Finish unit test for CFX_ByteStringC class.

This fixes a few cut-n-paste errors in the previous version, plus
adds more corner cases.  The implementation is fixed to handle a
few of these that failed.

R=brucedawson@chromium.org

Review URL: https://codereview.chromium.org/808553013

3 files changed, 177 insertions, 17 deletions

diff --git a/core/include/fxcrt/fx_string.h b/core/include/fxcrt/fx_string.h
index 524d7efde5..eae1c15a04 100644
--- a/core/include/fxcrt/fx_string.h
+++ b/core/include/fxcrt/fx_string.h
@@ -15,6 +15,9 @@ class CFX_BinaryBuf;
 typedef int FX_STRSIZE;
 class CFX_ByteStringL;
 class CFX_WideStringL;
+
+// An immutable string with caller-provided storage which must outlive the
+// string itself.
 class CFX_ByteStringC : public CFX_Object
 {
 public:
@@ -38,6 +41,13 @@ public:
         m_Length = ptr ? (FX_STRSIZE)FXSYS_strlen(ptr) : 0;
     }
 
+    // |ch| must be an lvalue that outlives the the CFX_ByteStringC. However,
+    // the use of char rvalues are not caught at compile time.  They are
+    // implicitly promoted to CFX_ByteString (see below) and then the
+    // CFX_ByteStringC is constructed from the CFX_ByteString via the alternate
+    // constructor below. The CFX_ByteString then typically goes out of scope
+    // and |m_Ptr| may be left pointing to invalid memory. Beware.
+    // TODO(tsepez): Mark single-argument string constructors as explicit.
     CFX_ByteStringC(FX_CHAR& ch)
     {
         m_Ptr = (FX_LPCBYTE)&ch;
@@ -65,7 +75,7 @@ public:
     CFX_ByteStringC& operator = (FX_LPCSTR src)
     {
         m_Ptr = (FX_LPCBYTE)src;
-        m_Length = (FX_STRSIZE)FXSYS_strlen(src);
+        m_Length = m_Ptr ? (FX_STRSIZE)FXSYS_strlen(src) : 0;
         return *this;
     }
 
diff --git a/core/src/fxcrt/fx_basic_bstring.cpp b/core/src/fxcrt/fx_basic_bstring.cpp
index c54148d799..0d4f860b32 100644
--- a/core/src/fxcrt/fx_basic_bstring.cpp
+++ b/core/src/fxcrt/fx_basic_bstring.cpp
@@ -1082,7 +1082,7 @@ FX_DWORD CFX_ByteStringC::GetID(FX_STRSIZE start_pos) const
     if (m_Length == 0) {
         return 0;
     }
-    if (start_pos >= m_Length) {
+    if (start_pos < 0 || start_pos >= m_Length) {
         return 0;
     }
     FX_DWORD strid = 0;
diff --git a/core/src/fxcrt/fx_basic_bstring_unittest.cpp b/core/src/fxcrt/fx_basic_bstring_unittest.cpp
index 138f1bff2c..030b6aea10 100644
--- a/core/src/fxcrt/fx_basic_bstring_unittest.cpp
+++ b/core/src/fxcrt/fx_basic_bstring_unittest.cpp
@@ -13,30 +13,180 @@ TEST(fxcrt, ByteStringCNull) {
   EXPECT_TRUE(null_string.IsEmpty());
 
   CFX_ByteStringC another_null_string;
-  EXPECT_TRUE(null_string == another_null_string);
+  EXPECT_EQ(null_string, another_null_string);
 
-  CFX_ByteString copied_null_string(null_string);
-  EXPECT_EQ(null_string.GetPtr(), nullptr);
-  EXPECT_EQ(null_string.GetLength(), 0);
-  EXPECT_TRUE(null_string.IsEmpty());
-  EXPECT_TRUE(null_string == another_null_string);
+  CFX_ByteStringC copied_null_string(null_string);
+  EXPECT_EQ(copied_null_string.GetPtr(), nullptr);
+  EXPECT_EQ(copied_null_string.GetLength(), 0);
+  EXPECT_TRUE(copied_null_string.IsEmpty());
+  EXPECT_EQ(null_string, copied_null_string);
 
-  CFX_ByteStringC empty_string("");
-  EXPECT_EQ(null_string.GetPtr(), nullptr);
-  EXPECT_EQ(null_string.GetLength(), 0);
-  EXPECT_TRUE(null_string.IsEmpty());
-  EXPECT_TRUE(null_string == empty_string);
+  CFX_ByteStringC empty_string("");  // Pointer to NUL, not NULL pointer.
+  EXPECT_NE(empty_string.GetPtr(), nullptr);
+  EXPECT_EQ(empty_string.GetLength(), 0);
+  EXPECT_TRUE(empty_string.IsEmpty());
+  EXPECT_EQ(null_string, empty_string);
+
+  CFX_ByteStringC assigned_null_string("initially not NULL");
+  assigned_null_string = null_string;
+  EXPECT_EQ(assigned_null_string.GetPtr(), nullptr);
+  EXPECT_EQ(assigned_null_string.GetLength(), 0);
+  EXPECT_TRUE(assigned_null_string.IsEmpty());
+  EXPECT_EQ(null_string, assigned_null_string);
+
+  CFX_ByteStringC assigned_nullptr_string("initially not NULL");
+  assigned_nullptr_string = (FX_LPCSTR)nullptr;
+  EXPECT_EQ(assigned_nullptr_string.GetPtr(), nullptr);
+  EXPECT_EQ(assigned_nullptr_string.GetLength(), 0);
+  EXPECT_TRUE(assigned_nullptr_string.IsEmpty());
+  EXPECT_EQ(null_string, assigned_nullptr_string);
 
   CFX_ByteStringC non_null_string("a");
-  EXPECT_FALSE(null_string == non_null_string);
+  EXPECT_NE(null_string, non_null_string);
+}
+
+TEST(fxcrt, ByteStringCNotNull) {
+  CFX_ByteStringC string3("abc");
+  CFX_ByteStringC string6("abcdef");
+  CFX_ByteStringC alternate_string3("abcdef", 3);
+  CFX_ByteStringC embedded_nul_string7("abc\0def", 7);
+  CFX_ByteStringC illegal_string7("abcdef", 7);
+
+  EXPECT_EQ(3, string3.GetLength());
+  EXPECT_EQ(6, string6.GetLength());
+  EXPECT_EQ(3, alternate_string3.GetLength());
+  EXPECT_EQ(7, embedded_nul_string7.GetLength());
+  EXPECT_EQ(7, illegal_string7.GetLength());
+
+  EXPECT_NE(string3, string6);
+  EXPECT_EQ(string3, alternate_string3);
+  EXPECT_NE(string3, embedded_nul_string7);
+  EXPECT_NE(string3, illegal_string7);
+  EXPECT_NE(string6, alternate_string3);
+  EXPECT_NE(string6, embedded_nul_string7);
+  EXPECT_NE(string6, illegal_string7);
+  EXPECT_NE(alternate_string3, embedded_nul_string7);
+  EXPECT_NE(alternate_string3, illegal_string7);
+  EXPECT_NE(embedded_nul_string7, illegal_string7);
+
+  CFX_ByteStringC copied_string3(string3);
+  CFX_ByteStringC copied_alternate_string3(alternate_string3);
+  CFX_ByteStringC copied_embedded_nul_string7(embedded_nul_string7);
+
+  EXPECT_EQ(string3, copied_string3);
+  EXPECT_EQ(alternate_string3, copied_alternate_string3);
+  EXPECT_EQ(embedded_nul_string7, copied_embedded_nul_string7);
+
+  CFX_ByteStringC assigned_string3("intially something else");
+  CFX_ByteStringC assigned_alternate_string3("initally something else");
+  CFX_ByteStringC assigned_ptr_string3("initially something else");
+  CFX_ByteStringC assigned_embedded_nul_string7("initially something else");
+
+  assigned_string3 = string3;
+  assigned_alternate_string3 = alternate_string3;
+  assigned_ptr_string3 = "abc";
+  assigned_embedded_nul_string7 = embedded_nul_string7;
+  EXPECT_EQ(string3, assigned_string3);
+  EXPECT_EQ(alternate_string3, assigned_alternate_string3);
+  EXPECT_EQ(alternate_string3, assigned_ptr_string3);
+  EXPECT_EQ(embedded_nul_string7, assigned_embedded_nul_string7);
+}
+
+TEST(fxcrt, ByteStringCFromChar) {
+  CFX_ByteStringC null_string;
+  CFX_ByteStringC lower_a_string("a");
+
+  // Must have lvalues that outlive the corresponding ByteStringC.
+  char nul = '\0';
+  char lower_a = 'a';
+  CFX_ByteStringC nul_string_from_char(nul);
+  CFX_ByteStringC lower_a_string_from_char(lower_a);
+
+  // Pointer to nul, not NULL ptr, hence length 1 ...
+  EXPECT_EQ(1, nul_string_from_char.GetLength());
+  EXPECT_NE(null_string, nul_string_from_char);
 
-  // TODO(tsepez): fix assignment of a null ptr to a CFX_ByteStringC.
+  EXPECT_EQ(1, lower_a_string_from_char.GetLength());
+  EXPECT_EQ(lower_a_string, lower_a_string_from_char);
+  EXPECT_NE(nul_string_from_char, lower_a_string_from_char);
+
+  CFX_ByteStringC longer_string("ab");
+  EXPECT_NE(longer_string, lower_a_string_from_char);
 }
 
