Package de.hsh.graja.modules.junit.api

Class DiffHelper

java.lang.Object

de.hsh.graja.modules.junit.api.DiffHelper

public class DiffHelper
extends Object

This class identifies differences between a sample solution and a student solution class. It returns with a junit assertion error, if there were differences. The differences are returned as a DiffAssertionError, that contains detailed data on the differences.

The DiffHelper class creates a DiffHelper.DiffProcessor object, which is the core processing unit for diff checking. There are four methods to create a DiffHelper.DiffProcessor object:

• compareStrings(String, String) returns a DiffHelper.DiffProcessor object comparing two strings.
• callMain() returns a DiffHelper.DiffProcessor object comparing the console output of two classes' main methods.
• callMethod(String, Object...) returns a DiffHelper.DiffProcessor object comparing the console output generated by the specified method of two different classes.
• executeRunnables(Runnable, Runnable) returns a DiffHelper.DiffProcessor object comparing the console output of the two runnable's run methods.

A typical call flow is

 DiffHelper.callMethod("mymethod", a, b)
    .ofClasses(mypackage.Sample.class, studentClass)
    .pipeToSystemIn("console has\nsome input")
    .normalizeOutput(new StringNormalizer(StringNormalizer.StandardRule.OPT_IGNORE_BLANK_LINES))
    .normalizeOutputExcludedFromDiffSynopsis(new StringNormalizer(StringNormalizer.StandardRule.OPT_IGNORE_ALL_WHITESPACE_AND_NEWLINES))
    .includeExplanationInDiffSynopsis("let's explain, what went wrong with your solution...")
    .start();
 

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	DiffHelper.DiffAssertionError	This error is thrown, when DiffHelper.DiffProcessor detects a difference.
static class	DiffHelper.DiffProcessor	This class realizes a fluent interface when instrumenting the Diff with information used when diffing.

Method Summary

Modifier and Type	Method	Description
static DiffHelper.DiffProcessor	callMain()	This method searches for console output differences between an expected and an observed class when calling the main method for each class.
static DiffHelper.DiffProcessor	callMethod(String methodName, Object... params)	This method searches for console output differences between an expected and an observed class when calling a method for each class.
static DiffHelper.DiffProcessor	compareObjects(Object expected, Object observed)	This method searches for differences between an expected and an observed object after being converted to strings (see compareStrings(String, String).
static DiffHelper.DiffProcessor	compareStrings(String expected, String observed)	This method searches for differences between an expected and an observed string.
static DiffHelper.DiffProcessor	executeRunnables(Runnable teacher, Runnable student)	This method searches for output differences between a runnable instance provided by the teacher and a runnable instance provided by a student.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

callMain

public static DiffHelper.DiffProcessor callMain()

This method searches for console output differences between an expected and an observed class when calling the main method for each class.

A typical call flow is

 DiffHelper.callMain()
    .ofClasses(mypackage.Sample.class, studentClass)
    .pipeToSystemIn("console has\nsome input")
    .normalizeOutput(new StringNormalizer(StringNormalizer.StandardRule.OPT_IGNORE_BLANK_LINES))
    .normalizeOutputExcludedFromDiffSynopsis(new StringNormalizer(StringNormalizer.StandardRule.OPT_IGNORE_ALL_WHITESPACE_AND_NEWLINES))
    .includeExplanationInDiffSynopsis("let's explain, what went wrong with your solution...")
    .start();
 

callMethod

public static DiffHelper.DiffProcessor callMethod(String methodName,
                                                  Object... params)

This method searches for console output differences between an expected and an observed class when calling a method for each class.

A typical call flow is

 DiffHelper.callMethod("mymethod", a, b)
    .ofClasses(mypackage.Sample.class, studentClass)
    .pipeToSystemIn("console has\nsome input")
    .normalizeOutput(new StringNormalizer(StringNormalizer.StandardRule.OPT_IGNORE_BLANK_LINES))
    .normalizeOutputExcludedFromDiffSynopsis(new StringNormalizer(StringNormalizer.StandardRule.OPT_IGNORE_ALL_WHITESPACE_AND_NEWLINES))
    .includeExplanationInDiffSynopsis("let's explain, what went wrong with your solution...")
    .start();
 

Parameters:

methodName - name of static method to call

params - parameters for method call

executeRunnables

public static DiffHelper.DiffProcessor executeRunnables(Runnable teacher,
                                                        Runnable student)

This method searches for output differences between a runnable instance provided by the teacher and a runnable instance provided by a student.

A typical call flow is

 DiffHelper.executeRunnables(rt, rs)
    .pipeToSystemIn("console has\nsome input")
    .normalizeOutput(new StringNormalizer(StringNormalizer.StandardRule.OPT_IGNORE_BLANK_LINES))
    .normalizeOutputExcludedFromDiffSynopsis(new StringNormalizer(StringNormalizer.StandardRule.OPT_IGNORE_ALL_WHITESPACE_AND_NEWLINES))
    .includeExplanationInDiffSynopsis("let's explain, what went wrong with your solution...")
    .start();
 

Parameters:

teacher - a Runnable instance that executes teacher code

student - a Runnable instance that executes student code

compareStrings

public static DiffHelper.DiffProcessor compareStrings(String expected,
                                                      String observed)

This method searches for differences between an expected and an observed string. A typical call flow is

 DiffHelper.compareStrings(e, o)
    .normalizeOutput(new StringNormalizer(StringNormalizer.StandardRule.OPT_IGNORE_BLANK_LINES))
    .normalizeOutputExcludedFromDiffSynopsis(new StringNormalizer(StringNormalizer.StandardRule.OPT_IGNORE_ALL_WHITESPACE_AND_NEWLINES))
    .includeExplanationInDiffSynopsis("let's explain, what went wrong with your solution...")
    .start();
 

Parameters:

expected - expected string

observed - observed string

compareObjects

public static DiffHelper.DiffProcessor compareObjects(Object expected,
                                                      Object observed)

This method searches for differences between an expected and an observed object after being converted to strings (see compareStrings(String, String).

Parameters:

expected - expected object

observed - observed object