Merge #13281: test: Move linters to test/lint, add readme

fa3c910bfeab00703c947c5200a64c21225b50ef test: Move linters to test/lint, add readme (MarcoFalke)

Pull request description:

  This moves the checks and linters from `devtools` to a subfolder in `test`. (Motivated by my opinion that the dev tools are mostly for generating code and updating the repo whereas the linters are read-only checks.)

  Also, adds a readme to clarify that checks and linters are only meant to prevent bugs and user facing issues, not merely stylistic preference or inconsistencies. (This is motivated by the diversity in developers and work flows as well as existing code styles. It would be too disruptive to change all existing code to a single style or too burdensome to force all developers to adhere to a single style. Also note that our style guide is changing, so locking in at the wrong style "too early" would only waste resources.)

Tree-SHA512: 9b10e89f2aeaf0c8a9ae248aa891d74e0abf0569f8e5dfd266446efa8bfaf19f0ea0980abf0b0b22f0d8416ee90d7435d21a9f9285b66df43f370b7979173406

18 files changed, 42 insertions, 28 deletions

diff --git a/.travis.yml b/.travis.yml
index af5553f3b7..a798c46bd1 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -85,17 +85,17 @@ jobs:
             - python3-pip
             - shellcheck
       install:
-        - if [ "$TRAVIS_EVENT_TYPE" = "pull_request" ]; then travis_retry pip3 install flake8 --user; fi
+        - travis_retry pip3 install flake8 --user
       before_script:
         - git fetch --unshallow
-        - if [ "$TRAVIS_EVENT_TYPE" = "pull_request" ]; then contrib/devtools/commit-script-check.sh $TRAVIS_COMMIT_RANGE; fi
-        - contrib/devtools/git-subtree-check.sh src/crypto/ctaes
-        - contrib/devtools/git-subtree-check.sh src/secp256k1
-        - contrib/devtools/git-subtree-check.sh src/univalue
-        - contrib/devtools/git-subtree-check.sh src/leveldb
-        - contrib/devtools/check-doc.py
-        - contrib/devtools/check-rpc-mappings.py .
-        - if [ "$TRAVIS_EVENT_TYPE" = "pull_request" ]; then contrib/devtools/lint-all.sh; fi
+        - if [ "$TRAVIS_EVENT_TYPE" = "pull_request" ]; then test/lint/commit-script-check.sh $TRAVIS_COMMIT_RANGE; fi
+        - test/lint/git-subtree-check.sh src/crypto/ctaes
+        - test/lint/git-subtree-check.sh src/secp256k1
+        - test/lint/git-subtree-check.sh src/univalue
+        - test/lint/git-subtree-check.sh src/leveldb
+        - test/lint/check-doc.py
+        - test/lint/check-rpc-mappings.py .
+        - test/lint/lint-all.sh
       script:
         - if [ "$TRAVIS_REPO_SLUG" = "bitcoin/bitcoin" -a "$TRAVIS_PULL_REQUEST" = "false" ]; then while read LINE; do travis_retry gpg --keyserver hkp://subset.pool.sks-keyservers.net --recv-keys $LINE; done < contrib/verify-commits/trusted-keys; fi
         - if [ "$TRAVIS_REPO_SLUG" = "bitcoin/bitcoin" -a "$TRAVIS_EVENT_TYPE" = "cron" ]; then travis_wait 30 contrib/verify-commits/verify-commits.sh; fi
diff --git a/contrib/devtools/README.md b/contrib/devtools/README.md
index 7ac8aa39d3..690b8c7dc6 100644
--- a/contrib/devtools/README.md
+++ b/contrib/devtools/README.md
@@ -93,23 +93,6 @@ example:
 BUILDDIR=$PWD/build contrib/devtools/gen-manpages.sh
 ```
 
-git-subtree-check.sh
-====================
-
-Run this script from the root of the repository to verify that a subtree matches the contents of
-the commit it claims to have been updated to.
-
-To use, make sure that you have fetched the upstream repository branch in which the subtree is
-maintained:
-* for `src/secp256k1`: https://github.com/bitcoin-core/secp256k1.git (branch master)
-* for `src/leveldb`: https://github.com/bitcoin-core/leveldb.git (branch bitcoin-fork)
-* for `src/univalue`: https://github.com/bitcoin-core/univalue.git (branch master)
-* for `src/crypto/ctaes`: https://github.com/bitcoin-core/ctaes.git (branch master)
-
-Usage: `git-subtree-check.sh DIR (COMMIT)`
-
-`COMMIT` may be omitted, in which case `HEAD` is used.
-
 github-merge.py
 ===============
 
diff --git a/doc/developer-notes.md b/doc/developer-notes.md
index 1f237b750e..9081cab911 100644
--- a/doc/developer-notes.md
+++ b/doc/developer-notes.md
@@ -647,7 +647,7 @@ Others are external projects without a tight relationship with our project.  Cha
 be sent upstream but bugfixes may also be prudent to PR against Bitcoin Core so that they can be integrated
 quickly.  Cosmetic changes should be purely taken upstream.
 
-There is a tool in contrib/devtools/git-subtree-check.sh to check a subtree directory for consistency with
+There is a tool in `test/lint/git-subtree-check.sh` to check a subtree directory for consistency with
 its upstream repository.
 
 Current subtrees include:
@@ -778,7 +778,7 @@ To create a scripted-diff:
     - `-BEGIN VERIFY SCRIPT-`
     - `-END VERIFY SCRIPT-`
 
-The scripted-diff is verified by the tool `contrib/devtools/commit-script-check.sh`
+The scripted-diff is verified by the tool `test/lint/commit-script-check.sh`
 
 Commit [`bb81e173`](https://github.com/bitcoin/bitcoin/commit/bb81e173) is an example of a scripted-diff.
 
diff --git a/test/functional/README.md b/test/functional/README.md
index 21050cc2fa..fdd7c339c5 100644
--- a/test/functional/README.md
+++ b/test/functional/README.md
@@ -20,6 +20,8 @@ don't have test cases for.
 - Where possible, try to adhere to [PEP-8 guidelines](https://www.python.org/dev/peps/pep-0008/)
 - Use a python linter like flake8 before submitting PRs to catch common style
   nits (eg trailing whitespace, unused imports, etc)
+- See [the python lint script](/test/lint/lint-python.sh) that checks for violations that
+  could lead to bugs and issues in the test code.
 - Avoid wildcard imports where possible
 - Use a module-level docstring to describe what the test is testing, and how it
   is testing it.
diff --git a/test/lint/README.md b/test/lint/README.md
new file mode 100644
index 0000000000..15974a3598
--- /dev/null
+++ b/test/lint/README.md
@@ -0,0 +1,29 @@
+This folder contains lint scripts.
+
+check-doc.py
+============
+Check for missing documentation of command line options.
+
+commit-script-check.sh
+======================
+Verification of [scripted diffs](/doc/developer-notes.md#scripted-diffs).
+
+git-subtree-check.sh
+====================
+Run this script from the root of the repository to verify that a subtree matches the contents of
+the commit it claims to have been updated to.
+
+To use, make sure that you have fetched the upstream repository branch in which the subtree is
+maintained:
+* for `src/secp256k1`: https://github.com/bitcoin-core/secp256k1.git (branch master)
+* for `src/leveldb`: https://github.com/bitcoin-core/leveldb.git (branch bitcoin-fork)
+* for `src/univalue`: https://github.com/bitcoin-core/univalue.git (branch master)
+* for `src/crypto/ctaes`: https://github.com/bitcoin-core/ctaes.git (branch master)
+
+Usage: `git-subtree-check.sh DIR (COMMIT)`
+
+`COMMIT` may be omitted, in which case `HEAD` is used.
+
+lint-all.sh
+===========
+Calls other scripts with the `lint-` prefix.
diff --git a/contrib/devtools/check-doc.py b/test/lint/check-doc.py
index de5719eb29..de5719eb29 100755
--- a/contrib/devtools/check-doc.py
+++ b/test/lint/check-doc.py
diff --git a/contrib/devtools/check-rpc-mappings.py b/test/lint/check-rpc-mappings.py
index 7e96852c5c..7e96852c5c 100755
--- a/contrib/devtools/check-rpc-mappings.py
+++ b/test/lint/check-rpc-mappings.py
diff --git a/contrib/devtools/commit-script-check.sh b/test/lint/commit-script-check.sh
index 1c9dbc7f68..1c9dbc7f68 100755
--- a/contrib/devtools/commit-script-check.sh
+++ b/test/lint/commit-script-check.sh
diff --git a/contrib/devtools/git-subtree-check.sh b/test/lint/git-subtree-check.sh
index 184951715e..184951715e 100755
--- a/contrib/devtools/git-subtree-check.sh
+++ b/test/lint/git-subtree-check.sh
diff --git a/contrib/devtools/lint-all.sh b/test/lint/lint-all.sh
index b6d86959c6..b6d86959c6 100755
--- a/contrib/devtools/lint-all.sh
+++ b/test/lint/lint-all.sh
diff --git a/contrib/devtools/lint-include-guards.sh b/test/lint/lint-include-guards.sh
index 6a0dd556bb..6a0dd556bb 100755
--- a/contrib/devtools/lint-include-guards.sh
+++ b/test/lint/lint-include-guards.sh
diff --git a/contrib/devtools/lint-includes.sh b/test/lint/lint-includes.sh
index f54be46b52..f54be46b52 100755
--- a/contrib/devtools/lint-includes.sh
+++ b/test/lint/lint-includes.sh
diff --git a/contrib/devtools/lint-logs.sh b/test/lint/lint-logs.sh
index 35be13ec19..35be13ec19 100755
--- a/contrib/devtools/lint-logs.sh
+++ b/test/lint/lint-logs.sh
diff --git a/contrib/devtools/lint-python-shebang.sh b/test/lint/lint-python-shebang.sh
index f5c5971c03..f5c5971c03 100755
--- a/contrib/devtools/lint-python-shebang.sh
+++ b/test/lint/lint-python-shebang.sh
diff --git a/contrib/devtools/lint-python.sh b/test/lint/lint-python.sh
index 7d3555b6d4..7d3555b6d4 100755
--- a/contrib/devtools/lint-python.sh
+++ b/test/lint/lint-python.sh
diff --git a/contrib/devtools/lint-shell.sh b/test/lint/lint-shell.sh
index 5f5fa9a925..5f5fa9a925 100755
--- a/contrib/devtools/lint-shell.sh
+++ b/test/lint/lint-shell.sh
diff --git a/contrib/devtools/lint-tests.sh b/test/lint/lint-tests.sh
index ffc0660551..ffc0660551 100755
--- a/contrib/devtools/lint-tests.sh
+++ b/test/lint/lint-tests.sh
diff --git a/contrib/devtools/lint-whitespace.sh b/test/lint/lint-whitespace.sh
index c5d43043d5..c5d43043d5 100755
--- a/contrib/devtools/lint-whitespace.sh
+++ b/test/lint/lint-whitespace.sh