[
  {
    "name": "under the cap: everything is charged",
    "args": [
      [
        {
          "date": "2026-03-02",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 500,
            "currency": "GBP"
          }
        },
        {
          "date": "2026-03-09",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 500,
            "currency": "GBP"
          }
        }
      ],
      {
        "minor": 2000,
        "currency": "GBP"
      },
      1
    ],
    "expect": {
      "charges": [
        {
          "date": "2026-03-02",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 500,
            "currency": "GBP"
          },
          "charged": {
            "minor": 500,
            "currency": "GBP"
          },
          "waived": {
            "minor": 0,
            "currency": "GBP"
          }
        },
        {
          "date": "2026-03-09",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 500,
            "currency": "GBP"
          },
          "charged": {
            "minor": 500,
            "currency": "GBP"
          },
          "waived": {
            "minor": 0,
            "currency": "GBP"
          }
        }
      ],
      "totalCharged": {
        "minor": 1000,
        "currency": "GBP"
      },
      "totalWaived": {
        "minor": 0,
        "currency": "GBP"
      }
    }
  },
  {
    "name": "exactly at the cap: nothing is waived",
    "args": [
      [
        {
          "date": "2026-03-02",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 1000,
            "currency": "GBP"
          }
        },
        {
          "date": "2026-03-09",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 1000,
            "currency": "GBP"
          }
        }
      ],
      {
        "minor": 2000,
        "currency": "GBP"
      },
      1
    ],
    "expect": {
      "charges": [
        {
          "date": "2026-03-02",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 1000,
            "currency": "GBP"
          },
          "charged": {
            "minor": 1000,
            "currency": "GBP"
          },
          "waived": {
            "minor": 0,
            "currency": "GBP"
          }
        },
        {
          "date": "2026-03-09",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 1000,
            "currency": "GBP"
          },
          "charged": {
            "minor": 1000,
            "currency": "GBP"
          },
          "waived": {
            "minor": 0,
            "currency": "GBP"
          }
        }
      ],
      "totalCharged": {
        "minor": 2000,
        "currency": "GBP"
      },
      "totalWaived": {
        "minor": 0,
        "currency": "GBP"
      }
    }
  },
  {
    "name": "the charge that crosses the cap is reduced, later ones waived",
    "args": [
      [
        {
          "date": "2026-03-02",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 800,
            "currency": "GBP"
          }
        },
        {
          "date": "2026-03-05",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 800,
            "currency": "GBP"
          }
        },
        {
          "date": "2026-03-06",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 800,
            "currency": "GBP"
          }
        },
        {
          "date": "2026-03-20",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 800,
            "currency": "GBP"
          }
        }
      ],
      {
        "minor": 2000,
        "currency": "GBP"
      },
      1
    ],
    "expect": {
      "charges": [
        {
          "date": "2026-03-02",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 800,
            "currency": "GBP"
          },
          "charged": {
            "minor": 800,
            "currency": "GBP"
          },
          "waived": {
            "minor": 0,
            "currency": "GBP"
          }
        },
        {
          "date": "2026-03-05",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 800,
            "currency": "GBP"
          },
          "charged": {
            "minor": 800,
            "currency": "GBP"
          },
          "waived": {
            "minor": 0,
            "currency": "GBP"
          }
        },
        {
          "date": "2026-03-06",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 800,
            "currency": "GBP"
          },
          "charged": {
            "minor": 400,
            "currency": "GBP"
          },
          "waived": {
            "minor": 400,
            "currency": "GBP"
          }
        },
        {
          "date": "2026-03-20",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 800,
            "currency": "GBP"
          },
          "charged": {
            "minor": 0,
            "currency": "GBP"
          },
          "waived": {
            "minor": 800,
            "currency": "GBP"
          }
        }
      ],
      "totalCharged": {
        "minor": 2000,
