cli: add --track-dir option

With this commit, we can now establish a beginning state by specifying:
- a track directory
- a problem-specifications directory
- the offline mode

This allows us to do black-box testing of the release binary, running
something like:
    configlet -t /tmp/python -p /tmp/my_prob_specs --offline
and then asserting that the changes made are as expected.

Closes: exercism#50

README.md

@@ -26,6 +26,7 @@ Options for uuid:
 Global options:
   -h, --help                   Show this help message and exit
       --version                Show this tool's version information and exit
+  -t, --track-dir <dir>        Specify a track directory to use instead of the current directory
   -v, --verbosity <verbosity>  The verbosity of output. Allowed values: q[uiet], n[ormal], d[etailed]
 ```
 

src/cli.nim

@@ -35,11 +35,13 @@ type
 
   Conf* = object
     action*: Action
+    trackDir*: string
     verbosity*: Verbosity
 
   Opt = enum
     optHelp = "help"
     optVersion = "version"
+    optTrackDir = "trackDir"
     optVerbosity = "verbosity"
     optSyncExercise = "exercise"
     optSyncCheck = "check"
@@ -110,6 +112,7 @@ func genHelpText: string =
     for opt in Opt:
       let paramName =
         case opt
+        of optTrackDir: "dir"
         of optVerbosity: "verbosity"
         of optSyncExercise: "slug"
         of optSyncMode: "mode"
@@ -127,6 +130,7 @@ func genHelpText: string =
   const descriptions: array[Opt, string] = [
     optHelp: "Show this help message and exit",
     optVersion: "Show this tool's version information and exit",
+    optTrackDir: "Specify a track directory to use instead of the current directory",
     optVerbosity: &"The verbosity of output. {allowedValues(Verbosity)}",
     optSyncExercise: "Only sync this exercise",
     optSyncCheck: "Terminates with a non-zero exit code if one or more tests " &
@@ -310,6 +314,8 @@ proc handleOption(conf: var Conf; kind: CmdLineKind; key, val: string) =
     showHelp()
   of optVersion:
     showVersion()
+  of optTrackDir:
+    setGlobalOpt(trackDir, val)
   of optVerbosity:
     setGlobalOpt(verbosity, parseVal[Verbosity](kind, key, val))
   else:

src/sync/tracks.nim

@@ -83,5 +83,9 @@ proc findTrackExercises(repo: TrackRepo, conf: Conf): seq[TrackExercise] =
       result.add(newTrackExercise(repoExercise))
 
 proc findTrackExercises*(conf: Conf): seq[TrackExercise] =
-  let trackRepo = newTrackRepo()
+  let trackRepo =
+    if conf.trackDir.len > 0:
+      TrackRepo(dir: conf.trackDir)
+    else:
+      newTrackRepo()
   trackRepo.findTrackExercises(conf)