Run go generate during make and make sure that generated files ar…

…e in sync in CI (#101)

* Run go generate in the precommit target

So we should always get an updated version of a file generated by a
stringer utility.

* Update the generated file

* Make CI to fail if working tree has uncommited changes

The uncommitted changes may come from the golang linter (that formats
our code among other things) and from stringer (when updated some
enumeration).

Makefile

@@ -19,7 +19,11 @@ $(TOOLS_DIR)/golangci-lint: go.mod go.sum tools.go
 $(TOOLS_DIR)/misspell: go.mod go.sum tools.go
 	go build -o $(TOOLS_DIR)/misspell github.com/client9/misspell/cmd/misspell
 
-precommit: $(TOOLS_DIR)/golangci-lint  $(TOOLS_DIR)/misspell 
+$(TOOLS_DIR)/stringer: go.mod go.sum tools.go
+	go build -o $(TOOLS_DIR)/stringer golang.org/x/tools/cmd/stringer
+
+precommit: $(TOOLS_DIR)/golangci-lint  $(TOOLS_DIR)/misspell $(TOOLS_DIR)/stringer
+	PATH="$(abspath $(TOOLS_DIR)):$${PATH}" go generate ./...
 	$(TOOLS_DIR)/golangci-lint run --fix # TODO: Fix this on windows.
 	$(TOOLS_DIR)/misspell -w $(ALL_DOCS)
 
@@ -29,7 +33,17 @@ test-with-coverage:
 	go tool cover -html=coverage.txt -o coverage.html
 
 .PHONY: circle-ci
-circle-ci: precommit test-with-coverage test-386
+circle-ci: precommit test-clean-work-tree test-with-coverage test-386
+
+.PHONY: test-clean-work-tree
+test-clean-work-tree:
+	@if ! git diff --quiet; then \
+	  echo; \
+	  echo "Working tree is not clean"; \
+	  echo; \
+	  git status; \
+	  exit 1; \
+	fi
 
 .PHONY: test
 test:
@@ -43,4 +57,4 @@ all-pkgs:
 	@echo $(ALL_PKGS) | tr ' ' '\n' | sort
 
 all-docs:
-	@echo $(ALL_DOCS) | tr ' ' '\n' | sort
+	@echo $(ALL_DOCS) | tr ' ' '\n' | sort

tools.go

@@ -5,4 +5,5 @@ package tools
 import (
 	_ "github.com/client9/misspell/cmd/misspell"
 	_ "github.com/golangci/golangci-lint/cmd/golangci-lint"
+	_ "golang.org/x/tools/cmd/stringer"
 )