Fix panic when canonicalizing a jobspec with incorrect job type.

When canonicalizing the ReschedulePolicy a panic was possible if
the passed job type was not valid. This change protects against
this possibility, in a verbose way to ensure the code path is
clear.

api/tasks.go

@@ -217,6 +217,19 @@ func NewDefaultReschedulePolicy(jobType string) *ReschedulePolicy {
 			MaxDelay:      timeToPtr(0),
 			Unlimited:     boolToPtr(false),
 		}
+
+	default:
+		// GH-7203: it is possible an unknown job type is passed to this
+		// function and we need to ensure a non-nil object is returned so that
+		// the canonicalization runs without panicking.
+		dp = &ReschedulePolicy{
+			Attempts:      intToPtr(0),
+			Interval:      timeToPtr(0),
+			Delay:         timeToPtr(0),
+			DelayFunction: stringToPtr(""),
+			MaxDelay:      timeToPtr(0),
+			Unlimited:     boolToPtr(false),
+		}
 	}
 	return dp
 }

api/tasks_test.go

@@ -638,3 +638,67 @@ func TestSpread_Canonicalize(t *testing.T) {
 		})
 	}
 }
+
+func Test_NewDefaultReschedulePolicy(t *testing.T) {
+	testCases := []struct {
+		desc         string
+		inputJobType string
+		expected     *ReschedulePolicy
+	}{
+		{
+			desc:         "service job type",
+			inputJobType: "service",
+			expected: &ReschedulePolicy{
+				Attempts:      intToPtr(0),
+				Interval:      timeToPtr(0),
+				Delay:         timeToPtr(30 * time.Second),
+				DelayFunction: stringToPtr("exponential"),
+				MaxDelay:      timeToPtr(1 * time.Hour),
+				Unlimited:     boolToPtr(true),
+			},
+		},
+		{
+			desc:         "batch job type",
+			inputJobType: "batch",
+			expected: &ReschedulePolicy{
+				Attempts:      intToPtr(1),
+				Interval:      timeToPtr(24 * time.Hour),
+				Delay:         timeToPtr(5 * time.Second),
+				DelayFunction: stringToPtr("constant"),
+				MaxDelay:      timeToPtr(0),
+				Unlimited:     boolToPtr(false),
+			},
+		},
+		{
+			desc:         "system job type",
+			inputJobType: "system",
+			expected: &ReschedulePolicy{
+				Attempts:      intToPtr(0),
+				Interval:      timeToPtr(0),
+				Delay:         timeToPtr(0),
+				DelayFunction: stringToPtr(""),
+				MaxDelay:      timeToPtr(0),
+				Unlimited:     boolToPtr(false),
+			},
+		},
+		{
+			desc:         "unrecognised job type",
+			inputJobType: "unrecognised",
+			expected: &ReschedulePolicy{
+				Attempts:      intToPtr(0),
+				Interval:      timeToPtr(0),
+				Delay:         timeToPtr(0),
+				DelayFunction: stringToPtr(""),
+				MaxDelay:      timeToPtr(0),
+				Unlimited:     boolToPtr(false),
+			},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.desc, func(t *testing.T) {
+			actual := NewDefaultReschedulePolicy(tc.inputJobType)
+			assert.Equal(t, tc.expected, actual)
+		})
+	}
+}