Add a script to generate coverage locally (#8125)

# Description

This can be triggered manually and inspected for example with:

-
https://marketplace.visualstudio.com/items?itemName=ryanluker.vscode-coverage-gutters
- https://github.com/umaumax/vim-lcov
- https://github.com/andythigpen/nvim-coverage (probably with some
effort)

Currently I try to use the `--profile=ci` as well as the CI coverage
action relies on it but the flags passed to build and test differ.
First locally I don't run into the out of disk space problems of the CI
runners when also allowing the plugin tests to run. Furthermore I am not
fully sure what is going on with the recompilation between `cargo build`
and `cargo test`. Chose the most simple config, people might use for
running the test suite locally.



# User-Facing Changes

> Developers, Developers, Developers

Steve Ballmer

coverage-local.nu

@@ -0,0 +1,39 @@
+#!/usr/bin/env nu
+
+# Script to generate coverage locally
+#
+# Output: `lcov.info` file
+#
+# Relies on `cargo-llvm-cov`. Install via `cargo install cargo-llvm-cov`
+# https://github.com/taiki-e/cargo-llvm-cov
+
+# You probably have to run `cargo llvm-cov clean` once manually,
+# as you have to confirm to install additional tooling for your rustup toolchain.
+# Else the script might stall waiting for your `y<ENTER>`
+
+# Some of the internal tests rely on the exact cargo profile
+# (This is somewhat criminal itself)
+# but we have to signal to the tests that we use the `ci` `--profile`
+let-env NUSHELL_CARGO_TARGET = "ci"
+
+# Manual gathering of coverage to catch invocation of the `nu` binary.
+# This is relevant for tests using the `nu!` macro from `nu-test-support`
+# see: https://github.com/taiki-e/cargo-llvm-cov#get-coverage-of-external-tests
+
+# Enable LLVM coverage tracking through environment variables
+# show env outputs .ini/.toml style description of the variables
+cargo llvm-cov show-env | from toml | load-env
+cargo llvm-cov clean --workspace
+# Apparently we need to explicitly build the necessary parts
+# using the `--profile=ci` is basically `debug` build with unnecessary symbols stripped
+# leads to smaller binaries and potential savings when compiling and running
+cargo build --workspace --profile=ci
+cargo test --workspace --profile=ci
+# You need to provide the used profile to find the raw data
+cargo llvm-cov report --lcov --output-path lcov.info --profile=ci
+
+# To display the coverage in your editor see:
+#
+# - https://marketplace.visualstudio.com/items?itemName=ryanluker.vscode-coverage-gutters
+# - https://github.com/umaumax/vim-lcov
+# - https://github.com/andythigpen/nvim-coverage (probably needs some additional config)

coverage-local.sh

@@ -0,0 +1,38 @@
+#!/usr/bin/env bash
+
+# Script to generate coverage locally
+#
+# Output: `lcov.info` file
+#
+# Relies on `cargo-llvm-cov`. Install via `cargo install cargo-llvm-cov`
+# https://github.com/taiki-e/cargo-llvm-cov
+
+# You probably have to run `cargo llvm-cov clean` once manually,
+# as you have to confirm to install additional tooling for your rustup toolchain.
+# Else the script might stall waiting for your `y<ENTER>`
+
+# Some of the internal tests rely on the exact cargo profile
+# (This is somewhat criminal itself)
+# but we have to signal to the tests that we use the `ci` `--profile`
+export NUSHELL_CARGO_TARGET=ci
+
+# Manual gathering of coverage to catch invocation of the `nu` binary.
+# This is relevant for tests using the `nu!` macro from `nu-test-support`
+# see: https://github.com/taiki-e/cargo-llvm-cov#get-coverage-of-external-tests
+
+# Enable LLVM coverage tracking through environment variables
+source <(cargo llvm-cov show-env --export-prefix)
+cargo llvm-cov clean --workspace
+# Apparently we need to explicitly build the necessary parts
+# using the `--profile=ci` is basically `debug` build with unnecessary symbols stripped
+# leads to smaller binaries and potential savings when compiling and running
+cargo build --workspace --profile=ci
+cargo test --workspace --profile=ci
+# You need to provide the used profile to find the raw data
+cargo llvm-cov report --lcov --output-path lcov.info --profile=ci
+
+# To display the coverage in your editor see:
+#
+# - https://marketplace.visualstudio.com/items?itemName=ryanluker.vscode-coverage-gutters
+# - https://github.com/umaumax/vim-lcov
+# - https://github.com/andythigpen/nvim-coverage (probably needs some additional config)