[#133] Refactor golden tests

Problem: We're using a common pattern in our bats tests:
  Run xrefcheck, redirect output to a temp file
  Check the temp file matches some .gold file using `diff`
  Delete temp file
We could encapsulate this pattern and make it easier to reuse.

Solution: In the `setup` function, create a temp directory. In the
`teardown` function, delete the temp directory. Create a `to_temp`
function that runs xrefcheck with desired options, pipes its output
through the `prepare` helper function and saves it in a file inside
the temp directory. Create a `assert_diff` function that reads the temp
file, and uses `diff` to compare it against some expected output.

.gitmodules

@@ -8,3 +8,6 @@
 [submodule "tests/golden/helpers/bats-support"]
 	path = tests/golden/helpers/bats-support
 	url = git@github.com:bats-core/bats-support.git
+[submodule "tests/golden/helpers/bats-file"]
+	path = tests/golden/helpers/bats-file
+	url = https://github.com/bats-core/bats-file.git

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

@@ -6,16 +6,25 @@
 
 load '../helpers/bats-support/load'
 load '../helpers/bats-assert/load'
+load '../helpers/bats-file/load'
 load '../helpers'
 
 
 @test "Relative anchor, check error report" {
-  xrefcheck | prepare > /tmp/check-anchors.test || true
+  to_temp xrefcheck
 
-  diff /tmp/check-anchors.test expected.gold \
-    --ignore-space-change \
-    --ignore-blank-lines \
-    --new-file # treat absent files as empty
+  assert_diff - <<EOF
+=== Invalid references found ===
 
-  rm /tmp/check-anchors.test
+       ➥  In file check-relative-anchor.md
+          bad reference (relative) at src:7:1-40:
+            - text: "no-anchor"
+            - link: no-anchor.md
+            - anchor: invalid-anchor
+
+          ⛀  Anchor 'invalid-anchor' is not present
+
+
+Invalid references dumped, 1 in total.
+EOF
 }

tests/golden/check-anchors/expected.gold

@@ -1,12 +0,0 @@
-=== Invalid references found ===
-
-       ➥  In file check-relative-anchor.md
-          bad reference (relative) at src:7:1-40:
-            - text: "no-anchor"
-            - link: no-anchor.md
-            - anchor: invalid-anchor
-
-          ⛀  Anchor 'invalid-anchor' is not present
-
-
-Invalid references dumped, 1 in total.

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

@@ -6,6 +6,7 @@
 
 load '../helpers/bats-support/load'
 load '../helpers/bats-assert/load'
+load '../helpers/bats-file/load'
 load '../helpers'
 
 @test "No redundant slashes" {
@@ -41,41 +42,63 @@ load '../helpers'
 }
 
 @test "Basic root, check errors report" {
-  xrefcheck \
-    --root . \
-    | prepare > /tmp/check-cli.test || true
+  to_temp xrefcheck --root .
 
-  diff /tmp/check-cli.test expected.gold \
-    --ignore-space-change \
-    --ignore-blank-lines \
-    --new-file # treat absent files as empty
+  assert_diff - <<EOF
+=== Invalid references found ===
 
-  rm /tmp/check-cli.test
+  ➥  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
 }
 
 @test "Root with redundant slashes, check errors report" {
-  xrefcheck \
-    --root ././///././././//./ \
-    | prepare > /tmp/check-cli.test || true
+  to_temp xrefcheck --root ././///././././//./
 
-  diff /tmp/check-cli.test expected.gold \
-    --ignore-space-change \
-    --ignore-blank-lines \
-    --new-file # treat absent files as empty
+  assert_diff - <<EOF
+=== Invalid references found ===
 
-  rm /tmp/check-cli.test
+  ➥  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
 }
 
 @test "No root, check errors report" {
-  xrefcheck \
-    | prepare > /tmp/check-cli.test || true
+  to_temp xrefcheck
 
