From eca1ff7a9f784926c52533c81cb5403a2cb804d3 Mon Sep 17 00:00:00 2001
From: Tobias Pflug <tobias.pflug@gmail.com>
Date: Sun, 31 May 2020 01:05:05 +0200
Subject: [PATCH 1/2] Add tests for lru-cache.hh

---
 src/libutil/tests/lru-cache.cc | 130 +++++++++++++++++++++++++++++++++
 1 file changed, 130 insertions(+)
 create mode 100644 src/libutil/tests/lru-cache.cc

diff --git a/src/libutil/tests/lru-cache.cc b/src/libutil/tests/lru-cache.cc
new file mode 100644
index 000000000..598977a6d
--- /dev/null
+++ b/src/libutil/tests/lru-cache.cc
@@ -0,0 +1,130 @@
+#include "lru-cache.hh"
+#include <gtest/gtest.h>
+
+namespace nix {
+
+    /* ----------------------------------------------------------------------------
+     * size
+     * --------------------------------------------------------------------------*/
+
+    TEST(LRUCache, sizeOfEmptyCacheIsZero) {
+        LRUCache<std::string, std::string> c(10);
+        ASSERT_EQ(c.size(), 0);
+    }
+
+    TEST(LRUCache, sizeOfSingleElementCacheIsOne) {
+        LRUCache<std::string, std::string> c(10);
+        c.upsert("foo", "bar");
+        ASSERT_EQ(c.size(), 1);
+    }
+
+    /* ----------------------------------------------------------------------------
+     * upsert / get
+     * --------------------------------------------------------------------------*/
+
+    TEST(LRUCache, getFromEmptyCache) {
+        LRUCache<std::string, std::string> c(10);
+        auto val = c.get("x");
+        ASSERT_EQ(val.has_value(), false);
+    }
+
+    TEST(LRUCache, getExistingValue) {
+        LRUCache<std::string, std::string> c(10);
+        c.upsert("foo", "bar");
+        auto val = c.get("foo");
+        ASSERT_EQ(val, "bar");
+    }
+
+    TEST(LRUCache, getNonExistingValueFromNonEmptyCache) {
+        LRUCache<std::string, std::string> c(10);
+        c.upsert("foo", "bar");
+        auto val = c.get("another");
+        ASSERT_EQ(val.has_value(), false);
+    }
+
+    TEST(LRUCache, upsertOnZeroCapacityCache) {
+        LRUCache<std::string, std::string> c(0);
+        c.upsert("foo", "bar");
+        auto val = c.get("foo");
+        ASSERT_EQ(val.has_value(), false);
+    }
+
+    TEST(LRUCache, updateExistingValue) {
+        LRUCache<std::string, std::string> c(1);
+        c.upsert("foo", "bar");
+
+        auto val = c.get("foo");
+        ASSERT_EQ(val.value_or("error"), "bar");
+        ASSERT_EQ(c.size(), 1);
+
+        c.upsert("foo", "changed");
+        val = c.get("foo");
+        ASSERT_EQ(val.value_or("error"), "changed");
+        ASSERT_EQ(c.size(), 1);
+    }
+
+    TEST(LRUCache, overwriteOldestWhenCapacityIsReached) {
+        LRUCache<std::string, std::string> c(3);
+        c.upsert("one", "eins");
+        c.upsert("two", "zwei");
+        c.upsert("three", "drei");
+
+        ASSERT_EQ(c.size(), 3);
+        ASSERT_EQ(c.get("one").value_or("error"), "eins");
+
+        // exceed capacity
+        c.upsert("another", "whatever");
+
+        ASSERT_EQ(c.size(), 3);
+        // Retrieving "one" makes it the most recent element thus
+        // two will be the oldest one and thus replaced.
+        ASSERT_EQ(c.get("two").has_value(), false);
+        ASSERT_EQ(c.get("another").value(), "whatever");
+    }
+
+    /* ----------------------------------------------------------------------------
+     * clear
+     * --------------------------------------------------------------------------*/
+
+    TEST(LRUCache, clearEmptyCache) {
+        LRUCache<std::string, std::string> c(10);
+        c.clear();
+        ASSERT_EQ(c.size(), 0);
+    }
+
+    TEST(LRUCache, clearNonEmptyCache) {
+        LRUCache<std::string, std::string> c(10);
+        c.upsert("one", "eins");
+        c.upsert("two", "zwei");
+        c.upsert("three", "drei");
+        ASSERT_EQ(c.size(), 3);
+        c.clear();
+        ASSERT_EQ(c.size(), 0);
+    }
+
+    /* ----------------------------------------------------------------------------
+     * erase
+     * --------------------------------------------------------------------------*/
+
+    TEST(LRUCache, eraseFromEmptyCache) {
+        LRUCache<std::string, std::string> c(10);
+        c.erase("foo");
+        ASSERT_EQ(c.size(), 0);
+    }
+
+    TEST(LRUCache, eraseMissingFromNonEmptyCache) {
+        LRUCache<std::string, std::string> c(10);
+        c.upsert("one", "eins");
+        c.erase("foo");
+        ASSERT_EQ(c.size(), 1);
+        ASSERT_EQ(c.get("one").value_or("error"), "eins");
+    }
+
+    TEST(LRUCache, eraseFromNonEmptyCache) {
+        LRUCache<std::string, std::string> c(10);
+        c.upsert("one", "eins");
+        c.erase("one");
+        ASSERT_EQ(c.size(), 0);
+        ASSERT_EQ(c.get("one").value_or("empty"), "empty");
+    }
+}

From e9fee8e6a7ff8540a04620e7d75a987cfe89ab00 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 2 Jun 2020 12:06:59 +0200
Subject: [PATCH 2/2] src/libutil/tests/lru-cache.cc: Check erase()

Co-authored-by: James Lee <jbit@jbit.net>
---
 src/libutil/tests/lru-cache.cc | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/libutil/tests/lru-cache.cc b/src/libutil/tests/lru-cache.cc
index 598977a6d..091d3d5ed 100644
--- a/src/libutil/tests/lru-cache.cc
+++ b/src/libutil/tests/lru-cache.cc
@@ -108,14 +108,14 @@ namespace nix {
 
     TEST(LRUCache, eraseFromEmptyCache) {
         LRUCache<std::string, std::string> c(10);
-        c.erase("foo");
+        ASSERT_EQ(c.erase("foo"), false);
         ASSERT_EQ(c.size(), 0);
     }
 
     TEST(LRUCache, eraseMissingFromNonEmptyCache) {
         LRUCache<std::string, std::string> c(10);
         c.upsert("one", "eins");
-        c.erase("foo");
+        ASSERT_EQ(c.erase("foo"), false);
         ASSERT_EQ(c.size(), 1);
         ASSERT_EQ(c.get("one").value_or("error"), "eins");
     }
@@ -123,7 +123,7 @@ namespace nix {
     TEST(LRUCache, eraseFromNonEmptyCache) {
         LRUCache<std::string, std::string> c(10);
         c.upsert("one", "eins");
-        c.erase("one");
+        ASSERT_EQ(c.erase("one"), true);
         ASSERT_EQ(c.size(), 0);
         ASSERT_EQ(c.get("one").value_or("empty"), "empty");
     }