CS2103/T Aug '18
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  • Project: DeliverablesProject: Supervision


    Project: Assessment

    Note that project grading is not competitive (not bell curved). CS2103T projects will be assessed separately from CS2103 projects. This is to account for the perceived difference in workload. Given below is the marking scheme.

    Total: 50 marks ( 40 individual marks + 10 team marks)

    Evaluates: How well do your features fit together to form a cohesive product (not how many features or how big the features are)?

    Based on: user guide and the product demo. The quality of the demo will be factored in as well.

    💡 Feature that fit well with the other features will earn more marks.

    Evaluates:

    A. Code quality/quantity:

    How good your implementation is, in terms of the quality and the quantity of the code you have written yourself.

    Based on: an inspection of the parts of the code you claim as written by you.

    • Ensure your code has at least some evidence of these (see here for more info)

      • logging
      • exceptions
      • assertions
      • defensive coding
    • Ensure there are no coding standard violations  e.g. all boolean variables/methods sounds like booleans. Checkstyle can prevent only some coding standard violations; others need to be checked manually.

    • Ensure SLAP is applied at a reasonable level. Long methods or deeply-nested code are symptoms of low-SLAP may be counted against your code quality.

    • Reduce code duplications  i.e. if there multiple blocks of code that vary only in minor ways, try to extract out similarities into one place, especially in test code.

    • In addition, try to apply as many of the code quality guidelines covered in the module as much as you can.

     

    Code Quality

    Introduction

    Basic

    Can explain the importance of code quality

    Always code as if the person who ends up maintaining your code will be a violent psychopath who knows where you live. -- Martin Golding

    Production code needs to be of high quality . Given how the world is becoming increasingly dependent of software, poor quality code is something we cannot afford to tolerate.

    Code being used in an actual product with actual users

    Guideline: Maximise Readability

    Introduction

    Can explain the importance of readability

    Programs should be written and polished until they acquire publication quality. --Niklaus Wirth

    Among various dimensions of code quality, such as run-time efficiency, security, and robustness, one of the most important is understandability. This is because in any non-trivial software project, code needs to be read, understood, and modified by other developers later on. Even if we do not intend to pass the code to someone else, code quality is still important because we all become 'strangers' to our own code someday.

    The two code samples given below achieve the same functionality, but one is easier to read.

         

    Bad

    int subsidy() {
        int subsidy;
        if (!age) {
            if (!sub) {
                if (!notFullTime) {
                    subsidy = 500;
                } else {
                    subsidy = 250;
                }
            } else {
                subsidy = 250;
            }
        } else {
            subsidy = -1;
        }
        return subsidy;
    }
    

      

    Good

    int calculateSubsidy() {
        int subsidy;
        if (isSenior) {
            subsidy = REJECT_SENIOR;
        } else if (isAlreadySubsidised) {
            subsidy = SUBSIDISED_SUBSIDY;
        } else if (isPartTime) {
            subsidy = FULLTIME_SUBSIDY * RATIO;
        } else {
            subsidy = FULLTIME_SUBSIDY;
        }
        return subsidy;
    }
    

         

    Bad

    def calculate_subs():
        if not age:
            if not sub:
                if not not_fulltime:
                    subsidy = 500
                else:
                    subsidy = 250
            else:
                subsidy = 250
        else:
            subsidy = -1
        return subsidy
    

      

    Good

    def calculate_subsidy():
        if is_senior:
            return REJECT_SENIOR
        elif is_already_subsidised:
            return SUBSIDISED_SUBSIDY
        elif is_parttime:
            return FULLTIME_SUBSIDY * RATIO
        else:
            return FULLTIME_SUBSIDY
    

    Basic

    Avoid Long Methods

    Can improve code quality using technique: avoid long methods

    Be wary when a method is longer than the computer screen, and take corrective action when it goes beyond 30 LOC (lines of code). The bigger the haystack, the harder it is to find a needle.

    Avoid Deep Nesting

    Can improve code quality using technique: avoid deep nesting

    If you need more than 3 levels of indentation, you're screwed anyway, and should fix your program. --Linux 1.3.53 CodingStyle

    In particular, avoid arrowhead style code.

    Example:

    Avoid Complicated Expressions

    Can improve code quality using technique: avoid complicated expressions

    Avoid complicated expressions, especially those having many negations and nested parentheses. If you must evaluate complicated expressions, have it done in steps (i.e. calculate some intermediate values first and use them to calculate the final value).

