Configuring Depth of Flow Analysis

Flow Analysis builds paths through the analyzed code to detect different kinds of problems. Since the analysis of all possible paths that span through the whole application may be infeasible, you can set up the desired level of depth of analysis. A deeper analysis will result in more findings, but the performance will be slower and the memory consumption will increase slightly.

You can specify the depth of analysis by using the test configuration interface in DTP. Go to Report Center> Test Configurations> Static Analysis> Flow Analysis Advanced Settings> Performance> Depth of analysis and choose one of the following options by selecting a radio button:

The depth of Flow Analysis is set to Standard by default.

Setting Timeout Strategy

Apart from the depth of analysis, Flow Analysis uses an additional timeout guard to ensure the analysis completes within a reasonable time. An appropriate strategy can be set by using the test configuration interface in DTP. Go to Report Center> Test Configurations> Static Analysis> Flow Analysis Advanced Settings> Performance> Strategy for Timeouts and choose one of the follow-ing options by selecting a radio button:

The default timeout option is time set to 60 seconds. To get information about the Flow Analysis timeouts that occurred during the analysis, review the Setup Problems section of the report generated after the analysis.

Running Flow Analysis with Swapping of Analysis Data Enabled

In this mode, analysis data is written to disk. Swapping of analysis data uses the same persistent storage and is done in a similar process as incremental analysis. If the analysis is run on a large project, the analysis data that represents a semantical model of the analyzed source code may consume all the memory available for running Flow Analysis. If this occurs, Flow Analysis will remove from memory parts of the analysis data that are not currently necessary and reread it from disk later.

In general, we recommend runningin a large JVM heap configured with the Xmx JVM option. This is to minimize swapping, which results in greater performance. If sufficient memory is available, swapping of analysis data may be disabled, which may speed up code analysis.

You can enable or disable the mode by using the test configuration interface in DTP:

Enable swapping of analysis data to disk:Disabled by default. If this option is disabled, it may result in faster analysis, if you are running Flow Analysis analysis on small to moderate size projects that do not require a lot of memory or when plenty of memory is available (for example, for 64-bit systems).

Configuring Verbosity of Flow Analysis

You can configure the following options by using the test configuration interface in DTP:

Specifying Null-checking Methods

The Null-checking methods option allows you to specify the expected return value when a null parameter is passed to a method. This reduces false positives and excessive paths that would normally be built when the return value for null variables are unknown.

Select the Enabled checkbox and provide the following information:

Null-checking Methods Example

Flow Analysis will analyze methods in the analysis scope. Null-checking method parameterizations are required when the methods are out of the scope of the current analysis (e.g. third-party libraries). The classes Account and AccountManager in the following example are defined in a different assembly and are outside the scope of the analysis. The class AccountManager uses static methods to check Account in following way: 

public class Account
        public int Balance { get; set; }

    public class AccountManager
        public static bool IsNullOrEmpty(Account account)
            return account == null || account.Balance == 0;

And there is the following class, which is analyzed by Flow Analysis’s BD.EXCEPT.NR rule:

public class SomeClass
    void SomeMethod()
        Account account = null;
        //some other actions
        if (!AccountManager.IsNullOrEmpty(account))

Flow Analysis assumes that the return value for the method IsNullOrEmpty() is unknown. This is because the method is not in the analysis scope. Flow Analysis will analyze the if branch and find a violation. Calling the IsNullOrEmpty() method, however, returns true when the variable is null.

By adding AccountManager.IsNullOrEmpty() to the list of methods in the Null-checking Methods parameterization with the specified return value, Flow Analysis will not report a violation if the tracked variable is passed to this method. This is because the if branch will not be analyzed, resulting in an avoided false positive.

Null-checking Methods Restrictions

Methods added to this parameterization should be static methods that have a primitive bool return value. Additionally, null-checking methods can have only one input parameter. These restrictions are managed to avoid excessive complications in parameterization and ensuring that there are no other variables that could affect the result of the null-checking method.

Specifying Resources

The Resources tab allows you to define which resources the BD.RES category (Resources) rules should check. These rules check for the correct usage of all resources that are defined and enabled on this tab.

  1. Specify the type of resource.
  2. Select the Enabled checkbox.
  3. If appropriate/desired, disable the Do not report leaks at termination option.
  4. Click the arrow to expand the Resource Allocators and Resource Closers tabs and complete the tables that open with the information about allocators and closers. Details about completing these tabs are provided below.

Configuring Resource Allocators

The Resource allocators table can be completed with the descriptors of methods that can produce a resource. The table has the following columns:

It is common that allocation methods return an error code to indicate allocation failure. When an allocation method returns a resource, a NULL value normally indicates an allocation failure. When Flow Analysis is looking for resource leaks, it needs to understand if allocation succeeded or failed; this helps it report only missing calls to deallocation methods on paths where allocation actually occurred. In cases where a resource allocator method returns a resource, Flow Analysis assumes that the resource is successfully allocated if the returned value is not NULL.

Configuring Resource Closers

The Resource closers table can be completed with the descriptors of methods that can close a resource. The table has the following columns:

Analyzing Visual Basic Projects

dotTEST analyzes Visual Basic projects with the old parser, as the new parser introduced in release 10.4.0 supports only C# code. If the testing scope includes only Visual Basic code, the old parser is automatically used, and no additional configuration is required. If your testing scope includes both Visual Basic and C# code, the new parser is automatically used and the Visual Basic code is not analyzed. To be able to analyze C# and Visual Basic code in a single analysis run, you need to configure the following option in the file: