Clean up and consolidate .gitignores

* Global ignores at toplevel .gitignore
* Component-specific ignores in each toplevel directory
* Remove `actionview/test/tmp/.keep` for JRuby

```
rm actionview/test/tmp/ -fr
cd actionview/
bundle exec jruby -Itest test/template/digestor_test.rb
```

Related to #11743, #30392.

Closes #29978.

14 files changed, 32 insertions, 36 deletions

diff --git a/.gitignore b/.gitignore
index da3b42cfbb..ab9ca8a6ac 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,25 +1,16 @@
-# Don't put *.swp, *.bak, etc here; those belong in a global ~/.gitignore.
+# Don't put *.swp, *.bak, etc here; those belong in a global .gitignore.
 # Check out https://help.github.com/articles/ignoring-files for how to set that up.
 
 .Gemfile
-.ruby-version
 .byebug_history
-debug.log
-pkg
+.ruby-version
+/*/doc/
+/*/test/tmp/
 /.bundle
-/dist
-/doc/rdoc
-/*/doc
-/*/test/tmp
-/activerecord/sqlnet.log
-/activemodel/test/fixtures/fixture_database.sqlite3
-/activesupport/test/fixtures/isolation_test
-/activestorage/test/service/configurations.yml
-/railties/test/500.html
-/railties/test/fixtures/tmp
-/railties/test/initializer/root/log
-/railties/doc
-/railties/tmp
-/guides/output
+/dist/
+/doc/
+/guides/output/
+debug.log
 node_modules/
-/actionview/log
+package-lock.json
+pkg/
diff --git a/actioncable/.gitignore b/actioncable/.gitignore
index 0a04b29786..f514e58c16 100644
--- a/actioncable/.gitignore
+++ b/actioncable/.gitignore
@@ -1,2 +1,2 @@
-/lib/assets/compiled
-/tmp
+/lib/assets/compiled/
+/tmp/
diff --git a/actionpack/test/tmp/.gitignore b/actionpack/test/tmp/.gitignore
deleted file mode 100644
index e69de29bb2..0000000000
--- a/actionpack/test/tmp/.gitignore
+++ /dev/null
diff --git a/actionview/.gitignore b/actionview/.gitignore
index 0a04b29786..246aabbb7f 100644
--- a/actionview/.gitignore
+++ b/actionview/.gitignore
@@ -1,2 +1,5 @@
-/lib/assets/compiled
-/tmp
+/lib/assets/compiled/
+/log/
+/test/fixtures/public/absolute/
+/test/ujs/log/
+/tmp/
diff --git a/actionview/test/fixtures/public/.gitignore b/actionview/test/fixtures/public/.gitignore
deleted file mode 100644
index 312e635ee6..0000000000
--- a/actionview/test/fixtures/public/.gitignore
+++ /dev/null
@@ -1 +0,0 @@
-absolute/*
diff --git a/actionview/test/tmp/.keep b/actionview/test/tmp/.keep
deleted file mode 100644
index e69de29bb2..0000000000
--- a/actionview/test/tmp/.keep
+++ /dev/null
diff --git a/actionview/test/ujs/.gitignore b/actionview/test/ujs/.gitignore
deleted file mode 100644
index 31dbbff57c..0000000000
--- a/actionview/test/ujs/.gitignore
+++ /dev/null
@@ -1 +0,0 @@
-/log
diff --git a/activerecord/.gitignore b/activerecord/.gitignore
new file mode 100644
index 0000000000..884ee009eb
--- /dev/null
+++ b/activerecord/.gitignore
@@ -0,0 +1,3 @@
+/sqlnet.log
+/test/config.yml
+/test/fixtures/*.sqlite*
diff --git a/activerecord/examples/.gitignore b/activerecord/examples/.gitignore
deleted file mode 100644
index 0dfc1cb7fb..0000000000
--- a/activerecord/examples/.gitignore
+++ /dev/null
@@ -1 +0,0 @@
-performance.sql
diff --git a/activerecord/test/.gitignore b/activerecord/test/.gitignore
deleted file mode 100644
index a0ec5967dd..0000000000
--- a/activerecord/test/.gitignore
+++ /dev/null
@@ -1 +0,0 @@
-/config.yml
diff --git a/activerecord/test/fixtures/.gitignore b/activerecord/test/fixtures/.gitignore
deleted file mode 100644
index 885029a512..0000000000
--- a/activerecord/test/fixtures/.gitignore
+++ /dev/null
@@ -1 +0,0 @@
-*.sqlite*
\ No newline at end of file
diff --git a/activestorage/.gitignore b/activestorage/.gitignore
index 29bdcc4468..3e78878ffc 100644
--- a/activestorage/.gitignore
+++ b/activestorage/.gitignore
@@ -1,7 +1,6 @@
-.byebug_history
-node_modules
-src
-test/dummy/db/*.sqlite3
-test/dummy/db/*.sqlite3-journal
-test/dummy/log/*.log
-test/dummy/tmp/
+/src/
+/test/dummy/db/*.sqlite3
+/test/dummy/db/*.sqlite3-journal
+/test/dummy/log/*.log
+/test/dummy/tmp/
+/test/service/configurations.yml
diff --git a/activesupport/.gitignore b/activesupport/.gitignore
new file mode 100644
index 0000000000..8cde8514fd
--- /dev/null
+++ b/activesupport/.gitignore
@@ -0,0 +1 @@
+/test/fixtures/isolation_test/
diff --git a/railties/.gitignore b/railties/.gitignore
index 80dd262d2f..c08562e016 100644
--- a/railties/.gitignore
+++ b/railties/.gitignore
@@ -1 +1,5 @@
-log/
+/log/
+/test/500.html
+/test/fixtures/tmp/
+/test/initializer/root/log/
+/tmp/