    Example:

    Bad

    return ((length < MAX_LENGTH) || (previousSize != length)) && (typeCode == URGENT);
    

    Good

    
    boolean isWithinSizeLimit = length < MAX_LENGTH;
    boolean isSameSize = previousSize != length;
    boolean isValidCode = isWithinSizeLimit || isSameSize;
    
    boolean isUrgent = typeCode == URGENT;
    
    return isValidCode && isUrgent;
    

    Example:

    Bad

    return ((length < MAX_LENGTH) or (previous_size != length)) and (type_code == URGENT)
    

    Good

    is_within_size_limit = length < MAX_LENGTH
    is_same_size = previous_size != length
    is_valid_code = is_within_size_limit or is_same_size
    
    is_urgent = type_code == URGENT
    
    return is_valid_code and is_urgent
    

    The competent programmer is fully aware of the strictly limited size of his own skull; therefore he approaches the programming task in full humility, and among other things he avoids clever tricks like the plague. -- Edsger Dijkstra

    Avoid Magic Numbers

    Can improve code quality using technique: avoid magic numbers

    When the code has a number that does not explain the meaning of the number, we call that a magic number (as in “the number appears as if by magic”). Using a named constant makes the code easier to understand because the name tells us more about the meaning of the number.

    Example:

         

    Bad

    return 3.14236;
    ...
    return 9;
    

      

    Good

    static final double PI = 3.14236;
    static final int MAX_SIZE = 10;
    ...
    return PI;
    ...
    return MAX_SIZE-1;
    

    Note: Python does not have a way to make a variable a constant. However, you can use a normal variable with an ALL_CAPS name to simulate a constant.

         

    Bad

    return 3.14236
    ...
    return 9
    

      

    Good

    PI = 3.14236
    MAX_SIZE = 10
    ...
    return PI
    ...
    return MAX_SIZE-1
    

    Similarly, we can have ‘magic’ values of other data types.

    Bad

    "Error 1432"  // A magic string!
    

    Make the Code Obvious

    Can improve code quality using technique: make the code obvious

    Make the code as explicit as possible, even if the language syntax allows them to be implicit. Here are some examples:

    • [Java] Use explicit type conversion instead of implicit type conversion.
    • [Java, Python] Use parentheses/braces to show grouping even when they can be skipped.
    • [Java, Python] Use enumerations when a certain variable can take only a small number of finite values. For example, instead of declaring the variable 'state' as an integer and using values 0,1,2 to denote the states 'starting', 'enabled', and 'disabled' respectively, declare 'state' as type SystemState and define an enumeration SystemState that has values 'STARTING', 'ENABLED', and 'DISABLED'.

    Intermediate

    Structure Code Logically

    Can improve code quality using technique: structure code logically

    Lay out the code so that it adheres to the logical structure. The code should read like a story. Just like we use section breaks, chapters and paragraphs to organize a story, use classes, methods, indentation and line spacing in your code to group related segments of the code. For example, you can use blank lines to group related statements together. Sometimes, the correctness of your code does not depend on the order in which you perform certain intermediary steps. Nevertheless, this order may affect the clarity of the story you are trying to tell. Choose the order that makes the story most readable.

    Do Not 'Trip Up' Reader

    Can improve code quality using technique: do not 'trip up' reader

    Avoid things that would make the reader go ‘huh?’, such as,

    • unused parameters in the method signature
    • similar things look different
    • different things that look similar
    • multiple statements in the same line
    • data flow anomalies such as, pre-assigning values to variables and modifying it without any use of the pre-assigned value

    Practice KISSing

    Can improve code quality using technique: practice kissing

    As the old adage goes, "keep it simple, stupid” (KISS). Do not try to write ‘clever’ code. For example, do not dismiss the brute-force yet simple solution in favor of a complicated one because of some ‘supposed benefits’ such as 'better reusability' unless you have a strong justification.

    Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it. --Brian W. Kernighan

    Programs must be written for people to read, and only incidentally for machines to execute. --Abelson and Sussman

    Avoid Premature Optimizations

    Can improve code quality using technique: avoid premature optimizations

    Optimizing code prematurely has several drawbacks:

    • We may not know which parts are the real performance bottlenecks. This is especially the case when the code undergoes transformations (e.g. compiling, minifying, transpiling, etc.) before it becomes an executable. Ideally, you should use a profiler tool to identify the actual bottlenecks of the code first, and optimize only those parts.
    • Optimizing can complicate the code, affecting correctness and understandability
    • Hand-optimized code can be harder for the compiler to optimize (the simpler the code, the easier for the compiler to optimize it). In many cases a compiler can do a better job of optimizing the runtime code if you don't get in the way by trying to hand-optimize the source code.

    A popular saying in the industry is make it work, make it right, make it fast which means in most cases getting the code to perform correctly should take priority over optimizing it. If the code doesn't work correctly, it has no value on matter how fast/efficient it it.

    Premature optimization is the root of all evil in programming. --Donald Knuth

    Note that there are cases where optimizing takes priority over other things e.g. when writing code for resource-constrained environments. This guideline simply a caution that you should optimize only when it is really needed.

    SLAP Hard

    Can improve code quality using technique: SLAP hard

    Avoid varying the level of abstraction within a code fragment. Note: The Productive Programmer (by Neal Ford) calls this the SLAP principle i.e. Single Level of Abstraction Per method.

