Switch to unstable source-based code coverage

.github/workflows/main.yml

@@ -54,25 +54,6 @@ jobs:
         command: test
         args: --all-features --all-targets
 
-  coverage:
-    name: Code Coverage (+nightly)
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v2.3.4
-      - uses: actions-rs/toolchain@v1.0.7
-        with:
-          toolchain: nightly
-          override: true
-      - name: Run cargo-tarpaulin
-        uses: actions-rs/tarpaulin@v0.1
-        with:
-          version: '0.12.3'
-          timeout: 300
-      - name: Upload coverage report to Codecov
-        uses: codecov/codecov-action@v1.5.0
-        with:
-          token: ${{ secrets.CODECOV_TOKEN }}
-
   clippy:
     name: Clippy (+nightly)
     runs-on: ubuntu-latest
@@ -88,3 +69,49 @@ jobs:
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
           args: --all-features --all-targets -- -D warnings
+
+  coverage:
+    name: Coverage (+nightly)
+    # The large timeout is to accommodate nightly builds
+    timeout-minutes: 45
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2.3.4
+        with:
+          persist-credentials: false
+
+      - uses: actions-rs/toolchain@v1
+        with:
+          toolchain: nightly
+          override: true
+          profile: minimal
+          components: llvm-tools-preview
+
+      - name: Install rustfilt symbol demangler
+        run: |
+          cargo install rustfilt
+      - name: Rerun tests for coverage
+        env:
+          RUSTFLAGS: -Zinstrument-coverage -C link-dead-code -C debuginfo=2
+          LLVM_PROFILE_FILE: "${{ github.workspace }}/test.%p.profraw"
+          ZEBRA_SKIP_NETWORK_TESTS: 1
+          CARGO_INCREMENTAL: 0
+        run: |
+          cargo test
+          cargo test --no-run --message-format=json | jq -r "select(.profile.test == true) | .filenames[]" | grep -v dSYM - > filenames.txt
+      - name: Merge coverage data
+        run: |
+          $(rustc --print target-libdir)/../bin/llvm-profdata merge test.*.profraw -o test.profdata
+      - name: Generate detailed html coverage report for github artifact
+        run: |
+          $(rustc --print target-libdir)/../bin/llvm-cov show -format=html -ignore-filename-regex=".*/.cargo/registry/.*" -ignore-filename-regex=".*/.cargo/git/.*" -ignore-filename-regex=".*/.rustup/.*" -Xdemangler=rustfilt -show-instantiations -output-dir=./coverage -instr-profile=./test.profdata $(printf -- "-object %s " $(cat filenames.txt))
+      - uses: actions/upload-artifact@v2
+        with:
+          name: coverage
+          path: ./coverage
+
+      - name: Generate lcov coverage report for codecov
+        run: |
+          $(rustc --print target-libdir)/../bin/llvm-cov export -format=lcov -instr-profile=test.profdata $(printf -- "-object %s " $(cat filenames.txt)) > "lcov.info"
+      - name: Upload coverage report to Codecov
+        uses: codecov/codecov-action@v1.5.2