Bug 799832 - Investment Lots report crashes on a lot with a sale but no purchase

A lot that has a share-reducing (sale) split but no purchase split left
the lot's latest-bought-split-date null, which crashed the report with
"Wrong type (expecting exact integer): ()" when it computed the holding
period via gnc:date-year-delta -> gnc-localtime.

Guard the two year-delta call sites against a null bought date, and treat
a negative holding period (a purchase dated after its sale) as having no
meaningful CAGR. Skip the gains-mismatch warning for lots with no
purchase, whose basis is undefined; such lots are already flagged by the
negative-balance warning.

Add regression tests covering a sale-without-purchase lot and a
buy-after-sell lot.

gnucash/report/reports/standard/investment-lots.scm

@@ -452,7 +452,10 @@ Returns #f if calculation is not possible, otherwise returns decimal CAGR."
           (gnc-numeric-negative-p basis)
           (gnc-numeric-negative-p end-value)
           (eq? years #f)
-          (zero? years))
+          (zero? years)
+          ;; Negative holding period (e.g. a purchase dated after the
+          ;; sale) has no meaningful CAGR.
+          (negative? years))
     #f
     (- (expt (/ (gnc-numeric-to-double end-value)
                (gnc-numeric-to-double basis))
@@ -1472,9 +1475,10 @@ Returns #t if held >= long-term-years, #f otherwise."
                   (years-held
                     (cond
                       (is-lot-row
-                        (gnc:date-year-delta
-                          latest-bought-split-date
-                          to-date))
+                        (and (not (null? latest-bought-split-date))
+                             (gnc:date-year-delta
+                               latest-bought-split-date
+                               to-date)))
                       (else #f)))
                   (unrealized-cagr
                       (cond
@@ -1583,8 +1587,11 @@ Returns #t if held >= long-term-years, #f otherwise."
               '())
 
             ;; Warn if the report-computed gains do not match the
-            ;; "Realized Gain/Loss" split.
-            (if warn-if-gains-mismatch
+            ;; "Realized Gain/Loss" split.  Skip lots with no purchase: their
+            ;; basis is undefined so the computed gain is not meaningful (and
+            ;; the negative-balance warning above already flags them).
+            (if (and warn-if-gains-mismatch
+                     (> bought-split-count 0))
               (let* ((all-terms-realized-gain (gnc-numeric-add-fixed
                                                 short-term-realized-gain
                                                 long-term-realized-gain))
@@ -1857,9 +1864,13 @@ Returns #t if held >= long-term-years, #f otherwise."
           (cond
             ((>= trans-date from-date)
               (let* ((years-held
-                        (gnc:date-year-delta
-                            latest-bought-split-date
-                            trans-date))
+                        ;; latest-bought-split-date is null if this sale
+                        ;; precedes any purchase (e.g. a malformed or
+                        ;; oversold lot); skip the CAGR in that case.
+                        (and (not (null? latest-bought-split-date))
+                             (gnc:date-year-delta
+                                latest-bought-split-date
+                                trans-date)))
                      (cagr (get-cagr basis value years-held)))
                 ;; Remember if a sale within the report window causes the
                 ;; lot's balance to go negative.

gnucash/report/reports/standard/test/test-investment-lots.scm

@@ -7,6 +7,7 @@
 (use-modules (srfi srfi-64))
 (use-modules (gnucash engine))
 (use-modules (gnucash app-utils))
+(use-modules (sxml xpath))
 
 ;; UUID for the investment-lots report
 (define uuid "ab2acc24afd14630a551f98f1a35fa81")
@@ -368,6 +369,117 @@
 
       account-alist)))
 
