Implement hunk styles using style string arguments

- Do not apply foreground syntax style if it is "null syntect style"
  This isn't really correct. We should find either a valid sentinel
  value, or a way to only do the superimposing when we're doing
  syntax-highlighting.
- Add --zero-style option (style for unchanged hunk lines)
- Implement --color-only using an option rewrite rule

4 files changed, 13 insertions, 260 deletions

diff --git a/src/tests/ansi_test_utils.rs b/src/tests/ansi_test_utils.rs
index ccfbab6f..7e2ce6bd 100644
--- a/src/tests/ansi_test_utils.rs
+++ b/src/tests/ansi_test_utils.rs
@@ -1,86 +1,8 @@
 #[cfg(test)]
 pub mod ansi_test_utils {
-    use ansi_parser::{self, AnsiParser};
     use console::strip_ansi_codes;
-    use itertools::Itertools;
 
-    use crate::config::{ColorLayer::*, Config};
-    use crate::delta::State;
-    use crate::paint;
-
-    use ansi_parser::AnsiSequence::*;
-    use ansi_parser::Output::*;
-
-    // Note that ansi_parser seems to be parsing 24-bit sequences as TextBlock
-    // rather than Escape(SetGraphicsMode). As a workaround, we examime the
-    // TextBlock string value using functions such as
-    // string_has_some_background_color and string_has_some_foreground_color.
-
-    pub fn is_syntax_highlighted(line: &str) -> bool {
-        line.ansi_parse()
-            .filter(|tok| match tok {
-                TextBlock(s) => string_has_some_foreground_color(s),
-                Escape(SetGraphicsMode(parameters)) => parameters[0] == 38,
-                _ => false,
-            })
-            .next()
-            .is_some()
-    }
-
-    pub fn line_has_background_color(line: &str, state: &State, config: &Config) -> bool {
-        line.ansi_parse()
-            .filter(|tok| match tok {
-                TextBlock(s) => string_has_background_color(s, state, config),
-                _ => false,
-            })
-            .next()
-            .is_some()
-    }
-
-    pub fn line_has_no_background_color(line: &str) -> bool {
-        line.ansi_parse()
-            .filter(|tok| match tok {
-                TextBlock(s) => string_has_some_background_color(s),
-                _ => false,
-            })
-            .next()
-            .is_none()
-    }
-
-    fn string_has_background_color(string: &str, state: &State, config: &Config) -> bool {
-        let painted = config
-            .get_color(state, Background)
-            .unwrap_or_else(|| panic!("state {:?} does not have a background color", state))
-            .paint("");
-        let ansi_sequence = painted
-            .trim_end_matches(paint::ANSI_SGR_RESET)
-            .trim_end_matches("m");
-        string.starts_with(ansi_sequence)
-    }
-
-    fn string_has_some_background_color(s: &str) -> bool {
-        s.starts_with("\x1b[48;")
-    }
-
-    fn string_has_some_foreground_color(s: &str) -> bool {
-        s.starts_with("\x1b[38;")
-    }
-
-    pub fn assert_line_has_expected_ansi_sequences(line: &str, expected: &Vec<(&str, &str)>) {
-        let parsed_line = line.ansi_parse().filter(|token| match token {
-            Escape(SetGraphicsMode(parameters)) if parameters == &vec![0 as u32] => false,
-            _ => true,
-        });
-        for ((expected_ansi_sequence, _), ref token) in expected.iter().zip_eq(parsed_line) {
-            match token {
-                TextBlock(s) => {
-                    assert!(s.starts_with(*expected_ansi_sequence));
-                }
-                Escape(SetGraphicsMode(parameters)) => assert_eq!(parameters, &vec![0 as u32]),
-                _ => panic!("Unexpected token: {:?}", token),
-            }
-        }
-    }
+    use crate::config::Config;
 
     pub fn assert_has_color_other_than_plus_color(string: &str, config: &Config) {
         let (string_without_any_color, string_with_plus_color_only) =
diff --git a/src/tests/integration_test_utils.rs b/src/tests/integration_test_utils.rs
index cc4dc22b..1421ec56 100644
--- a/src/tests/integration_test_utils.rs
+++ b/src/tests/integration_test_utils.rs
@@ -8,22 +8,25 @@ pub mod integration_test_utils {
     use crate::config;
     use crate::delta::delta;
 
