kernel32/tests: Add more ExpandEnvironmentStringsA() tests.

Document the observed ExpandEnvironmentStrings() behavior.

dlls/kernel32/environ.c

@@ -305,6 +305,8 @@ BOOL WINAPI SetEnvironmentVariableW( LPCWSTR name, LPCWSTR value )
 /***********************************************************************
  *           ExpandEnvironmentStringsA   (KERNEL32.@)
  *
+ * See ExpandEnvironmentStringsW.
+ *
  * Note: overlapping buffers are not supported; this is how it should be.
  * FIXME: return value is wrong for MBCS
  */
@@ -334,6 +336,21 @@ DWORD WINAPI ExpandEnvironmentStringsA( LPCSTR src, LPSTR dst, DWORD count )
 
 /***********************************************************************
  *           ExpandEnvironmentStringsW   (KERNEL32.@)
+ *
+ * Replaces references to environment variables of the form '%EnvVar%'
+ * by their value. If the environment variable does not exist, then the
+ * reference is left as is.
+ *
+ * PARAMS
+ *  src       [I] The string to be expanded.
+ *  dst       [O] The buffer in which to put the expanded string.
+ *  len       [I] The buffer size, in characters.
+ *
+ * RETURNS
+ *  The number of characters copied into the buffer. If the buffer is
+ *  too small, then the required buffer size, in characters including the
+ *  trailing '\0', is returned.
+ *  If the function fails for some other reason, then it returns 0.
  */
 DWORD WINAPI ExpandEnvironmentStringsW( LPCWSTR src, LPWSTR dst, DWORD len )
 {
@@ -346,7 +363,7 @@ DWORD WINAPI ExpandEnvironmentStringsW( LPCWSTR src, LPWSTR dst, DWORD len )
 
     RtlInitUnicodeString(&us_src, src);
 
-    /* make sure we don't overflow maximum UNICODE_STRING size */
+    /* make sure we don't overflow the maximum UNICODE_STRING size */
     if (len > 0x7fff)
         len = 0x7fff;
 

dlls/kernel32/tests/environ.c

@@ -217,9 +217,55 @@ static void test_GetSetEnvironmentVariableW(void)
 
 static void test_ExpandEnvironmentStringsA(void)
 {
+    const char* value="Long long value";
+    const char* not_an_env_var="%NotAnEnvVar%";
     char buf[256], buf1[256], buf2[0x8000];
     DWORD ret_size, ret_size1;
 
+    SetEnvironmentVariableA("EnvVar", value);
+
+    ret_size = ExpandEnvironmentStringsA(NULL, buf1, sizeof(buf1));
+    ok(ret_size == 1 || ret_size == 0 /* Win9x */,
+       "ExpandEnvironmentStrings returned %d\n", ret_size);
+
+    /* Try to get the required buffer size 'the natural way' */
+    strcpy(buf, "%EnvVar%");
+    ret_size = ExpandEnvironmentStringsA(buf, NULL, 0);
+    /* v5.1.2600.2945 (XP SP2) returns len + 2 here! */
+    ok(ret_size == strlen(value)+1 || ret_size == strlen(value)+2 || ret_size == 0 /* Win95 */,
+       "ExpandEnvironmentStrings returned %d instead of %d\n",
+       ret_size, strlen(value)+1);
+    if (ret_size == strlen(value)+2)
+        trace("ExpandEnvironmentStrings is buggy: it returned len + 2\n");
+
+    /* Again, side-stepping the Win95 bug */
+    ret_size = ExpandEnvironmentStringsA(buf, buf1, 0);
+    /* v5.1.2600.2945 (XP SP2) returns len + 2 here! */
+    ok(ret_size == strlen(value)+1 || ret_size == strlen(value)+2,
+       "ExpandEnvironmentStrings returned %d instead of %d\n",
+       ret_size, strlen(value)+1);
+
+    /* Try with a buffer that's too small */
+    ret_size = ExpandEnvironmentStringsA(buf, buf1, 12);
+    /* v5.1.2600.2945 (XP SP2) returns len + 2 here! */
+    ok(ret_size == strlen(value)+1 || ret_size == strlen(value)+2,
+       "ExpandEnvironmentStrings returned %d instead of %d\n",
+       ret_size, strlen(value)+1);
+
+    /* Try with a buffer of just the right size */
+    /* v5.1.2600.2945 (XP SP2) needs and returns len + 2 here! */
+    ret_size = ExpandEnvironmentStringsA(buf, buf1, ret_size);
+    ok(ret_size == strlen(value)+1 || ret_size == strlen(value)+2,
+       "ExpandEnvironmentStrings returned %d instead of %d\n",
+       ret_size, strlen(value)+1);
+    ok(!strcmp(buf1, value), "ExpandEnvironmentStrings returned [%s]\n", buf1);
+
+    /* Try with an unset environment variable */
+    strcpy(buf, not_an_env_var);
+    ret_size = ExpandEnvironmentStringsA(buf, buf1, sizeof(buf1));
+    ok(ret_size == strlen(not_an_env_var)+1, "ExpandEnvironmentStrings returned %d instead of %d\n", ret_size, strlen(value)+1);
+    ok(!strcmp(buf1, not_an_env_var), "ExpandEnvironmentStrings returned [%s]\n", buf1);
+
     /* test a large destination size */
     strcpy(buf, "12345");
     ret_size = ExpandEnvironmentStringsA(buf, buf2, sizeof(buf2));
@@ -231,6 +277,8 @@ static void test_ExpandEnvironmentStringsA(void)
     if (ERROR_ENVVAR_NOT_FOUND == GetLastError())
         return;
     ok(!strcmp(buf, buf1), "ExpandEnvironmentStrings failed %s vs %s. ret_size = %d\n", buf, buf1, ret_size);
+
+    SetEnvironmentVariableA("EnvVar", NULL);
 }
 
 static BOOL (WINAPI *pGetComputerNameExA)(COMPUTER_NAME_FORMAT,LPSTR,LPDWORD);