Track initialized and used columns in each processor

During 2026-03 invoicing, a bug was found where the columns initialized
by the New-PI credit processor (i.e `PI Balance` column), was
being accessed by the PI-SU processor before it was
initialized, causing an KeyError.

To fix this, the codebase has been refactored to allow each processor to
explicitly document which columns they initialize and use, defined in two
new properties, `initializes_columns` and `operates_on_columns`. A helper
function `_init_columns()` is added to initalize columns

Unit test `tests/unit/processors/test_processor_list.py` is added to check each processor
only uses columns that itself or previous processors initialized, and no
column is initialized more than once

Additionally, each column will now be encapsulated as a `InvoiceColumn` instance.
`InvoiceColumn` contains the name, datatype, and default values for each column
This will also enable stricter and clearer type enforcement for data entering
and leaving the pipeline

A new processor `ValidateInputColumnsProcessor` is added to check the input
dataframe to the processing pipeline has prerequisite columns, and to cast
to appropriate types

The e2e test data has been updated to surface the bug that was found.
It did not failed during the PR that introduced the bug [1] because
the test data didn't have the right conditions to trigger the PI-SU processor

Refactored unit tests to accomodate the new
processor by adding a new base test class.

[1] #279

Author: QuanMPhm

process_report/invoices/invoice.py

@@ -1,9 +1,28 @@
 from dataclasses import dataclass
+from typing import Any, Callable
+from decimal import Decimal
 import pandas
+import pyarrow
 
 import process_report.util as util
 
 
+@dataclass
+class InvoiceColumn:
+    name: str
+    dtype: Any
+    default_value: Any | None = None
+    default_initializer: Callable[[pandas.DataFrame], pandas.Series] | None = None
+
+
+# Field type definitions
+BALANCE_FIELD_TYPE = pandas.ArrowDtype(pyarrow.decimal128(21, 2))
+RATE_FIELD_TYPE = pandas.ArrowDtype(pyarrow.decimal128(21, 13))
+INTEGER_FIELD_TYPE = pandas.ArrowDtype(pyarrow.int64())
+STRING_FIELD_TYPE = pandas.StringDtype()
+BOOL_FIELD_TYPE = pandas.BooleanDtype()
+
+
 ### PI file field names
 PI_PI_FIELD = "PI"
 PI_FIRST_MONTH = "First Invoice Month"
@@ -65,18 +84,77 @@
 IS_COURSE_FIELD = "Is Course"
 ###
 