    Example:

    Bad

    readData();
    salary = basic*rise+1000;
    tax = (taxable?salary*0.07:0);
    displayResult();
    

    Good

    readData();
    processData();
    displayResult();
    
     

    Design → Design Fundamentals → Abstraction →

    What

    Abstraction is a technique for dealing with complexity. It works by establishing a level of complexity we are interested in, and suppressing the more complex details below that level.

    The guiding principle of abstraction is that only details that are relevant to the current perspective or the task at hand needs to be considered. As most programs are written to solve complex problems involving large amounts of intricate details, it is impossible to deal with all these details at the same time. That is where abstraction can help.

    Ignoring lower level data items and thinking in terms of bigger entities is called data abstraction.

    Within a certain software component, we might deal with a user data type, while ignoring the details contained in the user data item such as name, and date of birth. These details have been ‘abstracted away’ as they do not affect the task of that software component.

    Control abstraction abstracts away details of the actual control flow to focus on tasks at a simplified level.

    print(“Hello”) is an abstraction of the actual output mechanism within the computer.

    Abstraction can be applied repeatedly to obtain progressively higher levels of abstractions.

    An example of different levels of data abstraction: a File is a data item that is at a higher level than an array and an array is at a higher level than a bit.

    An example of different levels of control abstraction: execute(Game) is at a higher level than print(Char) which is at a higher than an Assembly language instruction MOV.

    Abstraction is a general concept that is not limited to just data or control abstractions.

    Some more general examples of abstraction:

    • An OOP class is an abstraction over related data and behaviors.
    • An architecture is a higher-level abstraction of the design of a software.
    • Models (e.g., UML models) are abstractions of some aspect of reality.

    Advanced

    Make the Happy Path Prominent

    Can improve code quality using technique: make the happy path prominent

    The happy path (i.e. the execution path taken when everything goes well) should be clear and prominent in your code. Restructure the code to make the happy path unindented as much as possible. It is the ‘unusual’ cases that should be indented. Someone reading the code should not get distracted by alternative paths taken when error conditions happen. One technique that could help in this regard is the use of guard clauses.

    Example:

    Bad

    if (!isUnusualCase) {  //detecting an unusual condition
        if (!isErrorCase) {
            start();    //main path
            process();
            cleanup();
            exit();
        } else {
            handleError();
        }
    } else {
        handleUnusualCase(); //handling that unusual condition
    }
    

    In the code above,

    • Unusual condition detection is separated from their handling.
    • Main path is nested deeply.

    Good

    if (isUnusualCase) { //Guard Clause
        handleUnusualCase();
        return;
    }
    
    if (isErrorCase) { //Guard Clause
        handleError();
        return;
    }
    
    start();
    process();
    cleanup();
    exit();
    

    In contrast, the above code

    • deals with unusual conditions as soon as they are detected so that the reader doesn't have to remember them for long.
    • keeps the main path un-indented.

    Guideline: Follow a Standard

    Introduction

    Can explain the need for following a standard

    One essential way to improve code quality is to follow a consistent style. That is why software engineers follow a strict coding standard (aka style guide).

    The aim of a coding standard is to make the entire code base look like it was written by one person. A coding standard is usually specific to a programming language and specifies guidelines such as the location of opening and closing braces, indentation styles and naming styles (e.g. whether to use Hungarian style, Pascal casing, Camel casing, etc.). It is important that the whole team/company use the same coding standard and that standard is not generally inconsistent with typical industry practices. If a company's coding standards is very different from what is used typically in the industry, new recruits will take longer to get used to the company's coding style.

    💡 IDEs can help to enforce some parts of a coding standard e.g. indentation rules.

    What is the recommended approach regarding coding standards?

    c

    What is the aim of using a coding standard? How does it help?

    Basic

    Can follow simple mechanical style rules

    Learn basic guidelines of the Java coding standard (by OSS-Generic)

    Consider the code given below:

    import java.util.*;
    
    public class Task {
        public static final String descriptionPrefix = "description: ";
        private String description;
        private boolean important;
        List<String> pastDescription = new ArrayList<>(); // a list of past descriptions
    
        public Task(String d) {
          this.description = d;
          if (!d.isEmpty())
              this.important = true;
        }
    
        public String getAsXML() { return "<task>"+description+"</task>"; }
    
        /**
         * Print the description as a string.
         */
        public void printingDescription(){ System.out.println(this); }
    
        @Override
        public String toString() { return descriptionPrefix + description; }
    }
    

    In what ways the code violate the basic guidelines (i.e., those marked with one ⭐️) of the OSS-Generic Java Coding Standard given here?

    Here are three:

    • descriptionPrefix is a constant and should be named DESCRIPTION_PREFIX
    • method name printingDescription() should be named as printDescription()
    • boolean variable important should be named to sound boolean e.g., isImportant

    There are many more.

    Intermediate

    Can follow intermediate style rules

    Go through the provided Java coding standard and learn the intermediate style rules.

    According to the given Java coding standard, which one of these is not a good name?

    b

    Explanation: checkWeight is an action. Naming variables as actions makes the code harder to follow. isWeightValid may be a better name.

    Repeat the exercise in the panel below but also find violations of intermediate level guidelines.

    Consider the code given below:

    import java.util.*;
    
    public class Task {
        public static final String descriptionPrefix = "description: ";
        private String description;
        private boolean important;
        List<String> pastDescription = new ArrayList<>(); // a list of past descriptions
    
        public Task(String d) {
          this.description = d;
          if (!d.isEmpty())
              this.important = true;
        }
    
        public String getAsXML() { return "<task>"+description+"</task>"; }
    
        /**
         * Print the description as a string.
         */
        public void printingDescription(){ System.out.println(this); }
    
        @Override
        public String toString() { return descriptionPrefix + description; }
    }
    

    In what ways the code violate the basic guidelines (i.e., those marked with one ⭐️) of the OSS-Generic Java Coding Standard given here?

    Here are three:

    • descriptionPrefix is a constant and should be named DESCRIPTION_PREFIX
    • method name printingDescription() should be named as printDescription()
    • boolean variable important should be named to sound boolean e.g., isImportant

    There are many more.

    Here's one you are more likely to miss:

    • * Print the description as a string.* Prints the description as a string.

    There are more.

    Guideline: Name Well

    Introduction

    Can explain the need for good names in code

    Proper naming improves the readability. It also reduces bugs caused by ambiguities regarding the intent of a variable or a method.

    There are only two hard things in Computer Science: cache invalidation and naming things. -- Phil Karlton

    Basic

    Use Nouns for Things and Verbs for Actions

    Can improve code quality using technique: use nouns for things and verbs for actions

    Every system is built from a domain-specific language designed by the programmers to describe that system. Functions are the verbs of that language, and classes are the nouns. ― Robert C. Martin, Clean Code: A Handbook of Agile Software Craftsmanship

    Use nouns for classes/variables and verbs for methods/functions.

    Examples:

    Name for a Bad Good
    Class CheckLimit LimitChecker
    method result() calculate()

    Distinguish clearly between single-valued and multivalued variables.

    Examples:

    Good

    Person student;
    ArrayList<Person> students;
    

    Good

    student = Person('Jim')
    students = [Person('Jim'), Person('Alice')]
    

    Use Standard Words

    Can improve code quality using technique: use standard words

    Use correct spelling in names. Avoid 'texting-style' spelling. Avoid foreign language words, slang, and names that are only meaningful within specific contexts/times e.g. terms from private jokes, a TV show currently popular in your country

    Intermediate

    Use Name to Explain

    Can improve code quality using technique: use name to explain

    A name is not just for differentiation; it should explain the named entity to the reader accurately and at a sufficient level of detail.

    Examples:

    Bad Good
    processInput() (what 'process'?) removeWhiteSpaceFromInput()
    flag isValidInput
    temp

    If the name has multiple words, they should be in a sensible order.

    Examples:

    Bad Good
    bySizeOrder() orderBySize()

    Imagine going to the doctor's and saying "My eye1 is swollen"! Don’t use numbers or case to distinguish names.

    Examples:

    Bad Bad Good
    value1, value2 value, Value originalValue, finalValue

    Not Too Long, Not Too Short

    Can improve code quality using technique: not too long, not too short

    While it is preferable not to have lengthy names, names that are 'too short' are even worse. If you must abbreviate or use acronyms, do it consistently. Explain their full meaning at an obvious location.

    Avoid Misleading Names

    Can improve code quality using technique: avoid misleading names

    Related things should be named similarly, while unrelated things should NOT.

    Example: Consider these variables

    • colorBlack : hex value for color black
    • colorWhite : hex value for color white
    • colorBlue : number of times blue is used
    • hexForRed : : hex value for color red

    This is misleading because colorBlue is named similar to colorWhite and colorBlack but has a different purpose while hexForRed is named differently but has very similar purpose to the first two variables. The following is better:

    • hexForBlack hexForWhite hexForRed
    • blueColorCount

    Avoid misleading or ambiguous names (e.g. those with multiple meanings), similar sounding names, hard-to-pronounce ones (e.g. avoid ambiguities like "is that a lowercase L, capital I or number 1?", or "is that number 0 or letter O?"), almost similar names.

    Examples:

    Bad Good Reason
    phase0 phaseZero Is that zero or letter O?
    rwrLgtDirn rowerLegitDirection Hard to pronounce
    right left wrong rightDirection leftDirection wrongResponse right is for 'correct' or 'opposite of 'left'?
    redBooks readBooks redColorBooks booksRead red and read (past tense) sounds the same
    FiletMignon egg If the requirement is just a name of a food, egg is a much easier to type/say choice than FiletMignon

    Guideline: Avoid Unsafe Shortcuts

    Introduction

    Can explain the need for avoiding error-prone shortcuts

    It is safer to use language constructs in the way they are meant to be used, even if the language allows shortcuts. Some such coding practices are common sources of bugs. Know them and avoid them.

