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  • Is assert evil?

    - by dehmann
    The Go language creators write: Go doesn't provide assertions. (...) Programmers use them as a crutch to avoid thinking about proper error handling and reporting. What is your opinion about this?

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  • Visual Studio 2008 “Format Document/Selection” command and a function named “assert” in JavaScript c

    - by AGS777
    Just have found some funny behavior of the Visual Studio 2008 editor.  Sorry if it is already well known bug. If you happened to have a JavaScript function named “assert” in your code (and there is pretty high likelihood in my opinion), for example something like: function assert(x, message) { if (x) console.log(message); } then when either Format Document (Ctrl + K, Ctrl + D) or Format Selection (Ctrl + K, Ctrl + F) command is applied to the document/block containing the function, the result of the formatting will be: functionassert(x, message) { if (x) console.log(message); } That’s it. function and assert are now joined into one solid word. So be aware of the fact in case you suddenly start receiving  strange exception in your JavaScript code: missing ; before statement functionassert(x, message) And no, it is not an April Fool's joke. Just try for yourself.

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  • junit assert in thread throws exception

    - by antony.trupe
    What am I doing wrong that an exception is thrown instead of showing a failure, or should I not have assertions inside threads? @Test public void testComplex() throws InterruptedException { int loops = 10; for (int i = 0; i < loops; i++) { final int j = i; new Thread() { @Override public void run() { ApiProxy.setEnvironmentForCurrentThread(env);//ignore this new CounterFactory().getCounter("test").increment();//ignore this too int count2 = new CounterFactory().getCounter("test").getCount();//ignore assertEquals(j, count2);//here be exceptions thrown. this is line 75 } }.start(); } Thread.sleep(5 * 1000); assertEquals(loops, new CounterFactory().getCounter("test").getCount()); } StackTrace Exception in thread "Thread-26" junit.framework.AssertionFailedError: expected:<5> but was:<6> at junit.framework.Assert.fail(Assert.java:47) at junit.framework.Assert.failNotEquals(Assert.java:277) at junit.framework.Assert.assertEquals(Assert.java:64) at junit.framework.Assert.assertEquals(Assert.java:195) at junit.framework.Assert.assertEquals(Assert.java:201) at com.bitdual.server.dao.ShardedCounterTest$3.run(ShardedCounterTest.java:77)

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  • How to properly rewrite ASSERT code to pass /analyze in msvc?

    - by Sorin Sbarnea
    Visual Studio added code analysis (/analyze) for C/C++ in order to help identify bad code. This is quite a nice feature but when you deal with and old project you may be overwhelmed by the number of warnings. Most of the problems are generating because the old code is doing some ASSERT at the beginning of the method or function. I think this is the ASSERT definition used in the code (from afx.h) #define ASSERT(f) DEBUG_ONLY((void) ((f) || !::AfxAssertFailedLine(THIS_FILE, __LINE__) || (AfxDebugBreak(), 0))) Example code: ASSERT(pBytes != NULL); *pBytes = 0; // <- warning C6011: Dereferencing NULL pointer 'pBytes' I'm looking for an easy and safe solution to solve these warnings that does not imply disabling these warnings. Did I mention that there are lots of occurrences in current codebase?

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  • Can someone help me with this Java Chess game please?

    - by Chris Edwards
    Hey guys, Please can someone have a look at this code and let me know whether I am on the right track with the "check_somefigure_move"s and the "check_black/white_promotion"s please? And also any other help you can give would be greatly appreciated! Thanks! P.S. I know the code is not the best implementation, but its a template I have to follow :( Code: class Moves { private final Board B; private boolean regular; public Moves(final Board b) { B = b; regular = regular_position(); } public boolean get_regular_position() { return regular; } public void set_regular_position(final boolean new_reg) { regular = new_reg; } // checking whether B represents a "normal" position or not; // if not, then only simple checks regarding move-correctness should // be performed, only checking the direct characteristics of the figure // moved; // checks whether there is exactly one king of each colour, there are // no more figures than promotions allow, and there are no pawns on the // first or last rank; public boolean regular_position() { int[] counts = new int[256]; for (char file = 'a'; file <= 'h'; ++file) for (char rank = '1'; rank <= '8'; ++rank) ++counts[(int) B.get(file,rank)]; if (counts[Board.white_king] != 1 || counts[Board.black_king] != 1) return false; if (counts[Board.white_pawn] > 8 || counts[Board.black_pawn] > 8) return false; int count_w_promotions = 0; count_w_promotions += Math.max(counts[Board.white_queen]-1,0); count_w_promotions += Math.max(counts[Board.white_rook]-2,0); count_w_promotions += Math.max(counts[Board.white_bishop]-2,0); count_w_promotions += Math.max(counts[Board.white_knight]-2,0); if (count_w_promotions > 8 - counts[Board.white_pawn]) return false; int count_b_promotions = 0; count_b_promotions += Math.max(counts[Board.black_queen]-1,0); count_b_promotions += Math.max(counts[Board.black_rook]-2,0); count_b_promotions += Math.max(counts[Board.black_bishop]-2,0); count_b_promotions += Math.max(counts[Board.black_knight]-2,0); if (count_b_promotions > 8 - counts[Board.black_pawn]) return false; for (char file = 'a'; file <= 'h'; ++file) { final char fig1 = B.get(file,'1'); if (fig1 == Board.white_pawn || fig1 == Board.black_pawn) return false; final char fig8 = B.get(file,'8'); if (fig8 == Board.white_pawn || fig8 == Board.black_pawn) return false; } return true; } public boolean check_normal_white_move(final char file0, final char rank0, final char file1, final char rank1) { if (! Board.is_valid_white_figure(B.get(file0,rank0))) return false; if (! B.is_empty(file1,rank1) && ! Board.is_valid_black_figure(B.get(file1,rank1))) return false; if (B.get_active_colour() != 'w') return false; if (! check_move_simple(file0,rank0,file1,rank1)) return false; if (! regular) return true; final Board test_board = new Board(B); test_board.normal_white_move_0(file0,rank0,file1,rank1); final Moves test_move = new Moves(test_board); final char[] king_pos = test_move.white_king_position(); assert(king_pos.length == 2); return test_move.black_not_attacking(king_pos[0],king_pos[1]); } public boolean check_normal_black_move(final char file0, final char rank0, final char file1, final char rank1) { // ADDED THE CHECK NORMAL BLACK MOVE BASED ON THE CHECK NORMAL WHITE MOVE if (! Board.is_valid_black_figure(B.get(file0,rank0))) return false; if (! B.is_empty(file1,rank1) && ! Board.is_valid_white_figure(B.get(file1,rank1))) return false; if (B.get_active_colour() != 'b') return false; if (! check_move_simple(file0,rank0,file1,rank1)) return false; if (! regular) return true; final Board test_board = new Board(B); test_board.normal_black_move_0(file0,rank0,file1,rank1); final Moves test_move = new Moves(test_board); final char[] king_pos = test_move.black_king_position(); assert(king_pos.length == 2); return test_move.white_not_attacking(king_pos[0],king_pos[1]); } // for checking a normal move by just applying the move-rules private boolean check_move_simple(final char file0, final char rank0, final char file1, final char rank1) { final char fig = B.get(file0,rank0); if (fig == Board.white_king || fig == Board.black_king) return check_king_move(file0,rank0,file1,rank1); if (fig == Board.white_queen || fig == Board.black_queen) return check_queen_move(file0,rank0,file1,rank1); if (fig == Board.white_rook || fig == Board.black_rook) return check_rook_move(file0,rank0,file1,rank1); if (fig == Board.white_bishop || fig == Board.black_bishop) return check_bishop_move(file0,rank0,file1,rank1); if (fig == Board.white_knight || fig == Board.black_knight) return check_knight_move(file0,rank0,file1,rank1); if (fig == Board.white_pawn) return check_white_pawn_move(file0,rank0,file1,rank1); else return check_black_pawn_move(file0,rank0,file1,rank1); } private boolean check_king_move(final char file0, final char rank0, final char file1, final char rank1) { // ADDED KING MOVE int fileChange = file0 - file1; int rankChange = rank0 - rank1; return fileChange <= 1 && fileChange >= -1 && rankChange <= 1 && rankChange >= -1; } private boolean check_queen_move(final char file0, final char rank0, final char file1, final char rank1) { // ADDED QUEEN MOVE int fileChange = file0 - file1; int rankChange = rank0 - rank1; return fileChange <=8 && fileChange >= -8 && rankChange <= 8 && rankChange >= -8; } private boolean check_rook_move(final char file0, final char rank0, final char file1, final char rank1) { // ADDED ROOK MOVE int fileChange = file0 - file1; int rankChange = rank0 - rank1; return fileChange <=8 || fileChange >= -8 || rankChange <= 8 || rankChange >= -8; } private boolean check_bishop_move(final char file0, final char rank0, final char file1, final char rank1) { // ADDED BISHOP MOVE int fileChange = file0 - file1; int rankChange = rank0 - rank1; return fileChange <= 8 && rankChange <= 8 || fileChange <= 8 && rankChange >= -8 || fileChange >= -8 && rankChange >= -8 || fileChange >= -8 && rankChange <= 8; } private boolean check_knight_move(final char file0, final char rank0, final char file1, final char rank1) { // ADDED KNIGHT MOVE int fileChange = file0 - file1; int rankChange = rank0 - rank1; /* IS THIS THE CORRECT WAY? * return fileChange <= 1 && rankChange <= 2 || fileChange <= 1 && rankChange >= -2 || fileChange <= 2 && rankChange <= 1 || fileChange <= 2 && rankChange >= -1 || fileChange >= -1 && rankChange <= 2 || fileChange >= -1 && rankChange >= -2 || fileChange >= -2 && rankChange <= 1 || fileChange >= -2 && rankChange >= -1;*/ // OR IS THIS? return fileChange <= 1 || fileChange >= -1 || fileChange <= 2 || fileChange >= -2 && rankChange <= 1 || rankChange >= - 1 || rankChange <= 2 || rankChange >= -2; } private boolean check_white_pawn_move(final char file0, final char rank0, final char file1, final char rank1) { // ADDED PAWN MOVE int fileChange = file0 - file1; int rankChange = rank0 - rank1; return fileChange == 0 && rankChange <= 1; } private boolean check_black_pawn_move(final char file0, final char rank0, final char file1, final char rank1) { // ADDED PAWN MOVE int fileChange = file0 - file1; int rankChange = rank0 - rank1; return fileChange == 0 && rankChange >= -1; } public boolean check_white_kingside_castling() { // only demonstration code: final char c = B.get_white_castling(); if (c == '-' || c == 'q') return false; if (B.get_active_colour() == 