factor out LATEX_FLAGS

tests/Makefile

+# This Makefile intentionally rebuilds everytime everything.
+
 PDFLATEX		?= pdflatex
 XELATEX			?= xelatex
 LUALATEX		?= lualatex
+LATEX_FLAGS		?= -halt-on-error -interaction=nonstopmode
 
 export TEXINPUTS	:= $(CURDIR)/src//:$(TEXINPUTS)
 
-cmd%pdflatex		 = $(PDFLATEX)
-cmd%xelatex		 = $(XELATEX)
-cmd%lualatex		 = $(LUALATEX)
+cmd%pdflatex		 = $(PDFLATEX) $(LATEX_FLAGS)
+cmd%xelatex		 = $(XELATEX) $(LATEX_FLAGS)
+cmd%lualatex		 = $(LUALATEX) $(LATEX_FLAGS)
 
 engines			 = pdflatex xelatex lualatex
 targets			 = minimal minimal_handout tutorial many-pages
 
 %/minimal: src
 	@mkdir -p $(@D)
-	cd $(@D) && $(cmd%$*) -halt-on-error -interaction=nonstopmode ../../tutorial/minimal.tex
+	cd $(@D) && $(cmd%$*) ../../tutorial/minimal.tex
 
 %/minimal_handout: src
 	@mkdir -p $(@D)
-	cd $(@D) && $(cmd%$*) -halt-on-error -interaction=nonstopmode ../../tutorial/minimal_handout.tex
+	cd $(@D) && $(cmd%$*) ../../tutorial/minimal_handout.tex
 
 %/tutorial: src %/minimal %/minimal_handout
 	@mkdir -p $(@D)
-	cd $(@D) && $(cmd%$*) -halt-on-error -interaction=nonstopmode ../../tutorial/tutorial.tex
+	cd $(@D) && $(cmd%$*) ../../tutorial/tutorial.tex
 
 %/many-pages: src
 	@mkdir -p $(@D)
-	cd $(@D) && $(cmd%$*) -halt-on-error -interaction=nonstopmode ../many-pages.tex
+	cd $(@D) && $(cmd%$*) ../many-pages.tex
 
 all: $(engines)