    Basic

    Use the Default Branch

    Can improve code quality using technique: use the default branch

    Always include a default branch in case statements.

    Furthermore, use it for the intended default action and not just to execute the last option. If there is no default action, you can use the 'default' branch to detect errors (i.e. if execution reached the default branch, throw an exception). This also applies to the final else of an if-else construct. That is, the final else should mean 'everything else', and not the final option. Do not use else when an if condition can be explicitly specified, unless there is absolutely no other possibility.

    Bad

    if (red) print "red";
    else print "blue";
    

    Good

    if (red) print "red";
    else if (blue) print "blue";
    else error("incorrect input");
    

    Don't Recycle Variables or Parameters

    Can improve code quality using technique: don't recycle variables or parameters

    • Use one variable for one purpose. Do not reuse a variable for a different purpose other than its intended one, just because the data type is the same.
    • Do not reuse formal parameters as local variables inside the method.

    Bad

    double computeRectangleArea(double length, double width) {
        length = length * width;
        return length;
    }
    
    

    Good

    double computeRectangleArea(double length, double width) {
        double area;
        area = length * width;
        return area;
    }
    

    Avoid Empty Catch Blocks

    Can improve code quality using technique: avoid empty catch blocks

    Never write an empty catch statement. At least give a comment to explain why the catch block is left empty.

    Delete Dead Code

    Can improve code quality using technique: delete dead code

    We all feel reluctant to delete code we have painstakingly written, even if we have no use for that code any more ("I spent a lot of time writing that code; what if we need it again?"). Consider all code as baggage you have to carry; get rid of unused code the moment it becomes redundant. If you need that code again, simply recover it from the revision control tool you are using. Deleting code you wrote previously is a sign that you are improving.

    Intermediate

    Minimise Scope of Variables

    Can improve code quality using technique: minimise scope of variables

    Minimize global variables. Global variables may be the most convenient way to pass information around, but they do create implicit links between code segments that use the global variable. Avoid them as much as possible.

    Define variables in the least possible scope. For example, if the variable is used only within the if block of the conditional statement, it should be declared inside that if block.

    The most powerful technique for minimizing the scope of a local variable is to declare it where it is first used. -- Effective Java, by Joshua Bloch

    Resources:

    Minimise Code Duplication

    Can improve code quality using technique: minimise code duplication

    Code duplication, especially when you copy-paste-modify code, often indicates a poor quality implementation. While it may not be possible to have zero duplication, always think twice before duplicating code; most often there is a better alternative.

    This guideline is closely related to the DRY Principle.

    Supplmentary → Principles →

    DRY Principle

    DRY (Don't Repeat Yourself) Principle: Every piece of knowledge must have a single, unambiguous, authoritative representation within a system The Pragmatic Programmer, by Andy Hunt and Dave Thomas

    This principle guards against duplication of information.

    The functionality implemented twice is a violation of the DRY principle even if the two implementations are different.

    The value a system-wide timeout being defined in multiple places is a violation of DRY.

    Guideline: Comment Minimally, but Sufficiently

    Introduction

    Can explain the need for commenting minimally but sufficiently

    Good code is its own best documentation. As you’re about to add a comment, ask yourself, ‘How can I improve the code so that this comment isn’t needed?’ Improve the code and then document it to make it even clearer. --Steve McConnell, Author of Clean Code

    Some think commenting heavily increases the 'code quality'. This is not so. Avoid writing comments to explain bad code. Improve the code to make it self-explanatory.

    Basic

    Do Not Repeat the Obvious

    Can improve code quality using technique: do not repeat the obvious

    If the code is self-explanatory, refrain from repeating the description in a comment just for the sake of 'good documentation'.

    Bad

    // increment x
    x++;
    
    //trim the input
    trimInput();
    

    Write to the Reader

    Can improve code quality using technique: write to the reader

    Do not write comments as if they are private notes to self. Instead, write them well enough to be understood by another programmer. One type of comments that is almost always useful is the header comment that you write for a class or an operation to explain its purpose.

    Examples:

    Bad Reason: this comment will only make sense to the person who wrote it

    // a quick trim function used to fix bug I detected overnight
    void trimInput(){
        ....
    }
    

    Good

    /** Trims the input of leading and trailing spaces */
    void trimInput(){
        ....
    }
    

    Bad Reason: this comment will only make sense to the person who wrote it

    # a quick trim function used to fix bug I detected overnight
    def trim_input():
        ...
    

    Good

    def trim_input():
    """Trim the input of leading and trailing spaces"""
        ...
    

    Intermediate

    Explain WHAT and WHY, not HOW

    Can improve code quality using technique: explain what and why, not how

    Comments should explain what and why aspect of the code, rather than the how aspect.

    What : The specification of what the code supposed to do. The reader can compare such comments to the implementation to verify if the implementation is correct

    Example: This method is possibly buggy because the implementation does not seem to match the comment. In this case the comment could help the reader to detect the bug.

    /** Removes all spaces from the {@code input} */
    void compact(String input){
        input.trim();
    }
    

    Why : The rationale for the current implementation.

