add code coverage

Push coverage (lines %) to a gist, which then backs a
https://shields.io badge.

.github/workflows/coverage.yml

@@ -0,0 +1,26 @@
+name: Coverage
+
+on:
+  push:
+    branches: [ "main" ]
+
+jobs:
+  coverage:
+    runs-on: ubuntu-latest
+    environment: Code Coverage Badge
+    env:
+      CARGO_TERM_COLOR: always
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install cargo-llvm-cov
+        uses: taiki-e/install-action@cargo-llvm-cov
+      - name: Generate code coverage
+        run: |
+          percent_coverage="$(cargo llvm-cov --json | jq '.data[].totals.lines.percent')"
+          printf '::notice title=Coverage (lines %%)::%s' "$percent_coverage"
+          echo "LINES_PERCENT=$percent_coverage" >> "$GITHUB_ENV"
+      - name: Upload to gist
+        run: ./scripts/percent_to_shields_gist coverage "$LINES_PERCENT"
+        env:
+          GIST_URL: ${{ vars.GIST_URL }}
+          GH_TOKEN: ${{ secrets.API_TOKEN }}

.github/workflows/rust.yml

@@ -15,15 +15,15 @@ jobs:
     steps:
     - uses: actions/checkout@v4
     - name: cargo build
-      run:  .github/workflows/cargo_to_gh rustc --message-format json -- -Awarnings
+      run: scripts/cargo_to_gh rustc --message-format json -- -Awarnings
 
   check:
     runs-on: ubuntu-latest
     needs: build
     steps:
     - uses: actions/checkout@v4
     - name: cargo check
-      run: .github/workflows/cargo_to_gh check
+      run: scripts/cargo_to_gh check
 
   test:
     runs-on: ubuntu-latest

README.md

@@ -0,0 +1,2 @@
+![Code Coverage](https://img.shields.io/endpoint?url=https%3A%2F%2Fgist.githubusercontent.com%2Fyshavit%2F53901a0115b596e015a891c41fb0f256%2Fraw%2Fmdq-coverage.json)
+

.github/workflows/cargo_to_gh → scripts/cargo_to_gh

@@ -1,8 +1,9 @@
 #!/bin/bash
 
+source scripts/common.sh || exit 1
+
 json_opts=()
 if ! echo "$*" | grep -q -- '--message-format json' ; then
-  echo "NO: $*"
   json_opts=(--message-format json)
 fi
 

scripts/common.sh

@@ -0,0 +1,10 @@
+set -euo pipefail
+
+function msg() {
+  echo >&2 "$@"
+}
+
+function err() {
+  msg "$@"
+  exit 1
+}

scripts/percent_to_color

@@ -0,0 +1,31 @@
+#!/bin/bash
+
+source scripts/common.sh || exit 1
+
+if [ $# -ne 1 ]; then
+  err 'require exactly one argument'
+fi
+percent="$1"
+
+percent_0_to_5="$(printf 'scale=0; %s / 20\n' "$percent" | bc)"
+
+case "$percent_0_to_5" in
+  0) # 0 - 19%
+    echo darkred
+    ;;
+  1) # 20 - 39%
+    echo crimson
+    ;;
+  2) # 40 - 59%
+    echo orangered
+    ;;
+  3) # 60 - 79%
+    echo yellowgreen
+    ;;
+  4 | 5)
+    echo forestgreen 
+    ;;
+  *)
+    err 'invalid percent'
+    ;;
+esac

scripts/percent_to_shields_gist

@@ -0,0 +1,22 @@
+#!/bin/bash
+
+source scripts/common.sh || exit 1
+
+if [ -z "${GIST_URL:-}" ]; then
+  err "no GIST_URL env set"
+fi
+if [ $# -ne 2 ]; then
+  err 'requires exactly two arguments'
+fi
+label="$1"
+percent="$2"
+
+color="$(scripts/percent_to_color "$percent")"
+
+json_text="$(echo '{}' | 
+  jq -c '{schemaVersion: 1, label: $badge_label, color: $color, message: $percent}' \
+  --arg badge_label "$label" --arg color "$color" --arg percent "$(printf '%.1f%%' "$percent")" )"
+
+gh gist edit "$GIST_URL" <(echo "$json_text")
+
+