Tests: Test FixedArray completely

Except for tangential accessors such as data(), there is no more feature
of FixedArray that is untested after this large expansion of its test
cases. These tests, with the help of the new NoAllocationGuard, also
test the allocation contract that was fixated in the last commit.

Hopefully this builds confidence in future Kernel uses of FixedArray
as well as its establishment in the real-time parts of the audio
subsystem. I'm excited :^)

2 files changed, 58 insertions, 3 deletions

diff --git a/AK/NoAllocationGuard.h b/AK/NoAllocationGuard.h
index 19356541dd..e009644196 100644
--- a/AK/NoAllocationGuard.h
+++ b/AK/NoAllocationGuard.h
@@ -58,7 +58,7 @@ private:
 #endif
     }
 
-    bool m_allocation_enabled_previously;
+    bool m_allocation_enabled_previously { true };
 };
 
 }
diff --git a/Tests/AK/TestFixedArray.cpp b/Tests/AK/TestFixedArray.cpp
index 872f97767b..b0c6ca8f31 100644
--- a/Tests/AK/TestFixedArray.cpp
+++ b/Tests/AK/TestFixedArray.cpp
@@ -4,14 +4,16 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <LibTest/TestCase.h>
 #include <LibTest/TestSuite.h>
 
 #include <AK/FixedArray.h>
-#include <AK/String.h>
+#include <AK/NoAllocationGuard.h>
 
 TEST_CASE(construct)
 {
-    EXPECT(FixedArray<int>().size() == 0);
+    EXPECT_EQ(FixedArray<int>().size(), 0u);
+    EXPECT_EQ(FixedArray<int>::must_create_but_fixme_should_propagate_errors(1985).size(), 1985u);
 }
 
 TEST_CASE(ints)
@@ -24,3 +26,56 @@ TEST_CASE(ints)
     EXPECT_EQ(ints[1], 1);
     EXPECT_EQ(ints[2], 2);
 }
+
+TEST_CASE(swap)
+{
+    FixedArray<int> first = FixedArray<int>::must_create_but_fixme_should_propagate_errors(4);
+    FixedArray<int> second = FixedArray<int>::must_create_but_fixme_should_propagate_errors(5);
+    first[3] = 1;
+    second[3] = 2;
+    first.swap(second);
+    EXPECT_EQ(first.size(), 5u);
+    EXPECT_EQ(second.size(), 4u);
+    EXPECT_EQ(first[3], 2);
+    EXPECT_EQ(second[3], 1);
+}
+
+TEST_CASE(move)
+{
+    FixedArray<int> moved_from_array = FixedArray<int>::must_create_but_fixme_should_propagate_errors(6);
+    FixedArray<int> moved_to_array(move(moved_from_array));
+    EXPECT_EQ(moved_to_array.size(), 6u);
+    EXPECT_EQ(moved_from_array.size(), 0u);
+}
+
+TEST_CASE(no_allocation)
+{
+    FixedArray<int> array = FixedArray<int>::must_create_but_fixme_should_propagate_errors(5);
+    EXPECT_NO_CRASH("Assigments", [&] {
+        NoAllocationGuard guard;
+        array[0] = 0;
+        array[1] = 1;
+        array[2] = 2;
+        array[4] = array[1];
+        array[3] = array[0] + array[2];
+        return Test::Crash::Failure::DidNotCrash;
+    });
+
+    EXPECT_NO_CRASH("Move", [&] {
+        FixedArray<int> moved_from_array = FixedArray<int>::must_create_but_fixme_should_propagate_errors(6);
+        NoAllocationGuard guard;
+        FixedArray<int> moved_to_array(move(moved_from_array));
+        // We need to ensure that this destructor runs before the FixedArray destructor.
+        guard.~NoAllocationGuard();
+        return Test::Crash::Failure::DidNotCrash;
+    });
+
+    EXPECT_NO_CRASH("Swap", [&] {
+        FixedArray<int> target_for_swapping;
+        {
+            NoAllocationGuard guard;
+            array.swap(target_for_swapping);
+        }
+        return Test::Crash::Failure::DidNotCrash;
+    });
+}