Modified snapshot tests to support tab expansion.

This changes how the files are named (to allow for snapshots that aren't
directly related to the --style argument) and fixes the
generate_snapshots.py script to work with the latest version of bat.

Three new tests are also introduced:
- tabs_4 - Tab expansion with a width of 4.
- tabs_8 - Tab expansion with a width of 8.
- tabs_passthrough - No tab expansion.

tests/tests.rs

@@ -3,33 +3,36 @@ mod tester;
 use tester::BatTester;
 
 macro_rules! snapshot_tests {
-    ($($test_name: ident: $style: expr,)*) => {
+    ($($test_name: ident: $style: expr => [tabs: $tabs:expr],)*) => {
         $(
             #[test]
             fn $test_name() {
                 let bat_tester = BatTester::new();
-                bat_tester.test_snapshot($style);
+                bat_tester.test_snapshot(stringify!($test_name), $style, $tabs);
             }
         )*
     };
 }
 
 snapshot_tests! {
-    changes: "changes",
-    grid: "grid",
-    header: "header",
-    numbers: "numbers",
-    changes_grid: "changes,grid",
-    changes_header: "changes,header",
-    changes_numbers: "changes,numbers",
-    grid_header: "grid,header",
-    grid_numbers: "grid,numbers",
-    header_numbers: "header,numbers",
-    changes_grid_header: "changes,grid,header",
-    changes_grid_numbers: "changes,grid,numbers",
-    changes_header_numbers: "changes,header,numbers",
-    grid_header_numbers: "grid,header,numbers",
-    changes_grid_header_numbers: "changes,grid,header,numbers",
-    full: "full",
-    plain: "plain",
+    changes: "changes" => [tabs: 8],
+    grid: "grid" => [tabs: 8],
+    header: "header" => [tabs: 8],
+    numbers: "numbers" => [tabs: 8],
+    changes_grid: "changes,grid" => [tabs: 8],
+    changes_header: "changes,header" => [tabs: 8],
+    changes_numbers: "changes,numbers" => [tabs: 8],
+    grid_header: "grid,header" => [tabs: 8],
+    grid_numbers: "grid,numbers" => [tabs: 8],
+    header_numbers: "header,numbers" => [tabs: 8],
+    changes_grid_header: "changes,grid,header" => [tabs: 8],
+    changes_grid_numbers: "changes,grid,numbers" => [tabs: 8],
+    changes_header_numbers: "changes,header,numbers" => [tabs: 8],
+    grid_header_numbers: "grid,header,numbers" => [tabs: 8],
+    changes_grid_header_numbers: "changes,grid,header,numbers" => [tabs: 8],
+    full: "full" => [tabs: 8],
+    plain: "plain" => [tabs: 8],
+    tabs_passthrough: "full" => [tabs: 0],
+    tabs_4: "full" => [tabs: 4],
+    tabs_8: "full" => [tabs: 8],
 }