feat: use last predicted stop as added trip headsign

[Whoops]

Summary of changes

Asana Ticket: 🍎 Adjust API headsign logic for ADDED trips

[Please include a brief description of what was changed]

[github-actions]

Coverage of commit 3e27228

Summary coverage rate:
  lines......: 89.0% (4216 of 4736 lines)
  functions..: 70.2% (2285 of 3257 functions)
  branches...: no data found

Files changed coverage rate:
                                                                        |Lines       |Functions  |Branches    
  Filename                                                              |Rate     Num|Rate    Num|Rate     Num
  ============================================================================================================
  apps/state/lib/state/trip/added.ex                                    | 100%     32|72.7%    44|    -      0

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[Whoops]

Comparison from today's RL disruption with service suspended between Harvard and Broadway:
prod:

{
  "data": {
    "attributes": {
      "bikes_allowed": 0,
      "block_id": null,
      "direction_id": 0,
      "headsign": "Braintree",
      "name": "",
      "revenue": "REVENUE",
      "wheelchair_accessible": 1
    },
    "id": "ADDED-1582142747",
    "links": {
      "self": "/trips/ADDED-1582142747"
    },
    "relationships": {
      "route": {
        "data": {
          "id": "Red",
          "type": "route"
        }
      },
      "route_pattern": {
        "data": {
          "id": "Red-3-0",
          "type": "route_pattern"
        }
      },
      "service": {
        "data": null
      },
      "shape": {
        "data": {
          "id": "canonical-933_0009",
          "type": "shape"
        }
      }
    },
    "type": "trip"
  },
  "jsonapi": {
    "version": "1.0"
  }
}

dev-green:

{
  "data": {
    "attributes": {
      "bikes_allowed": 0,
      "block_id": null,
      "direction_id": 0,
      "headsign": "Harvard",
      "name": "",
      "revenue": "REVENUE",
      "wheelchair_accessible": 1
    },
    "id": "ADDED-1590682122",
    "links": {
      "self": "/trips/ADDED-1590682122"
    },
    "relationships": {
      "route": {
        "data": {
          "id": "Red",
          "type": "route"
        }
      },
      "route_pattern": {
        "data": {
          "id": "Red-3-0",
          "type": "route_pattern"
        }
      },
      "service": {
        "data": null
      },
      "shape": {
        "data": {
          "id": "canonical-933_0009",
          "type": "shape"
        }
      }
    },
    "type": "trip"
  },
  "jsonapi": {
    "version": "1.0"
  }
}

(Added trip IDs are not consistent between environments. I found these to compare by downloading the Prod/Green RT feeds and finding the predictions for vehicle R-547FBF60)

[bfauble]

would this make the headsign different for each prediction? it seems like it's applying it to every prediction along the trip rather than applying the last stop's prediction's stopname as the headsign

[Whoops]

Sorry, I should've called this out. Only the last prediction ever makes it to this function due to the reduce here. I can add the requested test to help demonstrate that.

[bfauble]

ah that makes sense, misread it as a simple sorting rather than just keeping the last 👍

[bfauble]

is it possible to add multiple predictions to verify that the headsign is being properly set for multiple predictions on the same trip?

[Whoops]

Test updated to use multiple predictions. There's also this test on for the route_pattern side that tests the same thing so this has us covering both the shape and route pattern sides of this functionality.

[github-actions]

Coverage of commit 358b6b2

Summary coverage rate:
  lines......: 89.0% (4216 of 4736 lines)
  functions..: 70.2% (2285 of 3257 functions)
  branches...: no data found

Files changed coverage rate:
                                                                        |Lines       |Functions  |Branches    
  Filename                                                              |Rate     Num|Rate    Num|Rate     Num
  ============================================================================================================
  apps/state/lib/state/trip/added.ex                                    | 100%     32|72.7%    44|    -      0

Download coverage report