Split shell tests into files

I am mostly interested in running all python and vim tests separately from other 
tests.

tests/run_lint_tests.sh

@@ -0,0 +1,7 @@
+#!/bin/sh
+FAILED=0
+if ! ${PYTHON} scripts/powerline-lint -p powerline/config_files ; then
+	echo "Failed powerline-lint"
+	FAILED=1
+fi
+exit $FAILED

tests/run_python_tests.sh

@@ -0,0 +1,9 @@
+#!/bin/sh
+FAILED=0
+for file in tests/test_*.py ; do
+	if ! ${PYTHON} $file --verbose --catch ; then
+		echo "Failed test(s) from $file"
+		FAILED=1
+	fi
+done
+exit $FAILED

tests/run_shell_tests.sh

@@ -0,0 +1,9 @@
+#!/bin/sh
+FAILED=0
+if ! sh tests/test_shells/test.sh --fast ; then
+	echo "Failed shells"
+	if ${PYTHON} -c 'import platform, sys; sys.exit(1 * (platform.python_implementation() == "PyPy"))' ; then
+		FAILED=1
+	fi
+fi
+exit $FAILED

tests/run_vim_tests.sh

@@ -0,0 +1,11 @@
+#!/bin/sh
+FAILED=0
+for script in tests/*.vim ; do
+	if ! vim -u NONE -S $script || test -f message.fail ; then
+		echo "Failed script $script" >&2
+		cat message.fail >&2
+		rm message.fail
+		FAILED=1
+	fi
+done
+exit $FAILED

tests/test.sh

@@ -1,29 +1,11 @@
 #!/bin/sh
-: ${PYTHON:=python}
 FAILED=0
+export PYTHON="${PYTHON:=python}"
 export PYTHONPATH="${PYTHONPATH}:`realpath .`"
-for file in tests/test_*.py ; do
-	if ! ${PYTHON} $file --verbose --catch ; then
-		echo "Failed test(s) from $file"
+for script in tests/run_*_tests.sh ; do
+	if ! sh $script ; then
+		echo "Failed $script"
 		FAILED=1
 	fi
 done
-if ! ${PYTHON} scripts/powerline-lint -p powerline/config_files ; then
-	echo "Failed powerline-lint"
-	FAILED=1
-fi
-for script in tests/*.vim ; do
-	if ! vim -u NONE -S $script || test -f message.fail ; then
-		echo "Failed script $script" >&2
-		cat message.fail >&2
-		rm message.fail
-		FAILED=1
-	fi
-done
-if ! bash tests/test_shells/test.sh --fast ; then
-	echo "Failed shells"
-	if ${PYTHON} -c 'import platform, sys; sys.exit(1 * (platform.python_implementation() == "PyPy"))' ; then
-		FAILED=1
-	fi
-fi
 exit $FAILED