feat: pricing helper with regression tests

Jenkinsfile

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+// Test gate for the Hermes code-repair demo.
+podTemplate(cloud: 'kubernetes', yaml: """
+apiVersion: v1
+kind: Pod
+spec:
+  serviceAccountName: jenkins
+  securityContext:
+    runAsUser: 1000
+    runAsGroup: 1000
+    fsGroup: 1000
+    fsGroupChangePolicy: "OnRootMismatch"
+  nodeSelector:
+    kubernetes.io/arch: arm64
+    node-role.kubernetes.io/worker: "true"
+  containers:
+    - name: python
+      image: python:3.12-slim
+      command: ["sleep"]
+      args: ["3600"]
+      resources:
+        requests:
+          cpu: 100m
+          memory: 128Mi
+        limits:
+          cpu: 500m
+          memory: 512Mi
+""") {
+  node(POD_LABEL) {
+    container('python') {
+      stage('Checkout') {
+        checkout scm
+      }
+      stage('tests') {
+        sh 'pip install --quiet pytest'
+        sh 'python -m pytest -v --junitxml=build/junit.xml'
+      }
+    }
+  }
+}

README.md

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+# hermes-code-demo
+
+Deterministic source-defect fixture for the Hermes automated triage demo.
+
+`src/discount.py` holds one small pricing helper covered by `tests/test_discount.py`.
+The demo introduces a one-line defect on a branch, Jenkins fails the test gate,
+Ariadne collects the evidence, and Hermes proposes a minimal patch that Ariadne
+validates and pushes as a pull request for human review. Nothing merges
+automatically.

pytest.ini

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+[pytest]
+pythonpath = .

src/discount.py

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+"""Order pricing helpers for the Hermes code-repair demo."""
+
+
+def apply_discount(subtotal: float, percent: float) -> float:
+    """Return the subtotal reduced by a whole-number discount percent.
+
+    Inputs: the order subtotal and a discount percent between 0 and 100.
+    Outputs: the discounted total, rounded to two decimal places.
+    """
+
+    if percent < 0 or percent > 100:
+        raise ValueError("percent must be between 0 and 100")
+    return round(subtotal * (1 - percent / 100), 2)

tests/test_discount.py

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+"""Regression tests for the demo pricing helper."""
+
+import pytest
+
+from src.discount import apply_discount
+
+
+def test_no_discount_returns_subtotal() -> None:
+    assert apply_discount(100.0, 0) == 100.0
+
+
+def test_ten_percent_off() -> None:
+    assert apply_discount(100.0, 10) == 90.0
+
+
+def test_full_discount_is_free() -> None:
+    assert apply_discount(59.99, 100) == 0.0
+
+
+def test_fractional_rounding() -> None:
+    assert apply_discount(19.99, 15) == 16.99
+
+
+def test_rejects_out_of_range_percent() -> None:
+    with pytest.raises(ValueError):
+        apply_discount(10.0, 101)