DogmaSolutions.Analyzers 1.0.53

Dogma Solutions Roslyn Analyzers

A set of Roslyn Analyzer aimed to enforce some design good practices and code quality (QA) rules.

Rules structure

This section describes the rules included into this package.

Every rule is accompanied by the following information and clues:

• Category → identify the area of interest of the rule, and can have one of the following values: Design / Naming / Style / Usage / Performance / Security
• Severity → state the default severity level of the rule. The severity level can be changed by editing the .editorconfig file used by the project/solution. Possible values are enumerated by the DiagnosticSeverity enum
• Description, motivations and fixes → a detailed explanation of the detected issue, and a brief description on how to change your code in order to solve it.
• See also → a list of similar/related rules, or related knownledge base

Rules list

DSA001

Don't use Entity Framework to launch LINQ queries in a WebApi controller.

• Category: Design
• Severity: Warning ⚠
• Related rules: DSA002

Description

WebApi controller methods should not contain data-manipulation business logics through a LINQ query expression.
In the analyzed code, a WebApi controller method is using Entity Framework DbContext to directly manipulate data through a LINQ query expression.
WebApi controllers should not contain data-manipulation business logics.

See also

This is a typical violation of the "Single Responsibility" rule of the "SOLID" principles, because the controller is doing too many things outside its own purpose.

Fix / Mitigation

In order to fix the problem, the code could be modified in order to rely on the "Indirection pattern" and maximize the "Low coupling evalutative pattern" of the "GRASP" principles. Move the data-manipulation business logics into a more appropriate class, or even better, an injected service.

Code sample

public class MyEntitiesController : ControllerBase
{
 protected MyDbContext DbContext { get; }

 public MyEntitiesController(MyDbContext dbContext)
 {
     DbContext = dbContext;
 }

 [HttpGet]
 public IEnumerable<MyEntity> GetAll_NotOk()
 {
     // this WILL trigger the rule
     var query = from entities in DbContext.MyEntities where entities.Id > 0 select entities;
     return query.ToList(); 
 }

 [HttpPost]
 public IEnumerable<long> GetAll_Ok()
 {
     // this WILL NOT trigger the rule
     var query = DbContext.MyEntities.Where(entities => entities.Id > 0).Select(entities=>entities.Id);
     return query.ToList(); 
 }
}

DSA002

Don't use an Entity Framework DbSet to launch queries in a WebApi controller.

• Category: Design
• Severity: Warning ⚠
• Related rules: DSA001

Description

WebApi controller methods should not contain data-manipulation business logics through a LINQ fluent query.
In the analyzed code, a WebApi controller method is using Entity Framework DbSet to directly manipulate data through a LINQ fluent query.
WebApi controllers should not contain data-manipulation business logics.

See also

This is a typical violation of the "Single Responsibility" rule of the "SOLID" principles, because the controller is doing too many things outside its own purpose.

Fix / Mitigation

In order to fix the problem, the code could be modified in order to rely on the "Indirection pattern" and maximize the "Low coupling evalutative pattern" of the "GRASP" principles.
Move the data-manipulation business logics into a more appropriate class, or even better, an injected service.

Code sample

public class MyEntitiesController : Microsoft.AspNetCore.Mvc.ControllerBase
{
 protected MyDbContext DbContext { get; }

 public MyEntitiesController(MyDbContext dbContext)
 {
     this.DbContext = dbContext;
 }

 [HttpGet]
 public IEnumerable<MyEntity> GetAll0()
 {
     // this WILL NOT trigger the rule
     var query = from entities in DbContext.MyEntities where entities.Id > 0 select entities;
     return query.ToList(); 
 }

 [HttpPost]
 public IEnumerable<long> GetAll1()
 {
     // this WILL trigger the rule
     var query = DbContext.MyEntities.Where(entities => entities.Id > 0).Select(entities=>entities.Id);
     return query.ToList(); 
 }
}

DSA003

Use IsNullOrWhiteSpace instead of String.IsNullOrEmpty.

• Category: Code smells
• Severity: Warning ⚠

Description

Usually, business logics distinguish between "string with content", and "string NULL or without meaningfull content".
Thus, statistically speaking, almost every call to string.IsNullOrEmpty could or should be replaced by a call to string.IsNullOrWhiteSpace, because in the large majority of cases, a string composed by only spaces, tabs, and return chars is not considered valid because it doesn't have "meaningfull content".
In most cases, string.IsNullOrEmpty is used by mistake, or has been written when string.IsNullOrWhiteSpace was not available.

Fix / Mitigation

Don't use string.IsNullOrEmpty. Use string.IsNullOrWhiteSpace instead.

Code sample

public class MyClass
{

 public bool IsOk(string s)
 {
     // this WILL NOT trigger the rule
     return string.IsNullOrWhiteSpace(s);
 }

 public bool IsNotOk(string s)
 {
     // this WILL trigger the rule
     return string.IsNullOrEmpty(s);
 }

}

DSA004

Use DateTime.UtcNow instead of DateTime.Now.

• Category: Code smells
• Severity: Warning ⚠

Description

Using DateTime.Now into business logics potentially leads to many different problems:

• Incoherence between nodes or processes running in different timezones (even in the same country, i.e. USA, Soviet Union, China, etc)
• Unexpected behaviours in-between legal time changes
• Code conversion problems and loss of timezone info when saving/loading data to/from a datastore

See also

Security-wise, this is correlated to the CWE category “7PK” (CWE-361)
Cit: "This category represents one of the phyla in the Seven Pernicious Kingdoms vulnerability classification. It includes weaknesses related to the improper management of time and state in an environment that supports simultaneous or near-simultaneous computation by multiple systems, processes, or threads. According to the authors of the Seven Pernicious Kingdoms, "Distributed computation is about time and state. That is, in order for more than one component to communicate, state must be shared, and all that takes time. Most programmers anthropomorphize their work. They think about one thread of control carrying out the entire program in the same way they would if they had to do the job themselves. Modern computers, however, switch between tasks very quickly, and in multi-core, multi-CPU, or distributed systems, two events may take place at exactly the same time. Defects rush to fill the gap between the programmer's model of how a program executes and what happens in reality. These defects are related to unexpected interactions between threads, processes, time, and information. These interactions happen through shared state: semaphores, variables, the file system, and, basically, anything that can store information."

Fix / Mitigation

Don't use DateTime.Now. Use DateTime.UtcNow instead

Code sample

public class MyClass
{

 public bool IsOk(string s)
 {
     // this WILL NOT trigger the rule
     return string.IsNullOrWhiteSpace(s);
 }

 public bool IsNotOk(string s)
 {
     // this WILL trigger the rule
     return string.IsNullOrEmpty(s);
 }

}

DSA005

Potential non-deterministic point-in-time execution due to multiple usages of DateTime.UtcNow or DateTime.Now in the same method.

• Category: Code smells
• Severity: Error ⛔

Description

An execution flow must always be as deterministic as possible. This means that all decisions inside a scope or algorithm must be performed on a "stable" and immutable set of parameters/conditions. When dealing with dates and times, always ensure that the point-in-time reference is fixed, otherwise the algorithm would work on a "sliding window", leading to unpredictable results. This is particularly impacting in:

• datasource-dependent flows
• slow-running algorithms
• and in-between legal time changes.

See also

Security-wise, this is correlated to the CWE category “7PK” (CWE-361)
Cit: "This category represents one of the phyla in the Seven Pernicious Kingdoms vulnerability classification. It includes weaknesses related to the improper management of time and state in an environment that supports simultaneous or near-simultaneous computation by multiple systems, processes, or threads. According to the authors of the Seven Pernicious Kingdoms, "Distributed computation is about time and state. That is, in order for more than one component to communicate, state must be shared, and all that takes time. Most programmers anthropomorphize their work. They think about one thread of control carrying out the entire program in the same way they would if they had to do the job themselves. Modern computers, however, switch between tasks very quickly, and in multi-core, multi-CPU, or distributed systems, two events may take place at exactly the same time. Defects rush to fill the gap between the programmer's model of how a program executes and what happens in reality. These defects are related to unexpected interactions between threads, processes, time, and information. These interactions happen through shared state: semaphores, variables, the file system, and, basically, anything that can store information."

Fix/Mitigation

In order to avoid problems, set a var now = DateTime.UtcNow variable at the top of the method, or at the beginning of an execution flow/algorithm, and reuse that variable in all places instead of DateTime.***Now

Code sample

public class MyClass
{

 public bool IsOk(string s)
 {     
     var now = DateTime.UtcNow; // fixed point-in-time reference
     
     DoSomething(now); // this WILL NOT trigger the rule
     
     for(int i; i < 10; i++)
     {
       DoOtherThings(now);  // this WILL NOT trigger the rule
     }
 }

 public bool IsNotOk(string s)
 {   
     DoSomething(DateTime.UtcNow); // this WILL trigger the rule
     
     for(int i; i < 10; i++)
     {
       DoOtherThings(DateTime.UtcNow);  // this WILL trigger the rule
     }
 }

}

Installation

Just download and install the NuGet package

https://www.nuget.org/packages/DogmaSolutions.Analyzers