        "currency": "GBP"
      },
      "totalWaived": {
        "minor": 1200,
        "currency": "GBP"
      }
    }
  },
  {
    "name": "a new calendar month starts a fresh cap",
    "args": [
      [
        {
          "date": "2026-03-30",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 1500,
            "currency": "GBP"
          }
        },
        {
          "date": "2026-03-31",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 1500,
            "currency": "GBP"
          }
        },
        {
          "date": "2026-04-01",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 1500,
            "currency": "GBP"
          }
        }
      ],
      {
        "minor": 2000,
        "currency": "GBP"
      },
      1
    ],
    "expect": {
      "charges": [
        {
          "date": "2026-03-30",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 1500,
            "currency": "GBP"
          },
          "charged": {
            "minor": 1500,
            "currency": "GBP"
          },
          "waived": {
            "minor": 0,
            "currency": "GBP"
          }
        },
        {
          "date": "2026-03-31",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 1500,
            "currency": "GBP"
          },
          "charged": {
            "minor": 500,
            "currency": "GBP"
          },
          "waived": {
            "minor": 1000,
            "currency": "GBP"
          }
        },
        {
          "date": "2026-04-01",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 1500,
            "currency": "GBP"
          },
          "charged": {
            "minor": 1500,
            "currency": "GBP"
          },
          "waived": {
            "minor": 0,
            "currency": "GBP"
          }
        }
      ],
      "totalCharged": {
        "minor": 3500,
        "currency": "GBP"
      },
      "totalWaived": {
        "minor": 1000,
        "currency": "GBP"
      }
    }
  },
  {
    "name": "dates out of order are capped in date order but returned in input order",
    "args": [
      [
        {
          "date": "2026-03-20",
          "label": "Late fee",
          "amount": {
            "minor": 1500,
            "currency": "GBP"
          }
        },
        {
          "date": "2026-03-02",
          "label": "Early fee",
          "amount": {
            "minor": 1500,
            "currency": "GBP"
          }
        }
      ],
      {
        "minor": 2000,
        "currency": "GBP"
      },
      1
    ],
    "expect": {
      "charges": [
        {
          "date": "2026-03-20",
          "label": "Late fee",
          "amount": {
            "minor": 1500,
            "currency": "GBP"
          },
          "charged": {
            "minor": 500,
            "currency": "GBP"
          },
          "waived": {
            "minor": 1000,
            "currency": "GBP"
          }
        },
        {
          "date": "2026-03-02",
          "label": "Early fee",
          "amount": {
            "minor": 1500,
            "currency": "GBP"
          },
          "charged": {
            "minor": 1500,
            "currency": "GBP"
          },
          "waived": {
            "minor": 0,
            "currency": "GBP"
          }
        }
      ],
      "totalCharged": {
        "minor": 2000,
        "currency": "GBP"
      },
      "totalWaived": {
        "minor": 1000,
        "currency": "GBP"
      }
    }
  },
  {
    "name": "same-day charges keep their input order",
    "args": [
      [
        {
          "date": "2026-03-10",
          "label": "First",
          "amount": {
            "minor": 1500,
            "currency": "GBP"
          }
        },
        {
          "date": "2026-03-10",
          "label": "Second",
          "amount": {
            "minor": 1500,
            "currency": "GBP"
          }
        }
      ],
      {
        "minor": 2000,
        "currency": "GBP"
      },
      1
    ],
    "expect": {
      "charges": [
        {
          "date": "2026-03-10",
          "label": "First",
          "amount": {
            "minor": 1500,
            "currency": "GBP"
          },
          "charged": {
            "minor": 1500,
            "currency": "GBP"
          },
          "waived": {
            "minor": 0,
            "currency": "GBP"
          }
        },
        {
          "date": "2026-03-10",
          "label": "Second",
          "amount": {
            "minor": 1500,
            "currency": "GBP"
          },
          "charged": {
            "minor": 500,
            "currency": "GBP"
          },
          "waived": {
            "minor": 1000,
            "currency": "GBP"
          }
        }
      ],
      "totalCharged": {
        "minor": 2000,
        "currency": "GBP"
      },
      "totalWaived": {
        "minor": 1000,
        "currency": "GBP"
      }
    }
  },
  {
    "name": "cycle day 15: the 14th belongs to the previous period",
