[Chore] Tests: golden files, add BATS_ACCEPT

Problem: in golden tests, it was impossible to automatically accept
changes en masse, e.g. if formatting changed.

Solution: factor out golden files (i.e. don't inline the expected output
directly in *.bats) and introduce a BATS_ACCEPT=1 option to update the
expected output.

The main change is in `assert_diff`, and the rest of the patch updates
its use sites accordingly.

tests/golden/check-anchors/check-anchors.bats

@@ -10,72 +10,13 @@ load '../helpers/bats-file/load'
 load '../helpers'
 
 @test "We report ambiguous anchor references" {
+  golden_file=$(realpath expected1.gold)
   to_temp xrefcheck -r ambiguous-anchors
-assert_diff - <<EOF
-=== Invalid references found ===
-
-  ➥  In file a.md
-     bad reference (file-local) at src:16:1-43:
-       - text: "ambiguous anchor in this file"
-       - anchor: some-text
-
-     Ambiguous reference to anchor 'some-text'
-       In file a.md
-       It could refer to either:
-         - some-text (header I) at src:6:1-11
-         - some-text (header I) at src:8:1-15
-         - some-text (header II) at src:12:1-12
-       Use of ambiguous anchors is discouraged because the target
-       can change silently while the document containing it evolves.
-
-  ➥  In file b.md
-     bad reference (relative) at src:7:1-48:
-       - text: "ambiguous anchor in other file"
-       - link: a.md
-       - anchor: some-text
-
-     Ambiguous reference to anchor 'some-text'
-       In file a.md
-       It could refer to either:
-         - some-text (header I) at src:6:1-11
-         - some-text (header I) at src:8:1-15
-         - some-text (header II) at src:12:1-12
-       Use of ambiguous anchors is discouraged because the target
-       can change silently while the document containing it evolves.
-
-Invalid references dumped, 2 in total.
-EOF
+  assert_diff
 }
 
 @test "We report references to non-existing anchors, giving hints about similar ones" {
+  golden_file=$(realpath expected2.gold)
   to_temp xrefcheck -r non-existing-anchors
-assert_diff - <<EOF
-=== Invalid references found ===
-
-  ➥  In file a.md
-     bad reference (file-local) at src:12:1-13:
-       - text: "broken"
-       - anchor: h3
-
-     Anchor 'h3' is not present, did you mean:
-         - h1 (header I) at src:6:1-4
-         - h2 (header II) at src:8:1-5
-
-  ➥  In file a.md
-     bad reference (file-local) at src:14:1-18:
-       - text: "broken"
-       - anchor: heading
-
-     Anchor 'heading' is not present, did you mean:
-         - the-heading (header I) at src:10:1-13
-
-  ➥  In file a.md
-     bad reference (file-local) at src:16:1-31:
-       - text: "broken"
-       - anchor: really-unique-anchor
-
-     Anchor 'really-unique-anchor' is not present
-
-Invalid references dumped, 3 in total.
-EOF
+  assert_diff
 }

tests/golden/check-anchors/expected1.gold

@@ -0,0 +1,32 @@
+=== Invalid references found ===
+
+  ➥  In file a.md
+     bad reference (file-local) at src:16:1-43:
+       - text: "ambiguous anchor in this file"
+       - anchor: some-text
+
+     Ambiguous reference to anchor 'some-text'
+       In file a.md
+       It could refer to either:
+         - some-text (header I) at src:6:1-11
+         - some-text (header I) at src:8:1-15
+         - some-text (header II) at src:12:1-12
+       Use of ambiguous anchors is discouraged because the target
+       can change silently while the document containing it evolves.
+
+  ➥  In file b.md
+     bad reference (relative) at src:7:1-48:
+       - text: "ambiguous anchor in other file"
+       - link: a.md
+       - anchor: some-text
+
+     Ambiguous reference to anchor 'some-text'
+       In file a.md
+       It could refer to either:
+         - some-text (header I) at src:6:1-11
+         - some-text (header I) at src:8:1-15
+         - some-text (header II) at src:12:1-12
+       Use of ambiguous anchors is discouraged because the target
+       can change silently while the document containing it evolves.
+
+Invalid references dumped, 2 in total.

