Limit tab completion of scan command to scans with installed components (#74)

* scans without installed requirements dont tab-complete

* added meets_requirements functions to classes

* updated tests

* added check for None case

pipeline/recon/amass.py

@@ -7,8 +7,9 @@ from luigi.util import inherits
 from luigi.contrib.sqla import SQLAlchemyTarget
 
 import pipeline.models.db_manager
-from .targets import TargetList
 from ..tools import tools
+from .targets import TargetList
+from .helpers import get_tool_state
 from ..models.target_model import Target
 
 
@@ -48,6 +49,15 @@ class AmassScan(luigi.Task):
         self.db_mgr = pipeline.models.db_manager.DBManager(db_location=self.db_location)
         self.results_subfolder = (Path(self.results_dir) / "amass-results").expanduser().resolve()
 
+    @staticmethod
+    def meets_requirements():
+        """ Reports whether or not this scan's needed tool(s) are installed or not """
+        needs = ["amass"]
+        tools = get_tool_state()
+
+        if tools:
+            return all([tools.get(x).get("installed") is True for x in needs])
+
     def requires(self):
         """ AmassScan depends on TargetList to run.