test(cli): Verify terminal styling

This uses a new feature from snapbox that let's us render terminal
styling in SVG files.  This let's us see / visualize ANSI escape codes,
including in github's UI (will render images, including side-by-side
images for diffs).

Cargo.toml

@@ -91,7 +91,7 @@ sha1 = "0.10.6"
 sha2 = "0.10.8"
 shell-escape = "0.1.5"
 supports-hyperlinks = "2.1.0"
-snapbox = { version = "0.5.0", features = ["diff", "path"] }
+snapbox = { version = "0.5.3", features = ["diff", "path", "term-svg"] }
 tar = { version = "0.4.40", default-features = false }
 tempfile = "3.9.0"
 thiserror = "1.0.56"

crates/cargo-test-support/src/lib.rs

@@ -1319,6 +1319,7 @@ impl CargoCommand for snapbox::cmd::Command {
     fn cargo_ui() -> Self {
         Self::new(cargo_exe())
             .with_assert(compare::assert_ui())
+            .env("CARGO_TERM_COLOR", "always")
             .test_env()
     }
 }

tests/testsuite/cargo/help/mod.rs

@@ -8,6 +8,6 @@ fn case() {
         .arg("--help")
         .assert()
         .success()
-        .stdout_matches(file!["stdout.log"])
+        .stdout_matches(file!["stdout.term.svg"])
         .stderr_matches(str![""]);
 }

tests/testsuite/cargo/z_help/mod.rs

@@ -9,6 +9,6 @@ fn case() {
         .args(["-Z", "help"])
         .assert()
         .success()
-        .stdout_matches(file!["stdout.log"])
+        .stdout_matches(file!["stdout.term.svg"])
         .stderr_matches(str![""]);
 }