+### Initialized Column objects
+INVOICE_DATE_COLUMN = InvoiceColumn(name=INVOICE_DATE_FIELD, dtype=STRING_FIELD_TYPE)
+PROJECT_COLUMN = InvoiceColumn(name=PROJECT_FIELD, dtype=STRING_FIELD_TYPE)
+PROJECT_ID_COLUMN = InvoiceColumn(name=PROJECT_ID_FIELD, dtype=STRING_FIELD_TYPE)
+PI_COLUMN = InvoiceColumn(name=PI_FIELD, dtype=STRING_FIELD_TYPE)
+INVOICE_EMAIL_COLUMN = InvoiceColumn(name=INVOICE_EMAIL_FIELD, dtype=STRING_FIELD_TYPE)
+INVOICE_ADDRESS_COLUMN = InvoiceColumn(
+    name=INVOICE_ADDRESS_FIELD, dtype=STRING_FIELD_TYPE
+)
+INSTITUTION_COLUMN = InvoiceColumn(name=INSTITUTION_FIELD, dtype=STRING_FIELD_TYPE)
+INSTITUTION_ID_COLUMN = InvoiceColumn(
+    name=INSTITUTION_ID_FIELD, dtype=STRING_FIELD_TYPE
+)
+GROUP_NAME_COLUMN = InvoiceColumn(name=GROUP_NAME_FIELD, dtype=STRING_FIELD_TYPE)
+GROUP_INSTITUTION_COLUMN = InvoiceColumn(
+    name=GROUP_INSTITUTION_FIELD, dtype=STRING_FIELD_TYPE
+)
+GROUP_BALANCE_COLUMN = InvoiceColumn(name=GROUP_BALANCE_FIELD, dtype=BALANCE_FIELD_TYPE)
+GROUP_BALANCE_USED_COLUMN = InvoiceColumn(
+    name=GROUP_BALANCE_USED_FIELD, dtype=BALANCE_FIELD_TYPE
+)
+SU_HOURS_COLUMN = InvoiceColumn(name=SU_HOURS_FIELD, dtype=INTEGER_FIELD_TYPE)
+SU_TYPE_COLUMN = InvoiceColumn(name=SU_TYPE_FIELD, dtype=STRING_FIELD_TYPE)
+SU_CHARGE_COLUMN = InvoiceColumn(name=SU_CHARGE_FIELD, dtype=BALANCE_FIELD_TYPE)
+LENOVO_CHARGE_COLUMN = InvoiceColumn(name=LENOVO_CHARGE_FIELD, dtype=BALANCE_FIELD_TYPE)
+RATE_COLUMN = InvoiceColumn(
+    name=RATE_FIELD, dtype=RATE_FIELD_TYPE
+)  # Using decimal to suppress scientific notation in export
+COST_COLUMN = InvoiceColumn(name=COST_FIELD, dtype=BALANCE_FIELD_TYPE)
+CREDIT_COLUMN = InvoiceColumn(name=CREDIT_FIELD, dtype=BALANCE_FIELD_TYPE)
+CREDIT_CODE_COLUMN = InvoiceColumn(name=CREDIT_CODE_FIELD, dtype=STRING_FIELD_TYPE)
+SUBSIDY_COLUMN = InvoiceColumn(
+    name=SUBSIDY_FIELD, dtype=BALANCE_FIELD_TYPE, default_value=Decimal(0)
+)
+BALANCE_COLUMN = InvoiceColumn(
+    name=BALANCE_FIELD,
+    dtype=BALANCE_FIELD_TYPE,
+    default_initializer=lambda df: df[COST_FIELD],
+)
+PI_BALANCE_COLUMN = InvoiceColumn(
+    name=PI_BALANCE_FIELD,
+    dtype=BALANCE_FIELD_TYPE,
+    default_initializer=lambda df: df[COST_FIELD],
+)
+
+# Internally used fields
+IS_BILLABLE_COLUMN = InvoiceColumn(name=IS_BILLABLE_FIELD, dtype=BOOL_FIELD_TYPE)
+MISSING_PI_COLUMN = InvoiceColumn(name=MISSING_PI_FIELD, dtype=BOOL_FIELD_TYPE)
+PROJECT_NAME_COLUMN = InvoiceColumn(name=PROJECT_NAME_FIELD, dtype=STRING_FIELD_TYPE)
+GROUP_MANAGED_COLUMN = InvoiceColumn(name=GROUP_MANAGED_FIELD, dtype=BOOL_FIELD_TYPE)
+CLUSTER_NAME_COLUMN = InvoiceColumn(name=CLUSTER_NAME_FIELD, dtype=STRING_FIELD_TYPE)
+IS_COURSE_COLUMN = InvoiceColumn(
+    name=IS_COURSE_FIELD, dtype=BOOL_FIELD_TYPE, default_value=False
+)
+###
+
 
 @dataclass
 class Invoice:
     export_columns_list = list()
     exported_columns_map = dict()
+    initializes_columns = tuple()
+    operates_on_columns = tuple()
 
     invoice_month: str
     data: pandas.DataFrame
     name: str = ""
     export_data = None
 
     def process(self):
+        self._init_columns()
         self._prepare()
         self._process()
         self._prepare_export()
@@ -93,6 +171,20 @@ def output_s3_key(self) -> str:
     def output_s3_archive_key(self):
         return f"Invoices/{self.invoice_month}/Archive/{self.name} {self.invoice_month} {util.get_iso8601_time()}.csv"
 
+    def _init_columns(self):
+        """Initializes columns specified in `initializes_columns` and cast them to appropriate types
+
+        If column already exists, only do casting
+        If no default value is given, column initialized to None
+        """
+        for field in self.initializes_columns:
+            if field.name not in self.data.columns:
+                field_default = field.default_value
+                if field.default_initializer:
+                    field_default = field.default_initializer(self.data)
+                self.data[field.name] = field_default
+            self.data = self.data.astype({field.name: field.dtype})
+
     def _prepare(self):
         """Prepares the data for processing.
 

process_report/loader.py

@@ -112,6 +112,13 @@ def get_alias_map(self) -> dict:
     def load_dataframe(self, filepath: str) -> pandas.DataFrame:
         return pandas.read_csv(filepath)
 
+    @functools.lru_cache
+    def load_prepay_credits(self) -> pandas.DataFrame:
+        prepay_df = self.load_dataframe(invoice_settings.prepay_credits_filepath)
+        return prepay_df.astype(
+            {invoice.PREPAY_CREDIT_FIELD: invoice.BALANCE_FIELD_TYPE}
+        )
+
     @functools.lru_cache
     def _load_pi_config(self, filepath: str) -> list[dict]:
         with open(filepath) as file:

process_report/process_report.py

@@ -22,6 +22,7 @@
 )
 from process_report.processors import (
     coldfront_fetch_processor,
+    validate_input_column_processor,
     validate_pi_alias_processor,
     add_institution_processor,
     lenovo_processor,
@@ -33,6 +34,20 @@
     validate_cluster_name_processor,
 )
 
