a function that provides a more custom compact debugging view of these methods:

fn compact_debug(&self) -> CompactDebugSpan {
...
}

impl Debug for CompactDebugSpan {
...
}

This doesn't work for assertions however, which use the Debug representation, so it seems like a non-starter.

Additional context

A real example from tui-markdown:

 Text {
     lines: [
         Line {
             spans: [
                 Span {
                     content: ">",
                     style: Style {
                         fg: None,
                         bg: None,
                         underline_color: None,
                         add_modifier: NONE,
                         sub_modifier: NONE,
                     },
                 },
                 Span {
                     content: " ",
                     style: Style {
                         fg: None,
                         bg: None,
                         underline_color: None,
                         add_modifier: NONE,
                         sub_modifier: NONE,
                     },
                 },
                 Span {
                     content: "Blockquote 1",
                     style: Style {
                         fg: None,
                         bg: None,
                         underline_color: None,
                         add_modifier: NONE,
                         sub_modifier: NONE,
                     },
                 },
             ],
             style: Style {
                 fg: Some(
                     Green,
                 ),
                 bg: None,
                 underline_color: None,
                 add_modifier: NONE,
                 sub_modifier: NONE,
             },
             alignment: None,
         },
         Line {
             spans: [
                 Span {
                     content: ">",
                     style: Style {
                         fg: None,
                         bg: None,
                         underline_color: None,
                         add_modifier: NONE,
                         sub_modifier: NONE,
                     },
                 },
                 Span {
                     content: ">",
                     style: Style {
                         fg: None,
                         bg: None,
                         underline_color: None,
                         add_modifier: NONE,
                         sub_modifier: NONE,
                     },
                 },
                 Span {
                     content: " ",
                     style: Style {
                         fg: None,
                         bg: None,
                         underline_color: None,
                         add_modifier: NONE,
                         sub_modifier: NONE,
                     },
                 },
                 Span {
                     content: "Nested Blockquote",
                     style: Style {
                         fg: None,
                         bg: None,
                         underline_color: None,
                         add_modifier: NONE,
                         sub_modifier: NONE,
                     },
                 },
             ],
             style: Style {
                 fg: Some(
                     Green,
                 ),
                 bg: None,
                 underline_color: None,
                 add_modifier: NONE,
                 sub_modifier: NONE,
             },
             alignment: None,
         },
     ],
     style: Style {
         fg: None,
         bg: None,
         underline_color: None,
         add_modifier: NONE,
         sub_modifier: NONE,
     },
     alignment: None,
 }

Which becomes after modification:

 Text {
    style: Style {},
    alignment: None,
    lines: [
         Line {
            style: Style { fg: Green, },
            alignment: None,
            spans: [
                 Span {
                     content: ">",
                     style: Style {},
                 },
                 Span {
                     content: " ",
                     style: Style {},
                 },
                 Span {
                     content: "Blockquote 1",
                     style: Style {},
                 },
             ],
         },
         Line {
            style: Style { fg: Green },
            alignment: None,
            spans: [
                 Span {
                     content: ">",
                     style: Style {},
                 },
                 Span {
                     content: ">",
                     style: Style {},
                 },
                 Span {
                     content: " ",
                     style: Style {},
                 },
                 Span {
                     content: "Nested Blockquote",
                     style: Style {},
                 },
             ],
         },
     ],
 }

[joshka]

Omitting default values entirely, and collapsing spans that don't have non-default values to just a string:

 Text {
    lines: [
         Line {
            style: Style { fg: Green, },
            spans: [
                 Span { ">" },
                 Span { " " },
                 Span { "Blockquote 1" },
             ],
         },
         Line {
            style: Style { fg: Green },
            spans: [
                 Span { ">" },
                 Span { ">" },
                 Span { " " },
                 Span { "Nested Blockquote" },
             ],
         },
     ],
 }

110 lines -> 21 lines