    "args": [
      [
        {
          "date": "2026-03-14",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 1500,
            "currency": "GBP"
          }
        },
        {
          "date": "2026-03-15",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 1500,
            "currency": "GBP"
          }
        },
        {
          "date": "2026-04-14",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 1500,
            "currency": "GBP"
          }
        }
      ],
      {
        "minor": 2000,
        "currency": "GBP"
      },
      15
    ],
    "expect": {
      "charges": [
        {
          "date": "2026-03-14",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 1500,
            "currency": "GBP"
          },
          "charged": {
            "minor": 1500,
            "currency": "GBP"
          },
          "waived": {
            "minor": 0,
            "currency": "GBP"
          }
        },
        {
          "date": "2026-03-15",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 1500,
            "currency": "GBP"
          },
          "charged": {
            "minor": 1500,
            "currency": "GBP"
          },
          "waived": {
            "minor": 0,
            "currency": "GBP"
          }
        },
        {
          "date": "2026-04-14",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 1500,
            "currency": "GBP"
          },
          "charged": {
            "minor": 500,
            "currency": "GBP"
          },
          "waived": {
            "minor": 1000,
            "currency": "GBP"
          }
        }
      ],
      "totalCharged": {
        "minor": 3500,
        "currency": "GBP"
      },
      "totalWaived": {
        "minor": 1000,
        "currency": "GBP"
      }
    }
  },
  {
    "name": "cycle day 15 across a year end",
    "args": [
      [
        {
          "date": "2025-12-20",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 1500,
            "currency": "GBP"
          }
        },
        {
          "date": "2026-01-10",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 1500,
            "currency": "GBP"
          }
        },
        {
          "date": "2026-01-15",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 1500,
            "currency": "GBP"
          }
        }
      ],
      {
        "minor": 2000,
        "currency": "GBP"
      },
      15
    ],
    "expect": {
      "charges": [
        {
          "date": "2025-12-20",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 1500,
            "currency": "GBP"
          },
          "charged": {
            "minor": 1500,
            "currency": "GBP"
          },
          "waived": {
            "minor": 0,
            "currency": "GBP"
          }
        },
        {
          "date": "2026-01-10",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 1500,
            "currency": "GBP"
          },
          "charged": {
            "minor": 500,
            "currency": "GBP"
          },
          "waived": {
            "minor": 1000,
            "currency": "GBP"
          }
        },
        {
          "date": "2026-01-15",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 1500,
            "currency": "GBP"
          },
          "charged": {
            "minor": 1500,
            "currency": "GBP"
          },
          "waived": {
            "minor": 0,
            "currency": "GBP"
          }
        }
      ],
      "totalCharged": {
        "minor": 3500,
        "currency": "GBP"
      },
      "totalWaived": {
        "minor": 1000,
        "currency": "GBP"
      }
    }
  },
  {
    "name": "a zero cap waives everything",
    "args": [
      [
        {
          "date": "2026-03-02",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 500,
            "currency": "GBP"
          }
        },
        {
          "date": "2026-03-09",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 700,
            "currency": "GBP"
          }
        }
      ],
      {
        "minor": 0,
        "currency": "GBP"
      },
      1
    ],
    "expect": {
      "charges": [
        {
          "date": "2026-03-02",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 500,
            "currency": "GBP"
          },
          "charged": {
            "minor": 0,
            "currency": "GBP"
          },
          "waived": {
            "minor": 500,
            "currency": "GBP"
          }
        },
        {
          "date": "2026-03-09",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 700,
            "currency": "GBP"
          },
          "charged": {
            "minor": 0,
            "currency": "GBP"
          },
          "waived": {
            "minor": 700,
            "currency": "GBP"
          }
        }
      ],
      "totalCharged": {
        "minor": 0,
        "currency": "GBP"
      },
      "totalWaived": {