    Example: Without this comment, the reader will not know the reason for calling this method.

    // Remove spaces to comply with IE23.5 formatting rules
    compact(input);
    

    How : The explanation for how the code works. This should already be apparent from the code, if the code is self-explanatory. Adding comments to explain the same thing is redundant.

    Example:

    Bad Reason: Comment explains how the code works.

    // return true if both left end and right end are correct or the size has not incremented
    return (left && right) || (input.size() == size);
    

    Good Reason: Code refactored to be self-explanatory. Comment no longer needed.

    
    boolean isSameSize = (input.size() == size) ;
    return (isLeftEndCorrect && isRightEndCorrect) || isSameSize;
    

    null

    B. Depth and completeness of your feature

    Evaluates: How good is your Quality Assurance?

    Based on: 1. your test code 2. our own manual testing 3. your performance in the v1.4 Practical Exam, 4. bugs found during PE.

    Relevant: [Admin Deliverables → Practical Exam ]

     

    Objectives:

    • Evaluate your manual testing skills, product evaluation skills, effort estimation skills
    • Peer-evaluate your product design , implementation effort , documentation quality

    When, where: Week 13 lecture

    Grading:

    • Your performance in the practical exam will be considered for your final grade (under the QA category and under Implementation category, about 10 marks in total).
    • You will be graded based on your effectiveness as a tester (e.g., the percentage of the bugs you found, the nature of the bugs you found) and how far off your evaluation/estimates are from the evaluator consensus. Explanation: we understand that you have limited expertise in this area; hence, we penalize only if your inputs don't seem to be based on a sincere effort to test/evaluate.
    • The bugs found in your product by others will affect your v1.4 marks. You will be given a chance to reject false-positive bug reports.

    Preparation:

    • Ensure that you can access the relevant issue tracker given below:
      -- for PE Dry Run (at v1.3): nus-cs2103-AY1819S1/pe-dry-run
      -- for PE (at v1.4): nus-cs2103-AY1819S1/pe (will open only near the actual PE)

    • Ensure you have access to a computer that is able to run module projects  e.g. has the right Java version.

    • Have a good screen grab tool with annotation features so that you can quickly take a screenshot of a bug, annotate it, and post in the issue tracker.

      • 💡 You can use Ctrl+V to paste a picture from the clipboard into a text box in GitHub issue tracker.
    • Charge your computer before coming to the PE session. The testing venue may not have enough charging points.

    During:

    1. Take note of your team to test. It will be given to you by the teaching team (distributed via IVLE gradebook).
    2. Download from IVLE all files submitted by the team (i.e. jar file, User Guide, Developer Guide, and Project Portfolio Pages) into an empty folder.
    3. [~40 minutes] Test the product and report bugs as described below:
    Testing instructions for PE and PE Dry Run
    • What to test:

      • PE Dry Run (at v1.3):
        • Test the product based on the User Guide (the UG is most likely accessible using the help command).
        • Do system testing first i.e., does the product work as specified by the documentation?. If there is time left, you can do acceptance testing as well i.e., does the product solve the problem it claims to solve?.
      • PE (at v1.4):
        • Test based on the Developer Guide (Appendix named Instructions for Manual Testing) and the User Guide. The testing instructions in the Developer Guide can provide you some guidance but if you follow those instructions strictly, you are unlikely to find many bugs. You can deviate from the instructions to probe areas that are more likely to have bugs.
        • Do system testing only i.e., verify actual behavior against documented behavior. Do not do acceptance testing.
    • What not to test:

      • Omit features that are driven by GUI inputs (e.g. buttons, menus, etc.) Reason: Only CLI-driven features can earn credit, as per given project constraints. Some features might have both a GUI-driven and CLI-driven ways to invoke them, in which case test only the CLI-driven way of invoking it.
      • Omit feature that existed in AB-4.
    • These are considered bugs:

      • Behavior differs from the User Guide
      • A legitimate user behavior is not handled e.g. incorrect commands, extra parameters
      • Behavior is not specified and differs from normal expectations e.g. error message does not match the error
      • Problems in the User Guide e.g., missing/incorrect info
    • Where to report bugs: Post bug in the following issue trackers (not in the team's repo):

    • Bug report format:

      • Post bugs as you find them (i.e., do not wait to post all bugs at the end) because the issue tracker will close exactly at the end of the allocated time.
      • Do not use team ID in bug reports. Reason: to prevent others copying your bug reports
      • Each bug should be a separate issue.
      • Write good quality bug reports; poor quality or incorrect bug reports will not earn credit.
      • Use a descriptive title.
      • Give a good description of the bug with steps to reproduce and screenshots.
      • Assign a severity to the bug report. Bug report without a priority label are considered severity.Low (lower severity bugs earn lower credit):

    Bug Severity labels:

    • severity.Low : A flaw that is unlikely to affect normal operations of the product. Appears only in very rare situations and causes a minor inconvenience only.
    • severity.Medium : A flaw that causes occasional inconvenience to some users but they can continue to use the product.
    • severity.High : A flaw that affects most users and causes major problems for users. i.e., makes the product almost unusable for most users.
    • About posting suggestions:

      • PE Dry Run (at v1.3): You can also post suggestions on how to improve the product. 💡 Be diplomatic when reporting bugs or suggesting improvements. For example, instead of criticising the current behavior, simply suggest alternatives to consider.
      • PE (at v1.4): Do not post suggestions.
    • If the product doesn't work at all: If the product fails catastrophically e.g., cannot even launch, you can test the fallback team allocated to you. But in this case you must inform us immediately after the session so that we can send your bug reports to the correct team.