'b') return false; if (B.get('e','1') != 'K') return false; if (! black_not_attacking('e','1')) return false; if (! free_white('f','1')) return false; // XXX return true; } public boolean check_white_queenside_castling() { // only demonstration code: final char c = B.get_white_castling(); if (c == '-' || c == 'k') return false; if (B.get_active_colour() == 'b') return false; // ADDED BASED ON KINGSIDE CASTLING if (B.get('e','1') != 'Q') return false; if (! black_not_attacking('e','1')) return false; if (! free_white('f','1')) return false; // XXX return true; } public boolean check_black_kingside_castling() { // only demonstration code: final char c = B.get_black_castling(); if (c == '-' || c == 'q') return false; if (B.get_active_colour() == 'w') return false; // ADDED BASED ON CHECK WHITE if (B.get('e','8') != 'K') return false; if (! black_not_attacking('e','8')) return false; if (! free_white('f','8')) return false; // XXX return true; } public boolean check_black_queenside_castling() { // only demonstration code: final char c = B.get_black_castling(); if (c == '-' || c == 'k') return false; if (B.get_active_colour() == 'w') return false; // ADDED BASED ON KINGSIDE CASTLING if (B.get('e','8') != 'Q') return false; if (! black_not_attacking('e','8')) return false; if (! free_white('f','8')) return false; // XXX return true; } public boolean check_white_promotion(final char pawn_file, final char figure) { // XXX // ADDED CHECKING FOR CORRECT FIGURE AND POSITION - ALTHOUGH IT SEEMS AS THOUGH // PAWN_FILE SHOULD BE PAWN_RANK, AS IT IS THE REACHING OF THE END RANK THAT // CAUSES PROMOTION OF A PAWN, NOT FILE if (figure == P && pawn_file == 8) { return true; } else return false; } public boolean check_black_promotion(final char pawn_file, final char figure) { // XXX // ADDED CHECKING FOR CORRECT FIGURE AND POSITION if (figure == p && pawn_file == 1) { return true; } else return false; } // checks whether black doesn't attack the field: public boolean black_not_attacking(final char file, final char rank) { // XXX return true; } public boolean free_white(final char file, final char rank) { // XXX return black_not_attacking(file,rank) && B.is_empty(file,rank); } // checks whether white doesn't attack the field: public boolean white_not_attacking(final char file, final char rank) { // XXX return true; } public boolean free_black(final char file, final char rank) { // XXX return white_not_attacking(file,rank) && B.is_empty(file,rank); } public char[] white_king_position() { for (char file = 'a'; file <= 'h'; ++file) for (char rank = '1'; rank <= '8'; ++rank) if (B.get(file,rank) == Board.white_king) { char[] result = new char[2]; result[0] = file; result[1] = rank; return result; } return new char[0]; } public char[] black_king_position() { for (char file = 'a'; file <= 'h'; ++file) for (char rank = '1'; rank <= '8'; ++rank) if (B.get(file,rank) == Board.black_king) { char[] result = new char[2]; result[0] = file; result[1] = rank; return result; } return new char[0]; } public static void main(final String[] args) { // checking regular_position { Moves m = new Moves(new Board()); assert(m.regular_position()); m = new Moves(new Board("8/8/8/8/8/8/8/8 w - - 0 1")); assert(!m.regular_position()); m = new Moves(new Board("KK6/8/8/8/8/8/8/8 w - - 0 1")); assert(!m.regular_position()); m = new Moves(new Board("kk6/8/8/8/8/8/8/8 w - - 0 1")); assert(!m.regular_position()); m = new Moves(new Board("Kk6/8/8/8/8/8/8/8 w - - 0 1")); assert(m.regular_position()); m = new Moves(new Board("Kk6/qqqqqqqq/QQQQQQQQ/Q7/q7/rrbbnn2/RRBBNN2/8 w - - 0 1")); assert(m.regular_position()); m = new Moves(new Board("Kk6/qqqqqqqq/QQQQQQQQ/Q7/q7/rrbbnn2/RRBBNN2/n7 w - - 0 1")); assert(!m.regular_position()); m = new Moves(new Board("Kk6/qqqqqqqq/QQQQQQQQ/Q7/q7/rrbbnn2/RRBBNN2/N7 w - - 0 1")); m = new Moves(new Board("Kk6/qqqqqqqq/QQQQQQQQ/Q7/q7/rrbbnn2/RRBBNN2/b7 w - - 0 1")); assert(!m.regular_position()); m = new Moves(new Board("Kk6/qqqqqqqq/QQQQQQQQ/Q7/q7/rrbbnn2/RRBBNN2/B7 w - - 0 1")); m = new Moves(new Board("Kk6/qqqqqqqq/QQQQQQQQ/Q7/q7/rrbbnn2/RRBBNN2/r7 w - - 0 1")); assert(!m.regular_position()); m = new Moves(new Board("Kk6/qqqqqqqq/QQQQQQQQ/Q7/q7/rrbbnn2/RRBBNN2/R7 w - - 0 1")); m = new Moves(new Board("Kk6/qqqqqqqq/QQQQQQQQ/Q7/q7/rrbbnn2/RRBBNN2/q7 w - - 0 1")); assert(!m.regular_position()); m = new Moves(new Board("Kk6/qqqqqqqq/QQQQQQQQ/Q7/q7/rrbbnn2/RRBBNN2/Q7 w - - 0 1")); assert(!m.regular_position()); m = new Moves(new Board("Kkp5/8/8/8/8/8/8/8 w - - 0 1")); assert(!m.regular_position()); m = new Moves(new Board("KkP5/8/8/8/8/8/8/8 w - - 0 1")); assert(!m.regular_position()); m = new Moves(new Board("Kk6/8/8/8/8/8/8/7p w - - 0 1")); assert(!m.regular_position()); m = new Moves(new Board("Kk6/8/8/8/8/8/8/7P w - - 0 1")); assert(!m.regular_position()); } // checking check_white/black_king/queenside_castling { Moves m = new Moves(new Board("4k2r/8/8/8/8/8/8/4K2R w Kk - 0 1")); assert(!m.check_white_kingside_castling()); assert(!m.check_black_kingside_castling()); assert(!m.check_white_queenside_castling()); assert(!m.check_black_queenside_castling()); m = new Moves(new Board("4k2r/8/8/8/8/8/8/4K2R b Kk - 0 1")); assert(!m.check_white_kingside_castling()); assert(!m.check_black_kingside_castling()); assert(!m.check_white_queenside_castling()); assert(!m.check_black_queenside_castling()); m = new Moves(new Board("4k2r/4pppp/8/8/8/8/4PPPP/4K2R w KQkq - 0 1")); assert(m.check_white_kingside_castling()); assert(!m.check_black_kingside_castling()); assert(!m.check_white_queenside_castling()); assert(!m.check_black_queenside_castling()); m = new Moves(new Board("4k2r/4pppp/8/8/8/8/4PPPP/4K2R b KQkq - 0 1")); assert(!m.check_white_kingside_castling()); assert(m.check_black_kingside_castling()); assert(!m.check_white_queenside_castling()); assert(!m.check_black_queenside_castling()); m = new Moves(new Board("r3k3/8/8/8/8/8/8/R3K3 w Qq - 0 1")); assert(!m.check_white_kingside_castling()); assert(!m.check_black_kingside_castling()); assert(!m.check_white_queenside_castling()); assert(!m.check_black_queenside_castling()); m = new Moves(new Board("r3k3/8/8/8/8/8/8/R3K3 b Qq - 0 1")); assert(!m.check_white_kingside_castling()); assert(!m.check_black_kingside_castling()); assert(!m.check_white_queenside_castling()); assert(!m.check_black_queenside_castling()); m = new Moves(new Board("r3k3/p7/8/8/8/8/8/R3K3 w Qq - 0 1")); assert(!m.check_white_kingside_castling()); assert(!m.check_black_kingside_castling()); assert(m.check_white_queenside_castling()); assert(!m.check_black_queenside_castling()); m = new Moves(new Board("r3k3/p7/8/8/8/8/8/R3K3 b Qq - 0 1")); assert(!m.check_white_kingside_castling()); assert(!m.check_black_kingside_castling()); assert(!m.check_white_queenside_castling()); assert(m.check_black_queenside_castling()); m = new Moves(new Board("r3k3/p7/8/8/8/n7/8/R3K3 w Qq - 0 1")); assert(!m.check_white_kingside_castling()); assert(!m.check_black_kingside_castling()); assert(!m.check_white_queenside_castling()); assert(!m.check_black_queenside_castling()); m = new Moves(new Board("r3k3/p7/B7/8/8/8/8/R3K3 b Qq - 0 1")); assert(!m.check_white_kingside_castling()); assert(!m.check_black_kingside_castling()); assert(!m.check_white_queenside_castling()); assert(!m.check_black_queenside_castling()); // XXX } } }