+    // TODO: These should be set in a more principled way, based on the default
+    // argument values.
     pub fn get_command_line_options() -> cli::Opt {
         cli::Opt {
             light: false,
             dark: false,
-            minus_style: None,
-            minus_emph_style: None,
-            plus_style: None,
-            plus_emph_style: None,
-            _deprecated_minus_color: None,
-            _deprecated_minus_emph_color: None,
-            _deprecated_plus_color: None,
-            _deprecated_plus_emph_color: None,
+            minus_style: "normal auto".to_string(),
+            minus_emph_style: "normal auto".to_string(),
+            zero_style: "syntax normal".to_string(),
+            plus_style: "syntax auto".to_string(),
+            plus_emph_style: "syntax auto".to_string(),
+            deprecated_minus_background_color: None,
+            deprecated_minus_emph_background_color: None,
+            deprecated_plus_background_color: None,
+            deprecated_plus_emph_background_color: None,
             color_only: false,
             keep_plus_minus_markers: false,
             theme: None,
-            highlight_minus_lines: false,
+            deprecated_highlight_minus_lines: false,
             commit_style: cli::SectionStyle::Plain,
             commit_color: "Yellow".to_string(),
             file_style: cli::SectionStyle::Underline,
diff --git a/src/tests/mod.rs b/src/tests/mod.rs
index afa09977..f95a9ef5 100644
--- a/src/tests/mod.rs
+++ b/src/tests/mod.rs
@@ -1,4 +1,3 @@
 pub mod ansi_test_utils;
 pub mod integration_test_utils;
 pub mod test_example_diffs;
-pub mod test_hunk_highlighting;
diff --git a/src/tests/test_hunk_highlighting.rs b/src/tests/test_hunk_highlighting.rs
deleted file mode 100644
index fdc5cfc5..00000000
--- a/src/tests/test_hunk_highlighting.rs
+++ /dev/null
@@ -1,171 +0,0 @@
-#[cfg(test)]
-mod tests {
-    use itertools::Itertools;
-
-    use ansi_term::Style;
-
-    use crate::cli;
-    use crate::config::ColorLayer::*;
-    use crate::delta::State;
-    use crate::paint;
-    use crate::tests::ansi_test_utils::ansi_test_utils;
-    use crate::tests::integration_test_utils::integration_test_utils;
-
-    const VERBOSE: bool = false;
-
-    #[test]
-    fn test_hunk_highlighting() {
-        let mut options = integration_test_utils::get_command_line_options();
-        options.theme = Some("GitHub".to_string());
-        options.max_line_distance = 1.0;
-        let minus_emph_background = "#ffa0a0";
-        let plus_emph_background = "#80ef80";
-        for minus_foreground in vec!["none", "green"] {
-            for minus_emph_foreground in vec!["none", "#80ef80"] {
-                for plus_foreground in vec!["none", "red"] {
-                    for plus_emph_foreground in vec!["none", "#ffa0a0"] {
-                        options.minus_style = Some(minus_foreground.to_string());
-                        options.minus_emph_style = Some(format!(
-                            "{} {}",
-                            minus_emph_foreground, minus_emph_background
-                        ));
-                        options.plus_style = Some(plus_foreground.to_string());
-                        options.plus_emph_style =
-                            Some(format!("{} {}", plus_emph_foreground, plus_emph_background));
-                        if VERBOSE {
-                            println!();
-                            print!(" --minus-style {:?}", options.minus_style);
-                            print!(" --minus-emph-style {:?}", options.minus_emph_style);
-                            print!(" --plus-style {:?}", options.plus_style);
-                            print!(" --plus-emph-style {:?}", options.plus_emph_style);
-                            println!();
-                        }
-                        _do_hunk_color_test(options.clone());
-                    }
-                }
-            }
-        }
-    }
-
-    fn _do_hunk_color_test(options: cli::Opt) {
-        let (output, config) = integration_test_utils::run_delta(
-            DIFF_YIELDING_ALL_HUNK_LINE_COLOR_CATEGORIES,
-            options,
-        );
-        let lines = output.trim().split("\n").skip(4);
-