        "minor": 1200,
        "currency": "GBP"
      }
    }
  },
  {
    "name": "zero charges are allowed and change nothing",
    "args": [
      [
        {
          "date": "2026-03-02",
          "label": "Waived fee",
          "amount": {
            "minor": 0,
            "currency": "GBP"
          }
        },
        {
          "date": "2026-03-03",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 2500,
            "currency": "GBP"
          }
        }
      ],
      {
        "minor": 2000,
        "currency": "GBP"
      },
      1
    ],
    "expect": {
      "charges": [
        {
          "date": "2026-03-02",
          "label": "Waived fee",
          "amount": {
            "minor": 0,
            "currency": "GBP"
          },
          "charged": {
            "minor": 0,
            "currency": "GBP"
          },
          "waived": {
            "minor": 0,
            "currency": "GBP"
          }
        },
        {
          "date": "2026-03-03",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 2500,
            "currency": "GBP"
          },
          "charged": {
            "minor": 2000,
            "currency": "GBP"
          },
          "waived": {
            "minor": 500,
            "currency": "GBP"
          }
        }
      ],
      "totalCharged": {
        "minor": 2000,
        "currency": "GBP"
      },
      "totalWaived": {
        "minor": 500,
        "currency": "GBP"
      }
    }
  },
  {
    "name": "no charges at all",
    "args": [
      [],
      {
        "minor": 2000,
        "currency": "GBP"
      },
      1
    ],
    "expect": {
      "charges": [],
      "totalCharged": {
        "minor": 0,
        "currency": "GBP"
      },
      "totalWaived": {
        "minor": 0,
        "currency": "GBP"
      }
    }
  },
  {
    "name": "a leap day is an ordinary date",
    "args": [
      [
        {
          "date": "2024-02-29",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 1200,
            "currency": "GBP"
          }
        },
        {
          "date": "2024-02-01",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 1200,
            "currency": "GBP"
          }
        }
      ],
      {
        "minor": 2000,
        "currency": "GBP"
      },
      1
    ],
    "expect": {
      "charges": [
        {
          "date": "2024-02-29",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 1200,
            "currency": "GBP"
          },
          "charged": {
            "minor": 800,
            "currency": "GBP"
          },
          "waived": {
            "minor": 400,
            "currency": "GBP"
          }
        },
        {
          "date": "2024-02-01",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 1200,
            "currency": "GBP"
          },
          "charged": {
            "minor": 1200,
            "currency": "GBP"
          },
          "waived": {
            "minor": 0,
            "currency": "GBP"
          }
        }
      ],
      "totalCharged": {
        "minor": 2000,
        "currency": "GBP"
      },
      "totalWaived": {
        "minor": 400,
        "currency": "GBP"
      }
    }
  },
  {
    "name": "a negative charge is an error",
    "args": [
      [
        {
          "date": "2026-03-02",
          "label": "Refund",
          "amount": {
            "minor": -500,
            "currency": "GBP"
          }
        }
      ],
      {
        "minor": 2000,
        "currency": "GBP"
      },
      1
    ],
    "expectError": "must not be negative"
  },
  {
    "name": "a charge in another currency is an error",
    "args": [
      [
        {
          "date": "2026-03-02",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 500,
            "currency": "EUR"
          }
        }
      ],
      {
        "minor": 2000,
        "currency": "GBP"
      },
      1
    ],
    "expectError": "currency mismatch: EUR and GBP"
  },
  {
    "name": "cycle day 29 is refused",
    "args": [
      [],
      {
        "minor": 2000,
        "currency": "GBP"
      },
      29
    ],
    "expectError": "cycleDay must be 1 to 28"
  },
  {
    "name": "cycle day 0 is refused",
    "args": [
      [],
      {
        "minor": 2000,
        "currency": "GBP"
      },
      0
    ],
    "expectError": "cycleDay must be 1 to 28"
  },
  {
    "name": "a negative cap is an error",
    "args": [
      [],
      {
        "minor": -1,
        "currency": "GBP"
      },
      1
    ],
    "expectError": "monthlyCap must not be negative"
  },
  {
    "name": "an impossible date is an error",
    "args": [
      [
        {
          "date": "2026-02-30",
          "label": "Unarranged overdraft fee",
          "amount": {
            "minor": 500,
            "currency": "GBP"
          }
        }
      ],
      {
        "minor": 2000,
        "currency": "GBP"
      },
      1
    ],
    "expectError": "not a real calendar date"
  }
]