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  • Showplan Operator of the week - Assert

    As part of his mission to explain the Query Optimiser in practical terms, Fabiano attempts the feat of describing, one week at a time, all the major Showplan Operators used by SQL Server's Query Optimiser to build the Query Plan. He starts with Assert

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  • Debug.Assert-s use the same error message. Should I promote it to a static variable?

    - by Hamish Grubijan
    I love Asserts and code readability but not code duplication, and in several places I use a Debug.Assert which checks for the same condition like so: Debug.Assert(kosherBaconList.SelectedIndex != -1, "An error message along the lines - you should not ever be able to click on edit button without selecting a kosher bacon first."); This is in response to an actual bug, although the actual list does not contain kosher bacon. Anyhow, I can think of two approaches: private static readonly mustSelectKosherBaconBeforeEditAssertMessage = "An error message along the lines - you should not ever be able to " + "click on edit button without selecting a something first."; ... Debug.Assert( kosherBaconList.SelectedIndex != -1, mustSelectKosherBaconBeforeEditAssertMessage) or: if (kosherBaconList.SelectedIndex == -1) { AssertMustSelectKosherBaconBeforeEdit(); } ... [Conditional("DEBUG")] private void AssertMustSelectKosherBaconBeforeEdit() { // Compiler will optimize away this variable. string errorMessage = "An error message along the lines - you should not ever be able to " + "click on edit button without selecting a something first."; Debug.Assert(false, errorMessage); } or is there a third way which sucks less than either one above? Please share. General helpful relevant tips are also welcome.

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  • NUnit.Framework.Assert.IsInstanceOfType() is obsolete

    - by Malice
    I'm currently reading the book Professional Enterprise .NET and I've noticed this warning in some of the example programs: 'NUnit.Framework.Assert.IsInstanceOfType(System.Type, object)' is obsolete Now I may have already answered my own question but, to fix this warning is it simply a case of replacing Assert.IsInstanceOfType() with Assert.IsInstanceOf()? For example this: Assert.IsInstanceOfType(typeof(ClassName), variableName); would become: Assert.IsInstanceOf(typeof(ClassName), variableName);

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  • How to prevent Debug.Assert(...) to show a modal dialog

    - by Martin
    I have a couple of libraries which use Debug.Assert(...). I think that the Debug.Assert(...) are fine and I still want them to execute, but I don't want them to block the execution of my application. Ideally, I would only like them to be logged somewhere. Given that I can't change the code of the libraries (and that I still want to compile in debug and run the assertion), how do I prevent Debug.Assert(...) to show a modal dialog? Thanks!

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  • Why do MSTests Assert.AreEqual(1.0, double.NaN, 0.0) pass?