-  diff /tmp/check-cli.test expected.gold \
-    --ignore-space-change \
-    --ignore-blank-lines \
-    --new-file # treat absent files as empty
+  assert_diff - <<EOF
+=== Invalid references found ===
 
-  rm /tmp/check-cli.test
+  ➥  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
 }
 
 @test "Single file as root" {

tests/golden/check-cli/expected.gold

@@ -1,13 +0,0 @@
-=== 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-html/check.html.bats

@@ -6,6 +6,7 @@
 
 load '../helpers/bats-support/load'
 load '../helpers/bats-assert/load'
+load '../helpers/bats-file/load'
 load '../helpers'
 
 

tests/golden/check-ignoreRefs/check-ignoreRefs.bats

@@ -6,6 +6,7 @@
 
 load '../helpers/bats-support/load'
 load '../helpers/bats-assert/load'
+load '../helpers/bats-file/load'
 load '../helpers'
 
 @test "Ignore localhost" {
@@ -17,17 +18,11 @@ load '../helpers'
 }
 
 @test "Ignore localhost, check errors" {
-  xrefcheck \
+  to_temp xrefcheck \
     -c config-check-enabled.yaml \
-    -r . \
-    | prepare > /tmp/check-localhost.test || true
+    -r .
 
-  diff /tmp/check-localhost.test expected.gold \
-    --ignore-space-change \
-    --ignore-blank-lines \
-    --new-file # treat absent files as empty
-
-  rm /tmp/check-localhost.test
+  assert_diff expected.gold
 }
 
 @test "Ignore localhost, no config specified" {

tests/golden/check-ignored/check-ignored.bats

@@ -6,6 +6,7 @@
 
 load '../helpers/bats-support/load'
 load '../helpers/bats-assert/load'
+load '../helpers/bats-file/load'
 load '../helpers'
 
 
@@ -33,14 +34,8 @@ load '../helpers'
   assert_output --partial "All repository links are valid."
 }
 
-@test "Ignore file with broken xrefcheck annotation: directory, check filure" {
-  xrefcheck --ignored ./to-ignore/inner-directory/ \
-  | prepare > /tmp/check-ignored.test || true
+@test "Ignore file with broken xrefcheck annotation: directory, check failure" {
+  to_temp xrefcheck --ignored ./to-ignore/inner-directory/
 
-  diff /tmp/check-ignored.test expected.gold \
-    --ignore-space-change \
-    --ignore-blank-lines \
-    --new-file # treat absent files as empty
-
-  rm /tmp/check-ignored.test
+  assert_diff expected.gold
 }

tests/golden/check-notScanned/check-notScanned.bats

@@ -6,6 +6,7 @@
 
 load '../helpers/bats-support/load'
 load '../helpers/bats-assert/load'
+load '../helpers/bats-file/load'
 load '../helpers'
 
 
@@ -28,13 +29,21 @@ load '../helpers'
 }
 
 @test "Not scanned: directory, check failure" {
-  xrefcheck -c config-directory.yaml \
-  | prepare > /tmp/check-notScanned.test || true
+  to_temp xrefcheck -c config-directory.yaml
 
-  diff /tmp/check-notScanned.test expected.gold \
-    --ignore-space-change \
-    --ignore-blank-lines \
-    --new-file # treat absent files as empty
+  assert_diff - <<EOF
+=== Invalid references found ===
 
-  rm /tmp/check-notScanned.test
+  ➥  In file notScanned/inner-directory/bad-reference.md
+     bad reference (absolute) at src:7:1-28:
+       - text: "Bad reference"
+       - link: /no-file.md
+       - anchor: -
+
+     ⛀  File does not exist:
+        ./no-file.md
+
+
+Invalid references dumped, 1 in total.
+EOF
 }

tests/golden/check-notScanned/expected.gold

@@ -1,13 +0,0 @@
-=== Invalid references found ===
-
-  ➥  In file notScanned/inner-directory/bad-reference.md
-     bad reference (absolute) at src:7:1-28:
-       - text: "Bad reference"
-       - link: /no-file.md
-       - anchor: -
-
-     ⛀  File does not exist:
-        ./no-file.md
-
-
-Invalid references dumped, 1 in total.