-        let minus = Style::new()
-            .on(config.minus_style.background.unwrap())
-            .paint("")
-            .trim_end_matches(paint::ANSI_SGR_RESET)
-            .trim_end_matches("m")
-            .to_string();
-        let minus_emph = Style::new()
-            .on(config.minus_emph_style.background.unwrap())
-            .paint("")
-            .trim_end_matches(paint::ANSI_SGR_RESET)
-            .trim_end_matches("m")
-            .to_string();
-        let plus = Style::new()
-            .on(config.plus_style.background.unwrap())
-            .paint("")
-            .trim_end_matches(paint::ANSI_SGR_RESET)
-            .trim_end_matches("m")
-            .to_string();
-        let plus_emph = Style::new()
-            .on(config.plus_emph_style.background.unwrap())
-            .paint("")
-            .trim_end_matches(paint::ANSI_SGR_RESET)
-            .trim_end_matches("m")
-            .to_string();
-
-        let expectation = vec![
-            // line 1: unchanged
-            (
-                State::HunkZero,
-                vec![("", "(11111111, 11111111, 11111111)")],
-            ),
-            // line 2: removed, final token is minus-emph
-            (
-                State::HunkMinus,
-                vec![
-                    (minus.as_str(), "(22222222, 22222222"),
-                    (minus_emph.as_str(), ", 22222222"),
-                    (minus.as_str(), ")"),
-                ],
-            ),
-            // line 3: removed
-            (
-                State::HunkMinus,
-                vec![(minus.as_str(), "(33333333, 33333333, 33333333)")],
-            ),
-            // line 4: removed
-            (
-                State::HunkMinus,
-                vec![(minus.as_str(), "(44444444, 44444444, 44444444)")],
-            ),
-            // line 5: added, and syntax-higlighted.
-            (
-                State::HunkPlus,
-                vec![(plus.as_str(), "(22222222, 22222222)")],
-            ),
-            // line 6: added, and syntax-highlighted. First is plus-emph.
-            (
-                State::HunkPlus,
-                vec![
-                    (plus.as_str(), "("),
-                    (plus_emph.as_str(), "33333333, "),
-                    (plus.as_str(), "33333333, 33333333, 33333333)"),
-                ],
-            ),
-            // line 7: unchanged
-            (
-                State::HunkZero,
-                vec![("", "(55555555, 55555555, 55555555)")],
-            ),
-            // line 8: added, and syntax-highlighted.
-            (
-                State::HunkPlus,
-                vec![(plus.as_str(), "(66666666, 66666666, 66666666)")],
-            ),
-        ];
-
-        // TODO: check same length
-        for ((state, assertion), line) in expectation.iter().zip_eq(lines) {
-            if VERBOSE {
-                println!("{}", line)
-            };
-            if config.should_syntax_highlight(state) {
-                assert!(ansi_test_utils::is_syntax_highlighted(line));
-            } else {
-                // An explicit assertion about the ANSI sequences should be available (when there's
-                // syntax highlighting the pattern of ANSI sequences is too complex to make the
-                // assertion).
-                ansi_test_utils::assert_line_has_expected_ansi_sequences(line, &assertion)
-            }
-            // Background color should match the line's state.
-            match config.get_color(state, Background) {
-                Some(_color) => assert!(ansi_test_utils::line_has_background_color(
-                    line, state, &config
-                )),
-                None => assert!(ansi_test_utils::line_has_no_background_color(line)),
-            }
-        }
-    }
-
-    const DIFF_YIELDING_ALL_HUNK_LINE_COLOR_CATEGORIES: &str = r"
-diff --git a/file.py b/file.py
-index 15c0fa2..dc2254c 100644
---- a/file.py
-+++ b/file.py
-@@ -1,6 +1,6 @@
- (11111111, 11111111, 11111111)
--(22222222, 22222222, 22222222)
--(33333333, 33333333, 33333333)
--(44444444, 44444444, 44444444)
-+(22222222, 22222222)
-+(33333333, 33333333, 33333333, 33333333)
- (55555555, 55555555, 55555555)
-+(66666666, 66666666, 66666666)
-";
-}