    - by Egil Hansen
    Short question, why do Assert.AreEqual(1.0, double.NaN, 0.0) pass when Assert.AreEqual(1.0, double.NaN) do not? Is it an error in MSTest or am I missing something here? Best regards, Egil. Update: Should probably add, that the reason behind my question is, that I have a bunch of unit tests that unfortunately passed due to the result of some linear algebraic matrix operation being NaN or (+/-)Infinity. The unit tests are fine, but since Assert.AreEqual on doubles with a delta will pass when actual or/and expected are NaN or Infinity, I was left to believe that the code I was testing was correct.

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  • Is it possible to add "assert" as a keyword in Delphi?

    - by stanleyxu2005
    I write couple of "assert(...)" in code, to make sure that pre- and post-conditions should be satisfied. We can tell the Delphi compiler, whether to compile with assertions in a debug version and without assertions in a release version. I would like to know, if it is possible, to highlight "assert" like other Pascal keywords?

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  • Using Stub Objects

    - by user9154181
    Having told the long and winding tale of where stub objects came from and how we use them to build Solaris, I'd like to focus now on the the nuts and bolts of building and using them. The following new features were added to the Solaris link-editor (ld) to support the production and use of stub objects: -z stub This new command line option informs ld that it is to build a stub object rather than a normal object. In this mode, it accepts the same command line arguments as usual, but will quietly ignore any objects and sharable object dependencies. STUB_OBJECT Mapfile Directive In order to build a stub version of an object, its mapfile must specify the STUB_OBJECT directive. When producing a non-stub object, the presence of STUB_OBJECT causes the link-editor to perform extra validation to ensure that the stub and non-stub objects will be compatible. ASSERT Mapfile Directive All data symbols exported from the object must have an ASSERT symbol directive in the mapfile that declares them as data and supplies the size, binding, bss attributes, and symbol aliasing details. When building the stub objects, the information in these ASSERT directives is used to create the data symbols. When building the real object, these ASSERT directives will ensure that the real object matches the linking interface presented by the stub. Although ASSERT was added to the link-editor in order to support stub objects, they are a general purpose feature that can be used independently of stub objects. For instance you might choose to use an ASSERT directive if you have a symbol that must have a specific address in order for the object to operate properly and you want to automatically ensure that this will always be the case. The material presented here is derived from a document I originally wrote during the development effort, which had the dual goals of providing supplemental materials for the stub object PSARC case, and as a set of edits that were eventually applied to the Oracle Solaris Linker and Libraries Manual (LLM). The Solaris 11 LLM contains this information in a more polished form. Stub Objects A stub object is a shared object, built entirely from mapfiles, that supplies the same linking interface as the real object, while containing no code or data. Stub objects cannot be used at runtime. However, an application can be built against a stub object, where the stub object provides the real object name to be used at runtime, and then use the real object at runtime. When building a stub object, the link-editor ignores any object or library files specified on the command line, and these files need not exist in order to build a stub. Since the compilation step can be omitted, and because the link-editor has relatively little work to do, stub objects can be built very quickly. Stub objects can be used to solve a variety of build problems: Speed Modern machines, using a version of make with the ability to parallelize operations, are capable of compiling and linking many objects simultaneously, and doing so offers significant speedups. However, it is typical that a given object will depend on other objects, and that there will be a core set of objects that nearly everything else depends on. It is necessary to impose an ordering that builds each object before any other object that requires it. This ordering creates bottlenecks that reduce the amount of parallelization that is possible and limits the overall speed at which the code can be built. Complexity/Correctness In a large body of code, there can be a large number of dependencies between the various objects. The makefiles or other build descriptions for these objects can become very complex and difficult to understand or maintain. The dependencies can change as the system evolves. This can cause a given set of makefiles to become slightly incorrect over time, leading to race conditions and mysterious rare build failures. Dependency Cycles It might be desirable to organize code as cooperating shared objects, each of which draw on the resources provided by the other. Such cycles cannot be supported in an environment where objects must be built before the objects that use them, even though the runtime linker is fully capable of loading and using such objects if they could be built. Stub shared objects offer an alternative method for building code that sidesteps the above issues. Stub objects can be quickly built for all the shared objects produced by the build. Then, all the real shared objects and executables can be built in parallel, in any order, using the stub objects to stand in for the real objects at link-time. Afterwards, the executables and real shared objects are kept, and the stub shared objects are discarded. Stub objects are built from a mapfile, which must satisfy the following requirements. The mapfile must specify the STUB_OBJECT directive. This directive informs the link-editor that the object can be built as a stub object, and as such causes the link-editor to perform validation and sanity checking intended to guarantee that an object and its stub will always provide identical linking interfaces. All function and data symbols that make up the external interface to the object must be explicitly listed in the mapfile. The mapfile must use symbol scope reduction ('*'), to remove any symbols not explicitly listed from the external interface. All global data exported from the object must have an ASSERT symbol attribute in the mapfile to specify the symbol type, size, and bss attributes. In the case where there are multiple symbols that reference the same data, the ASSERT for one of these symbols must specify the TYPE and SIZE attributes, while the others must use the ALIAS attribute to reference this primary symbol. Given such a mapfile, the stub and real versions of the shared object can be built using the same command line for each, adding the '-z stub' option to the link for the stub object, and omiting the option from the link for the real object. To demonstrate these ideas, the following code implements a shared object named idx5, which exports data from a 5 element array of integers, with each element initialized to contain its zero-based array index. This data is available as a global array, via an alternative alias data symbol with weak binding, and via a functional interface. % cat idx5.c int _idx5[5] = { 0, 1, 2, 3, 4 }; #pragma weak idx5 = _idx5 int idx5_func(int index) { if ((index 4)) return (-1); return (_idx5[index]); } A mapfile is required to describe the interface provided by this shared object. % cat mapfile $mapfile_version 2 STUB_OBJECT; SYMBOL_SCOPE { _idx5 { ASSERT { TYPE=data; SIZE=4[5] }; }; idx5 { ASSERT { BINDING=weak; ALIAS=_idx5 }; }; idx5_func; local: *; }; The following main program is used to print all the index values available from the idx5 shared object. % cat main.c #include <stdio.h> extern int _idx5[5], idx5[5], idx5_func(int); int main(int argc, char **argv) { int i; for (i = 0; i The following commands create a stub version of this shared object in a subdirectory named stublib. elfdump is used to verify that the resulting object is a stub. The command used to build the stub differs from that of the real object only in the addition of the -z stub option, and the use of a different output file name. This demonstrates the ease with which stub generation can be added to an existing makefile. % cc -Kpic -G -M mapfile -h libidx5.so.1 idx5.c -o stublib/libidx5.so.1 -zstub % ln -s libidx5.so.1 stublib/libidx5.so % elfdump -d stublib/libidx5.so | grep STUB [11] FLAGS_1 0x4000000 [ STUB ] The main program can now be built, using the stub object to stand in for the real shared object, and setting a runpath that will find the real object at runtime. However, as we have not yet built the real object, this program cannot yet be run. Attempts to cause the system to load the stub object are rejected, as the runtime linker knows that stub objects lack the actual code and data found in the real object, and cannot execute. % cc main.c -L stublib -R '$ORIGIN/lib' -lidx5 -lc % ./a.out ld.so.1: a.out: fatal: libidx5.so.1: open failed: No such file or directory Killed % LD_PRELOAD=stublib/libidx5.so.1 ./a.out ld.so.1: a.out: fatal: stublib/libidx5.so.1: stub shared object cannot be used at runtime Killed We build the real object using the same command as we used to build