 TEST(fxcrt, ByteStringCGetID) {
   CFX_ByteStringC null_string;
-  EXPECT_EQ(null_string.GetID(), 0u);
+  EXPECT_EQ(0u, null_string.GetID());
+  EXPECT_EQ(0u, null_string.GetID(1));
+  EXPECT_EQ(0u, null_string.GetID(-1));
+  EXPECT_EQ(0u, null_string.GetID(-1000000));
 
   CFX_ByteStringC empty_string("");
-  EXPECT_EQ(empty_string.GetID(), 0u);
+  EXPECT_EQ(0u, empty_string.GetID());
+  EXPECT_EQ(0u, empty_string.GetID(1));
+  EXPECT_EQ(0u, empty_string.GetID(-1));
+  EXPECT_EQ(0u, empty_string.GetID(-1000000));
+
+  CFX_ByteStringC short_string("ab");
+  EXPECT_EQ(FXBSTR_ID('a', 'b', 0, 0), short_string.GetID());
+  EXPECT_EQ(FXBSTR_ID('b', 0, 0, 0), short_string.GetID(1));
+  EXPECT_EQ(0u, short_string.GetID(2));
+  EXPECT_EQ(0u, short_string.GetID(-1));
+  EXPECT_EQ(0u, short_string.GetID(-1000000));
+
+  CFX_ByteStringC longer_string("abcdef");
+  EXPECT_EQ(FXBSTR_ID('a', 'b', 'c', 'd'), longer_string.GetID());
+  EXPECT_EQ(FXBSTR_ID('b', 'c', 'd', 'e'), longer_string.GetID(1));
+  EXPECT_EQ(FXBSTR_ID('c', 'd', 'e', 'f'), longer_string.GetID(2));
+  EXPECT_EQ(FXBSTR_ID('d', 'e', 'f', 0), longer_string.GetID(3));
+  EXPECT_EQ(FXBSTR_ID('e', 'f', 0 , 0), longer_string.GetID(4));
+  EXPECT_EQ(FXBSTR_ID('f', 0 , 0, 0), longer_string.GetID(5));
+  EXPECT_EQ(0u, longer_string.GetID(6));
+  EXPECT_EQ(0u, longer_string.GetID(-1));
+  EXPECT_EQ(0u, longer_string.GetID(-1000000));
+}
+
+TEST(fxcrt, ByteStringCMid) {
+  CFX_ByteStringC null_string;
+  EXPECT_EQ(null_string, null_string.Mid(0, 1));
+  EXPECT_EQ(null_string, null_string.Mid(1, 1));
+
+  CFX_ByteStringC empty_string("");
+  EXPECT_EQ(empty_string, empty_string.Mid(0, 1));
+  EXPECT_EQ(empty_string, empty_string.Mid(1, 1));
+
+  CFX_ByteStringC single_character("a");
+  EXPECT_EQ(empty_string, single_character.Mid(0, 0));
+  EXPECT_EQ(single_character, single_character.Mid(0, 1));
+  EXPECT_EQ(empty_string, single_character.Mid(1, 0));
+  EXPECT_EQ(empty_string, single_character.Mid(1, 1));
+
+  CFX_ByteStringC longer_string("abcdef");
+  EXPECT_EQ(longer_string, longer_string.Mid(0, 6));
+  EXPECT_EQ(longer_string, longer_string.Mid(0, 187));
+  EXPECT_EQ(longer_string, longer_string.Mid(-42, 6));
+  EXPECT_EQ(longer_string, longer_string.Mid(-42, 187));
+
+  CFX_ByteStringC leading_substring("ab");
+  EXPECT_EQ(leading_substring, longer_string.Mid(0, 2));
+  EXPECT_EQ(leading_substring, longer_string.Mid(-1, 2));
+
+  CFX_ByteStringC middle_substring("bcde");
+  EXPECT_EQ(middle_substring, longer_string.Mid(1, 4));
+
+  CFX_ByteStringC trailing_substring("ef");
+  EXPECT_EQ(trailing_substring, longer_string.Mid(4, 2));
+  EXPECT_EQ(trailing_substring, longer_string.Mid(4, 3));
+}
+
+TEST(fxcrt, ByteStringCGetAt) {
+  CFX_ByteString short_string("a");
+  CFX_ByteString longer_string("abc");
+  CFX_ByteString embedded_nul_string("ab\0c", 4);
+
+  EXPECT_EQ('a', short_string.GetAt(0));
+  EXPECT_EQ('c', longer_string.GetAt(2));
+  EXPECT_EQ('b', embedded_nul_string.GetAt(1));
+  EXPECT_EQ('\0', embedded_nul_string.GetAt(2));
+  EXPECT_EQ('c', embedded_nul_string.GetAt(3));
 }