Merge #19172: test: Do not swallow flake8 exit code

5d77549 doc: Add mypy to test dependencies (Hennadii Stepanov)
7dda912 test: Do not swallow flake8 exit code (Hennadii Stepanov)

Pull request description:

  After #18210 the `flake8` exit code in `test/lint/lint-python.sh` just not used that makes the linter broken.

  This PR:
  - combines exit codes of `flake8` and `mypy` into the  `test/lint/lint-python.sh` exit code
  - documents `mypy` as the test dependency

ACKs for top commit:
  MarcoFalke:
    Approach ACK 5d77549, fine with me
  practicalswift:
    ACK 5d77549

Tree-SHA512: e948ba04dc4d73393967ebf3c6a26c40d428d33766382a0310fc64746cb7972e027bd62e7ea76898b742a656cf7d0fcda2fdd61560a21bfd7be249cea27f3d41

Author: fanquake

test/README.md

@@ -261,6 +261,7 @@ Use the `-v` option for verbose output.
 | Lint test | Dependency | Version [used by CI](../ci/lint/04_install.sh) | Installation
 |-----------|:----------:|:-------------------------------------------:|--------------
 | [`lint-python.sh`](lint/lint-python.sh) | [flake8](https://gitlab.com/pycqa/flake8) | [3.7.8](https://github.com/bitcoin/bitcoin/pull/15257) | `pip3 install flake8==3.7.8`
+| [`lint-python.sh`](lint/lint-python.sh) | [mypy](https://github.com/python/mypy) | [0.700](https://github.com/bitcoin/bitcoin/pull/18210) | `pip3 install mypy==0.700`
 | [`lint-shell.sh`](lint/lint-shell.sh) | [ShellCheck](https://github.com/koalaman/shellcheck) | [0.6.0](https://github.com/bitcoin/bitcoin/pull/15166) | [details...](https://github.com/koalaman/shellcheck#installing)
 | [`lint-shell.sh`](lint/lint-shell.sh) | [yq](https://github.com/kislyuk/yq) | default | `pip3 install yq`
 | [`lint-spelling.sh`](lint/lint-spelling.sh) | [codespell](https://github.com/codespell-project/codespell) | [1.15.0](https://github.com/bitcoin/bitcoin/pull/16186) | `pip3 install codespell==1.15.0`

test/lint/lint-python.sh

@@ -90,12 +90,20 @@ elif PYTHONWARNINGS="ignore" flake8 --version | grep -q "Python 2"; then
     exit 0
 fi
 
-PYTHONWARNINGS="ignore" flake8 --ignore=B,C,E,F,I,N,W --select=$(IFS=","; echo "${enabled[*]}") $(
+EXIT_CODE=0
+
+if ! PYTHONWARNINGS="ignore" flake8 --ignore=B,C,E,F,I,N,W --select=$(IFS=","; echo "${enabled[*]}") $(
     if [[ $# == 0 ]]; then
         git ls-files "*.py"
     else
         echo "$@"
     fi
-)
+); then
+    EXIT_CODE=1
+fi
+
+if ! mypy --ignore-missing-imports $(git ls-files "test/functional/*.py"); then
+    EXIT_CODE=1
+fi
 
-mypy --ignore-missing-imports $(git ls-files "test/functional/*.py")
+exit $EXIT_CODE