Add Makefile and add coverage check to CI

.github/workflows/go.yml

@@ -35,3 +35,12 @@ jobs:
       run: go build -v ./...
     - name: Test
       run: go test -v -race ./...
+    - name: Coverage
+      if: matrix.go == '1.27.x'
+      run: make cover-check
+    - name: Upload coverage profile
+      if: matrix.go == '1.27.x'
+      uses: actions/upload-artifact@v4
+      with:
+        name: coverage
+        path: cover.lib.out

.gitignore

@@ -6,4 +6,6 @@
 *.h264
 .idea/
 examples/playfromdisk/playfromdisk
-examples/savetodisk/savetodisk
+examples/savetodisk/savetodisk
+cover.out
+cover.lib.out

Makefile

@@ -0,0 +1,44 @@
+COVERPROFILE ?= cover.out
+COVERPROFILE_LIB ?= cover.lib.out
+COVER_THRESHOLD ?= 90
+
+.PHONY: all build test lint fmt vet coverprofile cover cover-html cover-check clean
+
+all: build test lint
+
+build:
+	go build ./...
+
+test:
+	go test -race ./...
+
+lint:
+	golangci-lint run
+
+fmt:
+	go fmt ./...
+
+vet:
+	go vet ./...
+
+# Run the full test suite with coverage. -coverpkg=./... is required so that the
+# integrationtests package is credited with the library code it exercises. The
+# examples are main packages with no tests so they are stripped from the profile
+# the reports are built from.
+coverprofile:
+	go test -covermode=atomic -coverpkg=./... -coverprofile=$(COVERPROFILE) ./...
+	grep -v '/examples/' $(COVERPROFILE) > $(COVERPROFILE_LIB)
+
+cover: coverprofile
+	@go tool cover -func=$(COVERPROFILE_LIB)
+
+cover-html: coverprofile
+	go tool cover -html=$(COVERPROFILE_LIB)
+
+cover-check: coverprofile
+	@total=$$(go tool cover -func=$(COVERPROFILE_LIB) | awk '/^total:/ {print $$NF}' | tr -d '%'); \
+	echo "total coverage: $$total% (threshold: $(COVER_THRESHOLD)%)"; \
+	awk -v t="$$total" -v min=$(COVER_THRESHOLD) 'BEGIN { if (t+0 < min+0) { printf "coverage %s%% is below threshold %s%%\n", t, min; exit 1 } }'
+
+clean:
+	rm -f $(COVERPROFILE) $(COVERPROFILE_LIB)