tests/golden/check-scan-errors/check-scan-errors.bats

@@ -6,16 +6,12 @@
 
 load '../helpers/bats-support/load'
 load '../helpers/bats-assert/load'
+load '../helpers/bats-file/load'
 load '../helpers'
 
 
 @test "Dump all errors along with broken links" {
-  xrefcheck | prepare > /tmp/check-scan-errors.test || true
+  to_temp xrefcheck
 
-  diff /tmp/check-scan-errors.test expected.gold \
-    --ignore-space-change \
-    --ignore-blank-lines \
-    --new-file # treat absent files as empty
-
-  rm /tmp/check-scan-errors.test
+  assert_diff expected.gold
 }

tests/golden/check-virtualFiles/check-virtualFiles.bats

@@ -6,6 +6,7 @@
 
 load '../helpers/bats-support/load'
 load '../helpers/bats-assert/load'
+load '../helpers/bats-file/load'
 load '../helpers'
 
 
@@ -16,12 +17,7 @@ load '../helpers'
 }
 
 @test "Virtual files: check failure" {
-  xrefcheck | prepare > /tmp/check-virtualFiles.test || true
+  to_temp xrefcheck
 
-  diff /tmp/check-virtualFiles.test expected.gold \
-    --ignore-space-change \
-    --ignore-blank-lines \
-    --new-file # treat absent files as empty
-
-  rm /tmp/check-virtualFiles.test
+  assert_diff expected.gold
 }

tests/golden/helpers.bash

@@ -5,6 +5,11 @@
 setup () {
   # change working directory to the location of the running `bats` suite.
   cd "$( dirname "$BATS_TEST_FILENAME")"
+  TEST_TEMP_DIR="$(temp_make)"
+}
+
+teardown() {
+  temp_del "$TEST_TEMP_DIR"
 }
 
 # this function is used for:
@@ -17,3 +22,54 @@ prepare () {
     | sed 's/socket: [0-9]*/socket: N/g' \
     | sed 's/Network.Socket.connect: <socket: N>: does not exist (Connection refused),//g'
 }
+
+# Create temporary file with program output, used with `assert_diff`.
+to_temp() {
+  output_file="$TEST_TEMP_DIR/temp_file.test"
+  $@ | prepare > $output_file
+}
+
+# Uses `diff` to compare output file created by `to_temp` against expected output.
+# Expected output could be given either:
+# - in the form of a filepath, e.g. `assert_diff expected.gold`
+# - via stdin when `-` is used, e.g. `assert_diff -`
+# Usage examples:
+# - filepath:
+#
+# @test "Ignore localhost, check errors" {
+#   to_temp xrefcheck \
+#     -c config-check-enabled.yaml \
+#     -r .
+#
+#   assert_diff expected.gold
+# }
+#
+# - stdin:
+# @test "Relative anchor, check error report" {
+#   to_temp xrefcheck
+#
+#   assert_diff - <<EOF
+# === Invalid references found ===
+#
+#        ➥  In file check-relative-anchor.md
+#           bad reference (relative) at src:7:1-40:
+#             - text: "no-anchor"
+#             - link: no-anchor.md
+#             - anchor: invalid-anchor
+#
+#           ⛀  Anchor 'invalid-anchor' is not present
+#
+#
+# Invalid references dumped, 1 in total.
+# EOF
+# }
+assert_diff() {
+  : "{output_file?}"
+
+  diff $output_file $1 \
+    --ignore-space-change \
+    --ignore-tab-expansion \
+    --ignore-trailing-space \
+    --ignore-blank-lines \
+    --new-file # treat absent files as empty
+}

tests/golden/helpers/bats-file

@@ -0,0 +1 @@
+Subproject commit f9154f43104322f9a30fb0a9e63c7cc46c5a8dc2