Called manually this works:
# neo4j-shell -file /tmp/fixture.txt

Called from a state the -file /tmp/fixture.txt part is ignored.

# tests.sls
test-setup-fixture:
  cmd.run:
    - name: neo4j-shell -file /tmp/fixture.txt

# salt-call state.sls project.tests saltenv=vendor

          ID: test-setup-fixture
    Function: cmd.run
        Name: neo4j-shell -file /tmp/fixture.txt
      Result: False
     Comment: Command "neo4j-shell -file /tmp/fixture.txt" run
     Started: 13:17:42.928671
    Duration: 589.294 ms
     Changes:
              ----------
              pid:
                  2892
              retcode:
                  1
              stderr:
                  ERROR (-v for expanded information):
                  	Connection refused
              stdout:
                   -host      Domain name or IP of host to connect to (default: localhost)
                   -port      Port of host to connect to (default: 1337)
                   -name      RMI name, i.e. rmi://<host>:<port>/<name> (default: shell)
                   -pid       Process ID to connect to
                   -c         Command line to execute. After executing it the shell exits
                   -file      File containing commands to execute, or '-' to read from stdin. After executing it the shell exits
                   -readonly  Connect in readonly mode (only for connecting with -path)
                   -path      Points to a neo4j db path so that a local server can be started there
                   -config    Points to a config file when starting a local server

                  Example arguments for remote:
                  	-port 1337
                  	-host 192.168.1.234 -port 1337 -name shell
                  	-host localhost -readonly
                  	...or no arguments for default values
                  Example arguments for local:
                  	-path /path/to/db
                  	-path /path/to/db -config /path/to/neo4j.config
                  	-path /path/to/db -readonly