the stub, omitting the -z stub option, and writing the results to a different file. % cc -Kpic -G -M mapfile -h libidx5.so.1 idx5.c -o lib/libidx5.so.1 Once the real object has been built in the lib subdirectory, the program can be run. % ./a.out [0] 0 0 0 [1] 1 1 1 [2] 2 2 2 [3] 3 3 3 [4] 4 4 4 Mapfile Changes The version 2 mapfile syntax was extended in a number of places to accommodate stub objects. Conditional Input The version 2 mapfile syntax has the ability conditionalize mapfile input using the $if control directive. As you might imagine, these directives are used frequently with ASSERT directives for data, because a given data symbol will frequently have a different size in 32 or 64-bit code, or on differing hardware such as x86 versus sparc. The link-editor maintains an internal table of names that can be used in the logical expressions evaluated by $if and $elif. At startup, this table is initialized with items that describe the class of object (_ELF32 or _ELF64) and the type of the target machine (_sparc or _x86). We found that there were a small number of cases in the Solaris code base in which we needed to know what kind of object we were producing, so we added the following new predefined items in order to address that need: NameMeaning ...... _ET_DYNshared object _ET_EXECexecutable object _ET_RELrelocatable object ...... STUB_OBJECT Directive The new STUB_OBJECT directive informs the link-editor that the object described by the mapfile can be built as a stub object. STUB_OBJECT; A stub shared object is built entirely from the information in the mapfiles supplied on the command line. When the -z stub option is specified to build a stub object, the presence of the STUB_OBJECT directive in a mapfile is required, and the link-editor uses the information in symbol ASSERT attributes to create global symbols that match those of the real object. When the real object is built, the presence of STUB_OBJECT causes the link-editor to verify that the mapfiles accurately describe the real object interface, and that a stub object built from them will provide the same linking interface as the real object it represents. All function and data symbols that make up the external interface to the object must be explicitly listed in the mapfile. The mapfile must use symbol scope reduction ('*'), to remove any symbols not explicitly listed from the external interface. All global data in the object is required to have an ASSERT attribute that specifies the symbol type and size. If the ASSERT BIND attribute is not present, the link-editor provides a default assertion that the symbol must be GLOBAL. If the ASSERT SH_ATTR attribute is not present, or does not specify that the section is one of BITS or NOBITS, the link-editor provides a default assertion that the associated section is BITS. All data symbols that describe the same address and size are required to have ASSERT ALIAS attributes specified in the mapfile. If aliased symbols are discovered that do not have an ASSERT ALIAS specified, the link fails and no object is produced. These rules ensure that the mapfiles contain a description of the real shared object's linking interface that is sufficient to produce a stub object with a completely compatible linking interface. SYMBOL_SCOPE/SYMBOL_VERSION ASSERT Attribute The SYMBOL_SCOPE and SYMBOL_VERSION mapfile directives were extended with a symbol attribute named ASSERT. The syntax for the ASSERT attribute is as follows: ASSERT { ALIAS = symbol_name; BINDING = symbol_binding; TYPE = symbol_type; SH_ATTR = section_attributes; SIZE = size_value; SIZE = size_value[count]; }; The ASSERT attribute is used to specify the expected characteristics of the symbol. The link-editor compares the symbol characteristics that result from the link to those given by ASSERT attributes. If the real and asserted attributes do not agree, a fatal error is issued and the output object is not created. In normal use, the link editor evaluates the ASSERT attribute when present, but does not require them, or provide default values for them. The presence of the STUB_OBJECT directive in a mapfile alters the interpretation of ASSERT to require them under some circumstances, and to supply default assertions if explicit ones are not present. See the definition of the STUB_OBJECT Directive for the details. When the -z stub command line option is specified to build a stub object, the information provided by ASSERT attributes is used to define the attributes of the global symbols provided by the object. ASSERT accepts the following: ALIAS Name of a previously defined symbol that this symbol is an alias for. An alias symbol has the same type, value, and size as the main symbol. The ALIAS attribute is mutually exclusive to the TYPE, SIZE, and SH_ATTR attributes, and cannot be used with them. When ALIAS is specified, the type, size, and section attributes are obtained from the alias symbol. BIND Specifies an ELF symbol binding, which can be any of the STB_ constants defined in <sys/elf.h>, with the STB_ prefix removed (e.g. GLOBAL, WEAK). TYPE Specifies an ELF symbol type, which can be any of the STT_ constants defined in <sys/elf.h>, with the STT_ prefix removed (e.g. OBJECT, COMMON, FUNC). In addition, for compatibility with other mapfile usage, FUNCTION and DATA can be specified, for STT_FUNC and STT_OBJECT, respectively. TYPE is mutually exclusive to ALIAS, and cannot be used in conjunction with it. SH_ATTR Specifies attributes of the section associated with the symbol. The section_attributes that can be specified are given in the following table: Section AttributeMeaning BITSSection is not of type SHT_NOBITS NOBITSSection is of type SHT_NOBITS SH_ATTR is mutually exclusive to ALIAS, and cannot be used in conjunction with it. SIZE Specifies the expected symbol size. SIZE is mutually exclusive to ALIAS, and cannot be used in conjunction with it. The syntax for the size_value argument is as described in the discussion of the SIZE attribute below. SIZE The SIZE symbol attribute existed before support for stub objects was introduced. It is used to set the size attribute of a given symbol. This attribute results in the creation of a symbol definition. Prior to the introduction of the ASSERT SIZE attribute, the value of a SIZE attribute was always numeric. While attempting to apply ASSERT SIZE to the objects in the Solaris ON consolidation, I found that many data symbols have a size based on the natural machine wordsize for the class of object being produced. Variables declared as long, or as a pointer, will be 4 bytes in size in a 32-bit object, and 8 bytes in a 64-bit object. Initially, I employed the conditional $if directive to handle these cases as follows: $if _ELF32 foo { ASSERT { TYPE=data; SIZE=4 } }; bar { ASSERT { TYPE=data; SIZE=20 } }; $elif _ELF64 foo { ASSERT { TYPE=data; SIZE=8 } }; bar { ASSERT { TYPE=data; SIZE=40 } }; $else $error UNKNOWN ELFCLASS $endif I found that the situation occurs frequently enough that this is cumbersome. To simplify this case, I introduced the idea of the addrsize symbolic name, and of a repeat count, which together make it simple to specify machine word scalar or array symbols. Both the SIZE, and ASSERT SIZE attributes support this syntax: The size_value argument can be a numeric value, or it can be the symbolic name addrsize. addrsize represents the size of a machine word capable of holding a memory address. The link-editor substitutes the value 4 for addrsize when building 32-bit objects, and the value 8 when building 64-bit objects. addrsize is useful for representing the size of pointer variables and C variables of type long, as it automatically adjusts for 32 and 64-bit objects without requiring the use of conditional input. The size_value argument can be optionally suffixed with a count value, enclosed in square brackets. If count is present, size_value and count are multiplied together to obtain the final size value. Using this feature, the example above can be written more naturally as: foo { ASSERT { TYPE=data; SIZE=addrsize } }; bar { ASSERT { TYPE=data; SIZE=addrsize[5] } }; Exported Global Data Is Still A Bad Idea As you can see, the additional plumbing added to the Solaris link-editor to support stub objects is minimal. Furthermore, about 90% of that plumbing is dedicated to handling global data. We have long advised against global data exported from shared objects. There are many ways in which global data does not fit well with dynamic linking. Stub objects simply provide one more reason to avoid this practice. It is always better to export all data via a functional interface. You should always hide your data, and make it available to your users via a function that they can call to acquire the address of the data item. However, If you do have to support global data for a stub, perhaps because you are working with an already existing object, it is still easilily done, as shown above. Oracle does not like us to discuss hypothetical new features that don't exist in shipping product, so I'll end this section with a speculation. It might be possible to do more in this area to ease the difficulty of dealing with objects that have global data that the users of the library don't need. Perhaps someday... Conclusions It is easy to create stub objects for most objects. If your library only exports function symbols, all you have to do to build a faithful stub object is to add STUB_OBJECT; and then to use the same link command you're currently using, with the addition of the -z stub option. Happy Stubbing!