tests/golden/check-anchors/expected2.gold

@@ -0,0 +1,27 @@
+=== Invalid references found ===
+
+  ➥  In file a.md
+     bad reference (file-local) at src:12:1-13:
+       - text: "broken"
+       - anchor: h3
+
+     Anchor 'h3' is not present, did you mean:
+         - h1 (header I) at src:6:1-4
+         - h2 (header II) at src:8:1-5
+
+  ➥  In file a.md
+     bad reference (file-local) at src:14:1-18:
+       - text: "broken"
+       - anchor: heading
+
+     Anchor 'heading' is not present, did you mean:
+         - the-heading (header I) at src:10:1-13
+
+  ➥  In file a.md
+     bad reference (file-local) at src:16:1-31:
+       - text: "broken"
+       - anchor: really-unique-anchor
+
+     Anchor 'really-unique-anchor' is not present
+
+Invalid references dumped, 3 in total.

tests/golden/check-autolinks/check-autolinks.bats

@@ -10,33 +10,7 @@ load '../helpers/bats-file/load'
 load '../helpers'
 
 @test "We're finding and checking autolinks" {
+  golden_file=$(realpath expected.gold)
   to_temp xrefcheck -v
-assert_diff - <<EOF
-=== Repository data ===
-
-  file-with-autolinks.md:
-    - references:
-        - reference (external):
-            - text: "https://www.google.com/doodles"
-            - link: https://www.google.com/doodles
-        - reference (external) at src:8:0-18:
-            - text: "www.commonmark.org"
-            - link: http://www.commonmark.org
-    - anchors:
-        none
-
-=== Invalid references found ===
-
-  ➥  In file file-with-autolinks.md
-     bad reference (external) at src:8:0-18:
-       - text: "www.commonmark.org"
-       - link: http://www.commonmark.org
-
-     Permanent redirect found:
-       -| http://www.commonmark.org
-       -> https://commonmark.org
-          ^-- stopped before this one
-
-Invalid references dumped, 1 in total.
-EOF
+  assert_diff
 }

tests/golden/check-autolinks/expected.gold

@@ -0,0 +1,26 @@
+=== Repository data ===
+
+  file-with-autolinks.md:
+    - references:
+        - reference (external):
+            - text: "https://www.google.com/doodles"
+            - link: https://www.google.com/doodles
+        - reference (external) at src:8:0-18:
+            - text: "www.commonmark.org"
+            - link: http://www.commonmark.org
+    - anchors:
+        none
+
+=== Invalid references found ===
+
+  ➥  In file file-with-autolinks.md
+     bad reference (external) at src:8:0-18:
+       - text: "www.commonmark.org"
+       - link: http://www.commonmark.org
+
+     Permanent redirect found:
+       -| http://www.commonmark.org
+       -> https://commonmark.org
+          ^-- stopped before this one
+
+Invalid references dumped, 1 in total.

tests/golden/check-backslash/check-backslash.bats

@@ -11,8 +11,9 @@ load '../helpers'
 
 
 @test "Checking files with backslash" {
+  golden_file=$(realpath expected.gold)
+
   cp a.md $TEST_TEMP_DIR
-  cp expected.gold $TEST_TEMP_DIR
   touch "$TEST_TEMP_DIR/a\a.md" || \
     return 0 # Cannot be tested on Windows
 
@@ -29,5 +30,5 @@ EOF
 
   to_temp xrefcheck -v
 
-  assert_diff expected.gold
+  assert_diff
 }

tests/golden/check-case-sensitivity-anchor/check-case-sensitivity-anchor.bats

@@ -11,13 +11,13 @@ load '../helpers'
 
