Build: integrate translation system tests again

The Makefile test targets were lost when gettextize infrastructure was
introduced. Now it is re-added in its modernized form which counts with
generated .pot files.

ipatests/i18n.py is now explicitly setting character encoding in files
it generates. According to gettext manual chapter "Filling in the Header Entry"
the Content-Type header is language-specific so it does not make sense
to fill it in in .pot file.

https://fedorahosted.org/freeipa/ticket/6418

Reviewed-By: Martin Basti <mbasti@redhat.com>
Reviewed-By: Christian Heimes <cheimes@redhat.com>
Reviewed-By: Lukas Slebodnik <lslebodn@redhat.com>

Makefile.am

@@ -128,7 +128,7 @@ apilint:
 
 .PHONY: polint
 polint:
-	$(MAKE) -C $(srcdir)/po validate-src-strings
+	$(MAKE) -C $(srcdir)/po validate-src-strings validate-po test-gettext
 
 # Run pylint for all python files. Finds all python files/packages, skips
 # folders rpmbuild, freeipa-* and dist. Skip (match, but don't print) .*,

ipatests/i18n.py

@@ -546,7 +546,10 @@ def create_po(pot_file, po_file, mo_file):
     for k in po.metadata:
         if k.lower() == 'plural-forms':
             po.metadata[k] = 'nplurals=2; plural=(n != 1)'
-            break
+        # the auto-generated PO file should have charset set to UTF-8
+        # because we are using UTF-8 prefix and suffix below
+        elif k.lower() == 'content-type':
+            po.metadata[k] = 'Content-Type: text/plain; charset=UTF-8'
 
 
     # Iterate over all msgid's and form a msgstr by prepending

po/Makefile.hack.in

@@ -4,6 +4,7 @@
 
 DISTFILES.common.extra3 = Makefile.hack.in
 
+IPA_TEST_I18N = @top_srcdir@/ipatests/i18n.py
 MSGATTRIB = @MSGATTRIB@
 
 .PHONY: strip-po
@@ -20,3 +21,17 @@ strip-po:
 
 clean: mostlyclean
 	rm -f *~
+
+# linters
+test-gettext: $(DOMAIN).pot
+	$(IPA_TEST_I18N) --test-gettext
+
+validate-pot:
+	$(IPA_TEST_I18N) --show-strings --validate-pot $(DOMAIN).pot
+
+validate-po:
+	$(IPA_TEST_I18N) --show-strings --validate-po $(POFILES)
+
+# forcefully re-generate .pot file and test it
+validate-src-strings: $(DOMAIN).pot-update
+	$(MAKE) validate-pot