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  • How can I display more info in an error message when using NUnit Assert in a loop?

    - by Ian
    Consider the following code: [Test] public void WidgetTest() { foreach (Widget widget in widgets) { Assert.AreEqual(0, widget.SomeValue); } } If one of the asserts fails, I will get a very unhelpful error message like the one below: 1) Test Failure : WidgetTest.TestSomeValue Expected: 0 But was: 1 at WidgetTest.TestSomeValue() So, the question is, how can I get NUnit to display more useful info, such as the name of the widget, or the iteration of the loop, etc? Even a line number would be more helpful, since this is run in automated manner and I'd like to be able to spot the failing assert without debugging into the code.

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  • Can I write a test without any assert in it ?

    - by stratwine
    Hi, I'd like to know if it is "ok" to write a test without any "assert" in it. So the test would fail only when an exception / error has occured. Eg: like a test which has a simple select query, to ensure that the database configuration is right. So when I change some db-configuration, I re-run this test and check if the configuration is right. ? Thanks!

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  • Django: How do I use assert False, sys.exc_info()[0] without showing a system error page?

    - by swisstony
    I'm new to Django and have some code in my views.py like this: try: myfunction() except: assert False, sys.exc_info()[0] This is very helpful because I get an email with lots of useful info if there's an error. The problem is that it also redirects the user to a Webfaction system error page. What I'd like to know is how do I still get the useful error email, but redirect the user to my own error page? Also, is this the best way to be handling errors in Django?