 
 @test "GitHub anchors: check, ambiguous and similar detection is case-insensitive" {
+  golden_file=$(realpath expected1.gold)
   to_temp xrefcheck -c config-github.yaml
-
-  assert_diff expected1.gold
+  assert_diff
 }
 
 @test "GitLab anchors: check and ambiguous detection is case-sensitive, but similar detection is not"  {
+  golden_file=$(realpath expected2.gold)
   to_temp xrefcheck -c config-gitlab.yaml
-
-  assert_diff expected2.gold
+  assert_diff
 }

tests/golden/check-case-sensitivity-path/check-case-sensitivity-path.bats

@@ -11,13 +11,13 @@ load '../helpers'
 
 
 @test "GitHub paths: case-sensitive" {
+  golden_file=$(realpath expected.gold)
   to_temp xrefcheck -v -c config-github.yaml
-
-  assert_diff expected.gold
+  assert_diff
 }
 
 @test "GitLab paths: case-sensitive"  {
+  golden_file=$(realpath expected.gold)
   to_temp xrefcheck -v -c config-gitlab.yaml
-
-  assert_diff expected.gold
+  assert_diff
 }

tests/golden/check-cli/check-cli.bats

@@ -42,60 +42,21 @@ load '../helpers'
 }
 
 @test "Basic root, check errors report" {
+  golden_file=$(realpath expected1.gold)
   to_temp xrefcheck --root .
-
-  assert_diff - <<EOF
-=== Invalid references found ===
-
-  ➥  In file to-ignore/broken-link.md
-     bad reference (absolute) at src:7:1-25:
-       - text: "my link"
-       - link: /one/two/three
-       - anchor: -
-
-     File does not exist:
-       one/two/three
-
-Invalid references dumped, 1 in total.
-EOF
+  assert_diff
 }
 
 @test "Root with redundant slashes, check errors report" {
+  golden_file=$(realpath expected2.gold)
   to_temp xrefcheck --root ././///././././//./
-
-  assert_diff - <<EOF
-=== Invalid references found ===
-
-  ➥  In file to-ignore/broken-link.md
-     bad reference (absolute) at src:7:1-25:
-       - text: "my link"
-       - link: /one/two/three
-       - anchor: -
-
-     File does not exist:
-       one/two/three
-
-Invalid references dumped, 1 in total.
-EOF
+  assert_diff
 }
 
 @test "No root, check errors report" {
+  golden_file=$(realpath expected3.gold)
   to_temp xrefcheck
-
-  assert_diff - <<EOF
-=== Invalid references found ===
-
-  ➥  In file to-ignore/broken-link.md
-     bad reference (absolute) at src:7:1-25:
-       - text: "my link"
-       - link: /one/two/three
-       - anchor: -
-
-     File does not exist:
-       one/two/three
-
-Invalid references dumped, 1 in total.
-EOF
+  assert_diff
 }
 
 @test "Single file as root" {

tests/golden/check-cli/expected1.gold

@@ -0,0 +1,12 @@
+=== Invalid references found ===
+
+  ➥  In file to-ignore/broken-link.md
+     bad reference (absolute) at src:7:1-25:
+       - text: "my link"
+       - link: /one/two/three
+       - anchor: -
+
+     File does not exist:
+       one/two/three
+
+Invalid references dumped, 1 in total.

tests/golden/check-cli/expected2.gold

@@ -0,0 +1,12 @@
+=== Invalid references found ===
+
+  ➥  In file to-ignore/broken-link.md
+     bad reference (absolute) at src:7:1-25:
+       - text: "my link"
+       - link: /one/two/three
+       - anchor: -
+
+     File does not exist:
+       one/two/three
+
+Invalid references dumped, 1 in total.

tests/golden/check-cli/expected3.gold

@@ -0,0 +1,12 @@
+=== Invalid references found ===
+
+  ➥  In file to-ignore/broken-link.md
+     bad reference (absolute) at src:7:1-25:
+       - text: "my link"
+       - link: /one/two/three
+       - anchor: -
+
+     File does not exist:
+       one/two/three
+
+Invalid references dumped, 1 in total.