+;; A malformed lot with a sale but no purchase.  Its balance ends negative
+;; and it has no bought split, which previously crashed the report when it
+;; computed a holding period from a null bought date.
+(define (create-sale-without-purchase-test-data)
+  (let* ((book (gnc-get-current-book))
+         (env (create-test-env))
+         (USD (mnemonic->commodity "USD"))
+         (comm-table (gnc-commodity-table-get-table book))
+         (AAPL (gnc-commodity-new book "Apple" "NASDAQ" "AAPL" "" 1))
+         (structure
+           (list "Root" (list (cons 'type ACCT-TYPE-ASSET)
+                              (cons 'commodity USD))
+                 (list "Assets"
+                       (list "Broker" (list (cons 'commodity USD))
+                             (list "Cash" (list (cons 'commodity USD)))
+                             (list "AAPL" (list (cons 'commodity AAPL)
+                                                (cons 'type ACCT-TYPE-STOCK))))))))
+
+    (gnc-commodity-table-insert comm-table AAPL)
+
+    (let* ((account-alist (env-create-account-structure-alist env structure))
+           (cash (cdr (assoc "Cash" account-alist)))
+           (aapl-acct (cdr (assoc "AAPL" account-alist)))
+           (lot (gnc-lot-new book))
+           (sale-txn (xaccMallocTransaction book))
+           (sale-stock (xaccMallocSplit book))
+           (sale-cash (xaccMallocSplit book)))
+
+      ;; Sell 25 shares for $3,000 into a lot that was never bought into.
+      (xaccTransBeginEdit sale-txn)
+      (xaccTransSetCurrency sale-txn USD)
+      (xaccTransSetDate sale-txn 1 3 2020)
+      (xaccTransSetDescription sale-txn "Sell AAPL (no purchase)")
+      (xaccSplitSetAccount sale-stock aapl-acct)
+      (xaccSplitSetAmount sale-stock (gnc-numeric-create -25 1))
+      (xaccSplitSetValue sale-stock (gnc-numeric-create -3000 1))
+      (xaccSplitSetParent sale-stock sale-txn)
+      (gnc-lot-add-split lot sale-stock)
+      (xaccSplitSetAccount sale-cash cash)
+      (xaccSplitSetAmount sale-cash (gnc-numeric-create 3000 1))
+      (xaccSplitSetValue sale-cash (gnc-numeric-create 3000 1))
+      (xaccSplitSetParent sale-cash sale-txn)
+      (xaccTransCommitEdit sale-txn)
+
+      account-alist)))
+
+;; A lot whose purchase is dated after its sale.  The holding period is
+;; negative, which previously produced a bogus CAGR (and crashed on the
+;; null bought date seen while processing the earlier sale).
+(define (create-buy-after-sell-test-data)
+  (let* ((book (gnc-get-current-book))
+         (env (create-test-env))
+         (USD (mnemonic->commodity "USD"))
+         (comm-table (gnc-commodity-table-get-table book))
+         (AAPL (gnc-commodity-new book "Apple" "NASDAQ" "AAPL" "" 1))
+         (structure
+           (list "Root" (list (cons 'type ACCT-TYPE-ASSET)
+                              (cons 'commodity USD))
+                 (list "Assets"
+                       (list "Broker" (list (cons 'commodity USD))
+                             (list "Cash" (list (cons 'commodity USD)))
+                             (list "AAPL" (list (cons 'commodity AAPL)
+                                                (cons 'type ACCT-TYPE-STOCK))))))))
+
+    (gnc-commodity-table-insert comm-table AAPL)
+
+    (let* ((account-alist (env-create-account-structure-alist env structure))
+           (cash (cdr (assoc "Cash" account-alist)))
+           (aapl-acct (cdr (assoc "AAPL" account-alist)))
+           (lot (gnc-lot-new book))
+           (sale-txn (xaccMallocTransaction book))
+           (sale-stock (xaccMallocSplit book))
+           (sale-cash (xaccMallocSplit book))
+           (buy-txn (xaccMallocTransaction book))
+           (buy-stock (xaccMallocSplit book))
+           (buy-cash (xaccMallocSplit book)))
+
+      ;; Sell 25 shares for $3,000 in 2019.
+      (xaccTransBeginEdit sale-txn)
+      (xaccTransSetCurrency sale-txn USD)
+      (xaccTransSetDate sale-txn 1 1 2019)
+      (xaccTransSetDescription sale-txn "Sell AAPL (before buy)")
+      (xaccSplitSetAccount sale-stock aapl-acct)
+      (xaccSplitSetAmount sale-stock (gnc-numeric-create -25 1))
+      (xaccSplitSetValue sale-stock (gnc-numeric-create -3000 1))
+      (xaccSplitSetParent sale-stock sale-txn)
+      (gnc-lot-add-split lot sale-stock)
+      (xaccSplitSetAccount sale-cash cash)
+      (xaccSplitSetAmount sale-cash (gnc-numeric-create 3000 1))
+      (xaccSplitSetValue sale-cash (gnc-numeric-create 3000 1))
+      (xaccSplitSetParent sale-cash sale-txn)
+      (xaccTransCommitEdit sale-txn)
+
+      ;; Buy 100 shares for $5,000 in 2020, i.e. after the sale.
+      (xaccTransBeginEdit buy-txn)
+      (xaccTransSetCurrency buy-txn USD)
+      (xaccTransSetDate buy-txn 1 1 2020)
+      (xaccTransSetDescription buy-txn "Buy AAPL (after sale)")
+      (xaccSplitSetAccount buy-stock aapl-acct)
+      (xaccSplitSetAmount buy-stock (gnc-numeric-create 100 1))
+      (xaccSplitSetValue buy-stock (gnc-numeric-create 5000 1))
+      (xaccSplitSetParent buy-stock buy-txn)
+      (gnc-lot-add-split lot buy-stock)
+      (xaccSplitSetAccount buy-cash cash)
+      (xaccSplitSetAmount buy-cash (gnc-numeric-create -5000 1))
+      (xaccSplitSetValue buy-cash (gnc-numeric-create -5000 1))
+      (xaccSplitSetParent buy-cash buy-txn)
+      (xaccTransCommitEdit buy-txn)
+
+      account-alist)))
+
 (define (find-col-index labels target)
   (let loop ((rest labels) (i 1))
     (cond
@@ -381,6 +493,11 @@
     (or (pred (car lst))
         (list-any pred (cdr lst)))))
 
