Run cmake-init and setup flake.nix and default.nix

cmake/coverage.cmake

@@ -0,0 +1,33 @@
+# ---- Variables ----
+
+# We use variables separate from what CTest uses, because those have
+# customization issues
+set(
+    COVERAGE_TRACE_COMMAND
+    lcov -c -q
+    -o "${PROJECT_BINARY_DIR}/coverage.info"
+    -d "${PROJECT_BINARY_DIR}"
+    --include "${PROJECT_SOURCE_DIR}/*"
+    CACHE STRING
+    "; separated command to generate a trace for the 'coverage' target"
+)
+
+set(
+    COVERAGE_HTML_COMMAND
+    genhtml --legend -f -q
+    "${PROJECT_BINARY_DIR}/coverage.info"
+    -p "${PROJECT_SOURCE_DIR}"
+    -o "${PROJECT_BINARY_DIR}/coverage_html"
+    CACHE STRING
+    "; separated command to generate an HTML report for the 'coverage' target"
+)
+
+# ---- Coverage target ----
+
+add_custom_target(
+    coverage
+    COMMAND ${COVERAGE_TRACE_COMMAND}
+    COMMAND ${COVERAGE_HTML_COMMAND}
+    COMMENT "Generating coverage report"
+    VERBATIM
+)