Fix memory leak in test "VegProdConstructor"

- close #205

- remove leak suppression in "SW_VPD_construct" that is no longer needed

- the test "VegProdStructTest.VegProdConstructor" (previously named, as of v7.0.0, "VegTest.Constructor") now (1) uses a local copy of SW_VEGPROD and (2) calls `SW_VPD_deconstruct()` to avoid a memory leak

- Previously, the test used `SW_All.VegProd` or a global variable (for which `SW_VPD_construct()` has already been called once and allocated memory, e.g., during the test fixture's `SetUp()` or `Reset_SOILWAT2_after_UnitTest()`); then the (second) call to `SW_VPD_construct()` would allocate memory a second time (thus the memory previously allocated is leaked).
However, the call to `SW_VPD_deconstruct()` (either in the test or during the test fixture's `TearDown()` or `Reset_SOILWAT2_after_UnitTest()`) will de-allocate only the most recently allocated memory (and, if called again, was seeing only NULL).

- before this commit, I was getting with `MallocStackLogging=1 MallocStackLoggingNoCompact=1 MallocScribble=1 MallocPreScribble=1 MallocCheckHeapStart=0 MallocCheckHeapEach=0 leaks -quiet -atExit -- bin/sw_test`
> 7 leaks for 896 total leaked bytes.
    7 (896 bytes) << TOTAL >>
      1 (128 bytes) ROOT LEAK: 0x600000cb0100 [128]
      1 (128 bytes) ROOT LEAK: 0x600000cb0180 [128]
      1 (128 bytes) ROOT LEAK: 0x600000cb0200 [128]
      1 (128 bytes) ROOT LEAK: 0x600000cb0280 [128]
      1 (128 bytes) ROOT LEAK: 0x600000cb0300 [128]
      1 (128 bytes) ROOT LEAK: 0x600000cb0380 [128]
      1 (128 bytes) ROOT LEAK: 0x600000cb0400 [128]

- after this commit, I'm getting
> 0 leaks for 0 total leaked bytes.

.LSAN_suppr.txt

@@ -3,8 +3,5 @@
 
 # These are known leaks that await fixing
 
-# https://github.com/DrylandEcology/SOILWAT2/issues/205
-leak:SW_VPD_construct
-
 # on Apple arm64: https://github.com/google/sanitizers/issues/1501
 leak:realizeClassWithoutSwift

NEWS.md

@@ -4,6 +4,7 @@
 * Bugfixes
     * Fix an error where a pointer was freed even though it was not allocated
       (issue #356; @dschlaep).
+    * Fix memory leak in test of `SW_VPD_construct()` (issue #205; @dschlaep).
 
 # SOILWAT2 v7.0.0
 * This version produces nearly identical simulation output

tests/gtests/test_SW_VegProd.cc

@@ -114,18 +114,38 @@ namespace {
   int k;
 
   // Test the SW_VEGPROD constructor 'SW_VPD_construct'
-  TEST_F(AllTest, VegProdConstructor) {
-    SW_VPD_construct(&SW_All.VegProd, &LogInfo);
-    SW_VPD_init_run(&SW_All.VegProd, &SW_All.Weather,
-                    &SW_All.Model, SW_All.Site.latitude, &LogInfo);
+  TEST_F(VegProdStructTest, VegProdConstructor) {
+    // This test requires a local copy of SW_VEGPROD to avoid a memory leak
+    // (see issue #205)
+    // -- If using `SW_All.VegProd` or a global variable
+    // (for which `SW_VPD_construct()` has already been called once, e.g.,
+    // during the test fixture's `SetUp()`), then this (second) call to
+    // `SW_VPD_construct()` would allocate memory a second time
+    // while `SW_VPD_deconstruct()` will de-allocate memory only once
+    // (the call to `SW_VPD_deconstruct()`during the test fixture's `TearDown()`
+    // would see only NULL and thus not de-allocate the required second time
+    // to avoid a leak)
+    SW_VEGPROD SW_VegProd;
+
+    SW_VPD_construct(&SW_VegProd, &LogInfo); // allocates memory
+
+    SW_VPD_init_run(
+      &SW_VegProd,
+      &SW_All.Weather,
+      &SW_All.Model,
+      SW_All.Site.latitude,
+      &LogInfo
+    );
 
     ForEachVegType(k) {
-      EXPECT_DOUBLE_EQ(1., SW_All.VegProd.veg[k].co2_multipliers[BIO_INDEX][0]);
-      EXPECT_DOUBLE_EQ(1., SW_All.VegProd.veg[k].co2_multipliers[BIO_INDEX][MAX_NYEAR - 1]);
+      EXPECT_DOUBLE_EQ(1., SW_VegProd.veg[k].co2_multipliers[BIO_INDEX][0]);
+      EXPECT_DOUBLE_EQ(1., SW_VegProd.veg[k].co2_multipliers[BIO_INDEX][MAX_NYEAR - 1]);
 
-      EXPECT_DOUBLE_EQ(1., SW_All.VegProd.veg[k].co2_multipliers[WUE_INDEX][0]);
-      EXPECT_DOUBLE_EQ(1., SW_All.VegProd.veg[k].co2_multipliers[WUE_INDEX][MAX_NYEAR - 1]);
+      EXPECT_DOUBLE_EQ(1., SW_VegProd.veg[k].co2_multipliers[WUE_INDEX][0]);
+      EXPECT_DOUBLE_EQ(1., SW_VegProd.veg[k].co2_multipliers[WUE_INDEX][MAX_NYEAR - 1]);
     }
+
+    SW_VPD_deconstruct(&SW_VegProd);
   }