+PROCESSING_ORDER = [
+    validate_input_column_processor.ValidateInputColumnsProcessor,
+    validate_cluster_name_processor.ValidateClusterNameProcessor,
+    coldfront_fetch_processor.ColdfrontFetchProcessor,
+    validate_pi_alias_processor.ValidatePIAliasProcessor,
+    add_institution_processor.AddInstitutionProcessor,
+    lenovo_processor.LenovoProcessor,
+    validate_billable_pi_processor.ValidateBillablePIsProcessor,
+    pi_su_credit_processor.PISUCreditProcessor,
+    new_pi_credit_processor.NewPICreditProcessor,
+    bu_subsidy_processor.BUSubsidyProcessor,
+    prepayment_processor.PrepaymentProcessor,
+]
+
 
 PI_S3_FILEPATH = "PIs/PI.csv"
 ALIAS_S3_FILEPATH = "PIs/alias.csv"
@@ -66,20 +81,7 @@ def main():
 
     ### Preliminary processing
     processed_data = process_merged_dataframe(
-        invoice_month,
-        merged_dataframe,
-        [
-            validate_cluster_name_processor.ValidateClusterNameProcessor,
-            coldfront_fetch_processor.ColdfrontFetchProcessor,
-            validate_pi_alias_processor.ValidatePIAliasProcessor,
-            add_institution_processor.AddInstitutionProcessor,
-            lenovo_processor.LenovoProcessor,
-            validate_billable_pi_processor.ValidateBillablePIsProcessor,
-            pi_su_credit_processor.PISUCreditProcessor,
-            new_pi_credit_processor.NewPICreditProcessor,
-            bu_subsidy_processor.BUSubsidyProcessor,
-            prepayment_processor.PrepaymentProcessor,
-        ],
+        invoice_month, merged_dataframe, PROCESSING_ORDER
     )
 
     ### Export invoices

process_report/processors/add_institution_processor.py

@@ -14,6 +14,12 @@
 
 @dataclass
 class AddInstitutionProcessor(processor.Processor):
+    operates_on_columns = (
+        invoice.INSTITUTION_COLUMN,
+        invoice.PI_COLUMN,
+        invoice.PROJECT_COLUMN,
+    )
+
     def _add_institution(self):
         """Determine every PI's institution name, logging any PI whose institution cannot be determined
         This is performed by `get_institution_from_pi()`, which tries to match the PI's username to

process_report/processors/bu_subsidy_processor.py

@@ -1,5 +1,4 @@
 from dataclasses import dataclass, field
-from decimal import Decimal
 
 from process_report.loader import loader
 from process_report.invoices import invoice
@@ -10,6 +9,19 @@
 class BUSubsidyProcessor(discount_processor.DiscountProcessor):
     IS_DISCOUNT_BY_NERC = False
 
+    initializes_columns = (invoice.PROJECT_NAME_COLUMN, invoice.SUBSIDY_COLUMN)
+    operates_on_columns = (
+        invoice.PROJECT_COLUMN,
+        invoice.PROJECT_NAME_COLUMN,
+        invoice.PI_COLUMN,
+        invoice.IS_BILLABLE_COLUMN,
+        invoice.MISSING_PI_COLUMN,
+        invoice.INSTITUTION_COLUMN,
+        invoice.PI_BALANCE_COLUMN,
+        invoice.SUBSIDY_COLUMN,
+        invoice.BALANCE_COLUMN,
+    )
+
     subsidy_amount: int = field(default_factory=loader.get_bu_subsidy_amount)
 
     def _prepare(self):
@@ -21,7 +33,6 @@ def get_project(row):
                 return project_alloc[: project_alloc.rfind("-")]
 
         self.data[invoice.PROJECT_NAME_FIELD] = self.data.apply(get_project, axis=1)
-        self.data[invoice.SUBSIDY_FIELD] = Decimal(0)
 
     def _process(self):
         self.data = self._apply_subsidy(self.data, self.subsidy_amount)

process_report/processors/coldfront_fetch_processor.py

@@ -34,6 +34,16 @@ class ColdfrontFetchProcessor(processor.Processor):
     )
     coldfront_data_filepath: str = invoice_settings.coldfront_api_filepath
 