    1. [~50 minutes] Evaluate the following aspects. Note down your evaluation in a hard copy (as a backup). Submit via TEAMMATES.

      • A. Cohesiveness of product features []: Do the features fit together and match the stated target user and the value proposition?

        • unable to judge: You are unable to judge this aspect for some reason.
        • low: One of these
          • target user is too general  i.e. wider than AB4
          • target user and/or value proposition not clear from the user guide
          • features don't seem to fit together for the most part
        • medium: Some features fit together but some don't.
        • high: All features fit together but the features are not very high value to the target user.
        • excellent: The target user is clearly defined (not too general) and almost all new features are of high-value to the target user. i.e. the product is very attractive to the target user.
      • B. Quality of user docs []: Evaluate based on the parts of the user guide written by the person, as reproduced in the project portfolio. Evaluate from an end-user perspective.

        • unable to judge: Less than 1 page worth of UG content written by the student.
        • low: Hard to understand, often inaccurate or missing important information.
        • medium: Needs some effort to understand; some information is missing.
        • high: Mostly easy to follow. Only a few areas need improvements.
        • excellent: Easy to follow and accurate. Just enough information, visuals, examples etc. (not too much either). Understandable to the target end user.
      • C. Quality of developer docs []: Evaluate based on the developer docs cited/reproduced in the respective project portfolio page. Evaluate from the perspective of a new developer trying to understand how the features are implemented.

        • unable to judge: One of these
          • less than 0.5 pages worth of content.
          • other problems in the document  e.g. looks like included wrong content.
        • low: One of these
          • Very small amount of content (i.e., 0.5 - 1 page).
          • Hardly any use to the reader (i.e., content doesn't make much sense or redundant).
          • Uses ad-hoc diagrams where UML diagrams could have been used instead.
          • Multiple notation errors in UML diagrams.
        • medium: Some diagrams, some descriptions, but does not help the reader that much  e.g. overly complicated diagrams.
        • high: Enough diagrams (at lest two kinds of UML diagrams used) and enough descriptions (about 2 pages worth) but explanations are not always easy to follow.
        • excellent: Easy to follow. Just enough information (not too much). Minimum repetition of content/diagrams. Good use of diagrams to complement text descriptions. Easy to understand diagrams with just enough details rather than very complicated diagrams that are hard to understand.
      • D. Depth of feature []: Evaluate the feature done by the student for difficulty, depth, and completeness. Note: examples given below assume that AB4 did not have the commands edit, undo, and redo.

        • unable to judge: You are unable to judge this aspect for some reason.
        • low : An easy feature  e.g. make the existing find command case insensitive.
        • medium : Moderately difficult feature, barely acceptable implementation  e.g. an edit command that requires the user to type all fields, even the ones that are not being edited.
        • high: One of the below
          • A moderately difficult feature but fully implemented  e.g. an edit command that allows editing any field.
          • A difficult feature with a reasonable implementation but some aspects are not covered  undo/redo command that only allows a single undo/redo.
        • excellent: A difficult feature, all reasonable aspects are fully implemented  undo/redo command that allows multiple undo/redo.
      • E. Amount of work []: Evaluate the amount of work, on a scale of 0 to 30.

        • Consider this PR (history command) as 5 units of effort which means this PR (undo/redo command) is about 15 points of effort. Given that 30 points matches an effort twice as that needed for the undo/redo feature (which was given as an example of an A grade project), we expect most students to be have efforts lower than 20.
        • Consider the main feature only. Exclude GUI inputs, but consider GUI outputs of the feature. Count all implementation/testing/documentation work as mentioned in that person's PPP. Also look at the actual code written by the person. We understand that it is not possible to know exactly which part of the code is for the main feature; make a best-guess judgement call based on the available info.
        • Do not give a high value just to be nice. If your estimate is wildly inaccurate, it means you are unable to estimate the effort required to implement a feature in a project that you are supposed to know well at this point. You will lose marks if that is the case.

    Processing PE Bug Reports:

    There will be a review period for you to respond to the bug reports you received.

    Duration: The review period will start around 1 day after the PE (exact time to be announced) and will last until the following Wednesday midnight. However, you are recommended to finish this task ASAP, to minimize cutting into your exam preparation work.

    Bug reviewing is recommended to be done as a team as some of the decisions need team consensus.