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  • C# Debug.Assert-s use the same error message. Should I promote it to a static variable?

    - by Hamish Grubijan
    I love Asserts but not code duplication, and in several places I use a Debug.Assert which checks for the same condition like so: Debug.Assert(kosherBaconList.SelectedIndex != -1, "An error message along the lines - you should not ever be able to click on edit button without selecting a kosher bacon first."); This is in response to an actual bug, although the actual list does not contain kosher bacon. Anyhow, I can think of two approaches: private static readonly mustSelectKosherBaconBeforeEditAssertMessage = "An error message along the lines - you should not ever be able to " + "click on edit button without selecting a something first."; ... Debug.Assert( kosherBaconList.SelectedIndex != -1, mustSelectKosherBaconBeforeEditAssertMessage) or: if (kosherBaconList.SelectedIndex == -1) { AssertMustSelectKosherBaconBeforeEdit(); } ... [Conditional("DEBUG")] private void AssertMustSelectKosherBaconBeforeEdit() { // Compiler will optimize away this variable. string errorMessage = "An error message along the lines - you should not ever be able to " + "click on edit button without selecting a something first."; Debug.Assert(false, errorMessage); } or is there a third way which sucks less than either one above? Please share. General helpful relevant tips are also welcome.

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  • Is Assert.Fail() considered bad practice?

    - by Mendelt
    I use Assert.Fail a lot when doing TDD. I'm usually working on one test at a time but when I get ideas for things I want to implement later I quickly write an empty test where the name of the test method indicates what I want to implement as sort of a todo-list. To make sure I don't forget I put an Assert.Fail() in the body. When trying out xUnit.Net I found they hadn't implemented Assert.Fail. Of course you can always Assert.IsTrue(false) but this doesn't communicate my intention as well. I got the impression Assert.Fail wasn't implemented on purpose. Is this considered bad practice? If so why? @Martin Meredith That's not exactly what I do. I do write a test first and then implement code to make it work. Usually I think of several tests at once. Or I think about a test to write when I'm working on something else. That's when I write an empty failing test to remember. By the time I get to writing the test I neatly work test-first. @Jimmeh That looks like a good idea. Ignored tests don't fail but they still show up in a separate list. Have to try that out. @Matt Howells Great Idea. NotImplementedException communicates intention better than assert.Fail() in this case @Mitch Wheat That's what I was looking for. It seems it was left out to prevent it being abused in another way I abuse it.

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  • How do I safely Debug.Assert in ASP.NET?

    - by MatthewMartin
    Asserts can't be caught. This is good because some errors I don't want to be wrapped in try/catch, at least not on the development server. But Asserts seem awefully dangerous. If they get onto production, it can hang the ASP.NET server with a msgbox. //Don't want this on prod even if debug=true is in the web.config #if DEBUG //A future client programmer can wrap this in a try{}catch{} if (!EverythingIsOkay) throw new InvalidOperationException("Dagnabbit, programming error"); //This stops the but has less information that an // Exception and hangs the server if this accidentally // runs on production System.Diagnostics.Debug.Assert(!EverythingIsOkay); #endif Is there better way to communicate an violation of a inviolable condition to a developer without risking hanging IIS? UPDATE: After reading the first replies, I guess the answer hinges on a foolproof way to detect when code is running in a development environment and when it is on a production server, or figuring out how to throw an exception that can't be caught and ignored.

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  • How can I assert from Python C code?

    - by Joe
    I'm writing a Python class in C and I want to put assertions in my debug code. assert.h suits me fine. This only gets put in debug compiles so there's no chance of an assert failure impacting a user of the Python code*. I'm trying to divide my 'library' code (which should be separate to the code linked against Python) so I can use it from other C code. My Python methods are therefore thinnish wrappers around my pure-C code. So I can't do this in my 'library' code: if (black == white) { PyErr_SetString(PyExc_RuntimeError, "Remap failed"); } because this pollutes my pure-C code with Python. It's also far uglier than a simple assert(black != white); I believe that the Distutils compiler always sets NDEBUG, which means I can't use assert.h even in debug builds. Mac OS and Linux. Help! *one argument I've heard against asserting in C code called from Python.

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  • NUnit doesn't work well with Assert.AreEqual

    - by stasal
    Hi! I'm new to unit-testing and NUit in particular. I'm just typing some examples from the book which refers to Java and JUnit. But I'm using C# instead. The problem is: I've got a class with overriden methods such as Equals() and GetHashCode(), but when I am trying to compare two objects of this class with Assert.AreEqual() my code is not called, so I get an exception. Assert.True(MyClass.Equals(MyClass2)) does work well. But I don't wanna use this construction instead of Assert.AreEqual(). Where the problem can be? Here is the class: public class Money { public int amount; protected string currency; public Money(int amount, string currency) { this.amount = amount; this.currency = currency; } public new bool Equals(object obj) { if (obj == null) return false; Money money = (Money)obj; return (amount == money.amount) && (Currency().Equals(money.Currency())); } public new int GetHashCode() { return (string.Format("{0}{1}", amount, currency)).GetHashCode(); } public static Money Dollar(int amount) { return new Money(amount, "USD"); } public static Money Franc(int amount) { return new Money(amount, "CHF"); } public Money Times(int multiplier) { return new Money(amount * multiplier, currency); } public string Currency() { return currency; } } And the test method itself: [TestFixture] public class DollarTest { [Test] public void TestMultiplication() { Money five = Money.Dollar(5); Assert.True(Money.Dollar(10).Equals(five.Times(2))); // ok Assert.AreEqual(Money.Dollar(10), five.Times(2)); // fails } } Thanks.

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