+;; #t if any text node in the sxml tree contains the given substring.
+(define (sxml-text-contains? sxml substr)
+  (list-any (lambda (s) (and (string? s) (string-contains s substr)))
+            ((sxpath '(// *text*)) sxml)))
+
 (define (test-investment-lots)
   ;; Test rendering with various configurations
   (test-group-with-cleanup "rendering-tests"
@@ -833,4 +950,42 @@
       (test-assert "realized-gain-equal-equivalent-baseline"
         (equal? base-realized-values rev-realized-values))))
 
+    (gnc-clear-current-session))
+
+  ;; A lot with a sale but no purchase must render (not crash) and surface
+  ;; the negative-balance warning rather than a meaningless gains mismatch.
+  (test-group-with-cleanup "sale-without-purchase-renders"
+    (let* ((account-alist (create-sale-without-purchase-test-data))
+           (options (gnc:make-report-options uuid)))
+      (set-option! options "General" "Start date"
+                   (cons 'absolute (gnc-dmy2time64 01 01 2019)))
+      (set-option! options "General" "End date"
+                   (cons 'absolute (gnc-dmy2time64 31 12 2021)))
+      (set-option! options "Validation"
+                   "Warn if a lot's balance drops below zero" #t)
+      (set-option! options "Validation"
+                   "Warn if the 'Realized Gain/Loss' split(s) sum does not match the computed gains" #t)
+      (let ((sxml (options->sxml options "sale-without-purchase")))
+        (test-assert "renders-without-crash" sxml)
+        (test-assert "negative-balance-warning-shown"
+          (sxml-text-contains? sxml "balance is negative"))
+        (test-assert "no-gains-mismatch-warning"
+          (not (sxml-text-contains? sxml "is not equal to the")))))
+
+    (gnc-clear-current-session))
+
+  ;; A lot whose purchase is dated after its sale must render without crashing
+  ;; on the negative holding period (no bogus CAGR, no null-date error).
+  (test-group-with-cleanup "buy-after-sell-renders"
+    (let* ((account-alist (create-buy-after-sell-test-data))
+           (options (gnc:make-report-options uuid)))
+      (set-option! options "General" "Start date"
+                   (cons 'absolute (gnc-dmy2time64 01 01 2018)))
+      (set-option! options "General" "End date"
+                   (cons 'absolute (gnc-dmy2time64 31 12 2021)))
+      (set-option! options "Columns" "Show CAGR columns" #t)
+      (test-assert "renders-without-crash"
+        (render-report options "buy-after-sell")))
+
     (gnc-clear-current-session)))
+