    Instructions for Reviewing Bug Reports

    • First, don't freak out if there are lot of bug reports. Many can be duplicates and some can be false positives. In any case, we anticipate that all of these products will have some bugs and our penalty for bugs is not harsh. Furthermore, it depends on the severity of the bug. Some bug may not even be penalized.

    • Do not edit the subject or the description. Do not close bug reports. Your response (if any) should be added as a comment.

    • If the bug is reported multiple times, mark all copies EXCEPT one as duplicates using the duplicate tag (if the duplicates have different severity levels, you should keep the one with the highest severity). In addition, use this technique to indicate which issue they are duplicates of. Duplicates can be omitted from processing steps given below.

    • If a bug seems to be for a different product (i.e. wrongly assigned to your team), let us know (email prof).

    • Decide if it is a real bug and apply ONLY one of these labels.

    Response Labels:

    • response.Accepted: You accept it as a bug.
    • response.Rejected: What tester treated as a bug is in fact the expected behavior. The penalty for rejecting a bug using an unjustifiable explanation is higher than the penalty if the same bug was accepted. You can reject bugs that you inherited from AB4.
    • response.CannotReproduce: You are unable to reproduce the behavior reported in the bug after multiple tries.
    • response.IssueUnclear: The issue description is not clear.
    • If applicable, decide the type of bug. Bugs without type- are considered type-FunctionalityBug by default (which are liable to a heavier penalty):

    Bug Type Labels:

    • type-FunctionalityBug : the bug is a flaw in how the product works.
    • type-DocumentationBug : the bug is in the documentation.
    • If you disagree with the original severity assigned to the bug, you may change it to the correct level, in which case add a comment justifying the change. All such changes will be double-checked by the teaching team and unreasonable lowering of severity will be penalized extra.:

    Bug Severity labels:

    • severity.Low : A flaw that is unlikely to affect normal operations of the product. Appears only in very rare situations and causes a minor inconvenience only.
    • severity.Medium : A flaw that causes occasional inconvenience to some users but they can continue to use the product.
    • severity.High : A flaw that affects most users and causes major problems for users. i.e., makes the product almost unusable for most users.
    • Decide who should fix the bug. Use the Assignees field to assign the issue to that person(s). There is no need to actually fix the bug though. It's simply an indication/acceptance of responsibility. If there is no assignee, we will distribute the penalty for that bug (if any) among all team members.

    • Add an explanatory comment explaining your choice of labels and assignees.

    • There is no requirement for a minimum coverage level. Note that in a production environment you are often required to have at least 90% of the code covered by tests. In this project, it can be less. The less coverage you have, the higher the risk of regression bugs, which will cost marks if not fixed before the final submission.
    • You must write some tests so that we can evaluate your ability to write tests.
    • How much of each type of testing should you do? We expect you to decide. You learned different types of testing and what they try to achieve. Based on that, you should decide how much of each type is required. Similarly, you can decide to what extent you want to automate tests, depending on the benefits and the effort required.
    • Applying TDD is optional. If you plan to test something, it is better to apply TDD because TDD ensures that you write functional code in a testable way. If you do it the normal way, you often find that it is hard to test the functional code because the code has low testability.

    Evaluates: How good are the sections you wrote for the user guide and the developer guide?

    Based on: the relevant sections of your project portfolio. Criteria considered:

    • Explanation should be clear and written to match the audience.
    • Good use of visuals to complement text.
    • Use of correct UML notations (where applicable)

    A. Process:

    Evaluates: How well you did in project management related aspects of the project, as an individual and as a team

    Based on: Supervisor observations of project milestones and GitHub data.

    Milestones need to be reached the midnight before of the tutorial for it to be counted as achieved. To get a good grade for this aspect, achieve at least 60% of the recommended milestone progress.

    Other criteria:

    • Good use of GitHub milestones
    • Good use of GitHub release mechanism
    • Good version control, based on the repo
    • Reasonable attempt to use the forking workflow
    • Good task definition, assignment and tracking, based on the issue tracker
    • Good use of buffers (opposite: everything at the last minute)
    • Project done iteratively and incrementally (opposite: doing most of the work in one big burst)

    B. Team-based tasks:

    Evaluates: how much you contributed to common team-based tasksteam-based tasks

    Based on: peer evaluations and tutor observations

    Relevant: [Admin Project Scope → Examples of team tasks ]

     

    Here is a non-exhaustive list of team-tasks:

    1. Necessary general code enhancements e.g.,
      1. Work related to renaming the product
      2. Work related to changing the product icon
      3. Morphing the product into a different product
    2. Setting up the GitHub, Travis, AppVeyor, etc.
    3. Maintaining the issue tracker
    4. Release management
    5. Updating user/developer docs that are not specific to a feature  e.g. documenting the target user profile
    6. Incorporating more useful tools/libraries/frameworks into the product or the project workflow (e.g. automate more aspects of the project workflow using a GitHub plugin)


    Project: DeliverablesProject: Supervision