improve GapBuffer test coverage

test/src/test_GapBuffer.cc

@@ -1,6 +1,7 @@
 #include "gtest/gtest.h"
 #include "GapBuffer.h"
 #include "System.h"
+#include <string>
 
 TEST(GapBufferTest, creates_an_empty_buffer)
 {
@@ -22,12 +23,16 @@ TEST(GapBufferTest, allows_inserting)
     GapBuffer gp;
 
     gp.insert(0u, (const uint8_t *)"test", 4u);
-    EXPECT_EQ("test", gp.get_string());
+    EXPECT_EQ('s', *gp.address(2u));
     EXPECT_EQ(4u, gp.size());
+    EXPECT_EQ("test", gp.get_string());
 
     gp.insert(2u, (const uint8_t *)"12", 2u);
-    EXPECT_EQ("te12st", gp.get_string());
+    /* The gap should be between the '2' and 's' now */
+    EXPECT_GT(gp.address(4u) - gp.address(3u), 100u);
+    EXPECT_EQ('s', *gp.address(4u));
     EXPECT_EQ(6u, gp.size());
+    EXPECT_EQ("te12st", gp.get_string());
 
     gp.insert(0u, (const uint8_t *)"-", 1u);
     EXPECT_EQ("-te12st", gp.get_string());
@@ -37,3 +42,18 @@ TEST(GapBufferTest, allows_inserting)
     EXPECT_EQ("-te12st!", gp.get_string());
     EXPECT_EQ(8u, gp.size());
 }
+
+TEST(GapBufferTest, allocates_more_memory_and_copies_buffer_contents_when_needed)
+{
+    GapBuffer gp;
+    std::string s("ABCD");
+
+    gp.insert(0u, (const uint8_t *)"ABCDEFGH", 8u);
+    for (size_t i = 0u; i < (80u * 1024u); i++)
+    {
+        gp.insert(4u, (const uint8_t *)"-", 1u);
+        s += "-";
+    }
+    s += "EFGH";
+    EXPECT_EQ(s, gp.get_string());
+}