+    initializes_columns = (invoice.IS_COURSE_COLUMN,)
+    operates_on_columns = (
+        invoice.PROJECT_COLUMN,
+        invoice.PROJECT_ID_COLUMN,
+        invoice.CLUSTER_NAME_COLUMN,
+        invoice.PI_COLUMN,
+        invoice.INSTITUTION_ID_COLUMN,
+        invoice.IS_COURSE_COLUMN,
+    )
+
     @functools.cached_property
     def coldfront_client(self):
         keycloak_url = os.environ.get("KEYCLOAK_URL", "https://keycloak.mss.mghpcc.org")
@@ -143,7 +153,6 @@ def _validate_allocation_data(self, allocation_data):
             )
 
     def _apply_allocation_data(self, allocation_data):
-        self.data[invoice.IS_COURSE_FIELD] = False
         for project_cluster_tuple, data in allocation_data.items():
             project_id, cluster_name = project_cluster_tuple
             mask = (self.data[invoice.PROJECT_ID_FIELD] == project_id) & (

process_report/processors/discount_processor.py

@@ -51,7 +51,7 @@ def apply_discount_on_project(remaining_discount_amount, project_i, project):
             remaining_project_balance = project[pi_balance_field]
             applied_discount = min(remaining_project_balance, remaining_discount_amount)
 
-            if invoice.at[project_i, discount_field] is None:
+            if pandas.isna(invoice.at[project_i, discount_field]):
                 invoice.at[project_i, discount_field] = applied_discount
             else:
                 invoice.at[project_i, discount_field] += applied_discount

process_report/processors/lenovo_processor.py

@@ -9,6 +9,14 @@
 class LenovoProcessor(processor.Processor):
     su_charge_info: dict = field(default_factory=loader.get_lenovo_su_charge_info)
 
+    initializes_columns = (invoice.SU_CHARGE_COLUMN, invoice.LENOVO_CHARGE_COLUMN)
+    operates_on_columns = (
+        invoice.SU_TYPE_COLUMN,
+        invoice.SU_HOURS_COLUMN,
+        invoice.SU_CHARGE_COLUMN,
+        invoice.LENOVO_CHARGE_COLUMN,
+    )
+
     def _apply_su_charge(self, data):
         for su_name, su_charge in self.su_charge_info.items():
             if su_name in data:

process_report/processors/new_pi_credit_processor.py

@@ -34,6 +34,19 @@ class NewPICreditProcessor(discount_processor.DiscountProcessor):
     ]
     IS_DISCOUNT_BY_NERC = True
 
+    operates_on_columns = (
+        invoice.CREDIT_COLUMN,
+        invoice.CREDIT_CODE_COLUMN,
+        invoice.BALANCE_COLUMN,
+        invoice.PI_BALANCE_COLUMN,
+        invoice.SU_TYPE_COLUMN,
+        invoice.IS_BILLABLE_COLUMN,
+        invoice.MISSING_PI_COLUMN,
+        invoice.INSTITUTION_COLUMN,
+        invoice.COST_COLUMN,
+        invoice.PI_COLUMN,
+    )
+
     old_pi_filepath: str = field(
         default_factory=lambda: loader.get_remote_filepath(
             invoice_settings.pi_remote_filepath
@@ -176,10 +189,7 @@ def _apply_credits_new_pi(
                 credit_eligible_projects[invoice.PI_FIELD] == pi
             ]
 
-            if pi_age > 1:
-                for i, row in pi_projects.iterrows():
-                    data.at[i, invoice.BALANCE_FIELD] = row[invoice.COST_FIELD]
-            else:
+            if pi_age <= 1:
                 if pi_age == 0:
                     old_pi_df = self._upsert_pi_entry(
                         old_pi_df,
@@ -226,10 +236,6 @@ def _apply_credits_new_pi(
         return (data, old_pi_df)
 
     def _prepare(self):
-        self.data[invoice.CREDIT_FIELD] = None
-        self.data[invoice.CREDIT_CODE_FIELD] = None
-        self.data[invoice.PI_BALANCE_FIELD] = self.data[invoice.COST_FIELD]
-        self.data[invoice.BALANCE_FIELD] = self.data[invoice.COST_FIELD]
         self.old_pi_df = self._load_old_pis(self.old_pi_filepath)
 
     def _process(self):

process_report/processors/pi_su_credit_processor.py

@@ -25,6 +25,22 @@ class PISUCreditProcessor(discount_processor.DiscountProcessor):
     IS_DISCOUNT_BY_NERC = True
     PI_SU_CREDIT_CODE = "0005"
 
+    initializes_columns = (
+        invoice.CREDIT_COLUMN,
+        invoice.CREDIT_CODE_COLUMN,
+        invoice.PI_BALANCE_COLUMN,
+        invoice.BALANCE_COLUMN,
+    )
+    operates_on_columns = (
+        invoice.SU_TYPE_COLUMN,
+        invoice.PI_COLUMN,
+        invoice.COST_COLUMN,
+        invoice.CREDIT_COLUMN,
+        invoice.CREDIT_CODE_COLUMN,
+        invoice.PI_BALANCE_COLUMN,
+        invoice.BALANCE_COLUMN,
+    )
+
     pi_su_mapping: dict[str, list[str]] = field(
         default_factory=loader.get_pi_non_billed_su_types
     )