docs: Advise on virtual environment usage

Advise to use Tox rather than pipenv virtual environment.

CONTRIBUTING.md

@@ -1,6 +1,6 @@
 # Contribution Guide
 
-Mbed OS is an open source project and we really appreciate your contributions to the tools. We are committed to 
+Mbed OS is an open source project and we really appreciate your contributions to the tools. We are committed to
 fostering a welcoming community, please see our Code of Conduct, which can be found here:
 
 - [Code of Conduct](./CODE_OF_CONDUCT.md)
@@ -63,13 +63,13 @@ The `pre-commit` tool allows developers to easily install git hook scripts which
 must pass in our CI before a PR is merged. Using commit hooks ensures you can't commit code which violates our style
 and maintainability requirements.
 
-To install the commit hooks for the repository, run:
+To install the commit hooks for the repository (assuming you have activated your development environment as described in [the development guide](./DEVELOPMENT.md)), run:
+
 ```bash
-$ pipenv install --dev
-$ pipenv shell
 $ pre-commit install
 ```
-Our code checks and unit tests will now run automatically every time you try to `git commit` to the repository.
+Our code checks will now run automatically every time you try to `git commit` to the repository.
+
 If you prefer not to install the hook scripts, you can use
 ```bash
 $ pre-commit run

DEVELOPMENT.md

@@ -1,8 +1,8 @@
 # Development and Testing
 
-For development and testing purposes, it is essential to use a virtual environment. It is recommended that `pipenv >= 2018.11.26` is used.
+For development and testing purposes, it is essential to use a virtual environment.
 
-## Setup Python and Pipenv
+## Setup Python and tox
 
 `mbed-tools` is compatible with Python 3.6 or later.
 
@@ -16,16 +16,16 @@ Below are links to guides for correctly setting up a development ready version o
 
 On Windows we have also found the [Python Launcher for Windows](https://docs.python.org/3/using/windows.html) to be a reasonable alternative.
 
-After you have set up your Python 3 installation, install pipenv (the `--user` flag is important **never use `sudo` to install Python packages!**)
+After you have set up your Python 3 installation, install tox (the `--user` flag is important **never use `sudo` to install Python packages!**)
 
 ```bash
-pip install --user pipenv
+python(3) -m pip install --user tox
 ```
 
-Check that pipenv is in the binary path
+Check that tox is in the binary path
 
 ```bash
-pipenv --version
+tox --version
 ```
 
 If not, find the user base binary directory
@@ -49,25 +49,17 @@ Clone the `mbed-tools` GitHub repository
 git clone git@github.com:ARMmbed/mbed-tools.git
 ```
 
-Setup Pipenv to use Python 3 and install package development dependencies:
+Set up the development environment using tox (tox will create a development environment at mbed-tools/.venv):
 
 ```bash
 cd mbed-tools/
-pipenv --three
-pipenv install --dev --skip-lock
+tox -e dev
+source .venv/bin/activate
 ```
 
-You may omit the `--skip-lock` flag. Note creating the `Pipfile.lock` can take a long time!
-
 ## Unit Tests, Code Formatting and Static Analysis
 
-Shell into the virtual environment you have just created:
-
-```bash
-pipenv shell
-```
-
-Run `pre-commit` to run unit tests and static code analysis checks:
+After you have activated your development environment, run `pre-commit` to run unit tests and static code analysis checks:
 
 ```bash
 pre-commit run --all-files

README.md

@@ -39,7 +39,7 @@ The version scheme used follows [PEP440](https://www.python.org/dev/peps/pep-044
 
 - `<major>.<minor>.<patch>`
 
-Beta releases are used to give early access to new functionality, for testing and to get feedback on experimental 
+Beta releases are used to give early access to new functionality, for testing and to get feedback on experimental
 features. As such these releases may not be stable and should not be used for production. Additionally any interfaces
 introduced in a beta release may be removed or changed without notice. For **beta** releases the version will look as
 follows:
@@ -48,8 +48,7 @@ follows:
 
 ## Installation
 
-It is recommended that a virtual environment such as [Pipenv](https://github.com/pypa/pipenv/blob/master/README.md) is
-used for all installations to avoid Python dependency conflicts.
+We recommend installing `mbed-tools` in a Python virtual environment to avoid dependency conflicts.
 
 To install the most recent production quality release use:
 

docs/howto/mbed-tools-howto.md

@@ -8,7 +8,7 @@ You'll still need Mbed CLI for older versions of Mbed OS. You can install both t
 
 Mbed Tools is Python based, so you can install it with pip.
 
-**Tip:** We recommend using a virtual environment such as [Pipenv](https://github.com/pypa/pipenv/blob/master/README.md) to avoid Python dependency conflicts.
+**Tip:** We recommend using a virtual environment to avoid Python dependency conflicts.
 
 ## Prerequisite
 

news/202010091700.doc

@@ -0,0 +1 @@
+Advise on using Tox rather than pipenv virtual environment