This commit introduces integration between MockMvc and HtmlUnit, thus
simplifying end-to-end testing when using HTML-based views and enabling
developers to do the following.

 - Easily test HTML pages using tools such as HtmlUnit, WebDriver, & Geb
   without the need to deploy to a Servlet container

 - Test JavaScript within pages

 - Optionally test using mock services to speed up testing

 - Share logic between in-container, end-to-end tests and
   out-of-container integration tests

Issue: SPR-13158

Due to common usage of @Rollback(false), this commit introduces a new
@Commit annotation that more clearly conveys the intent of the code
while retaining the run-time semantics.

@Commit is in fact meta-annotated with @Rollback(false).

Issue: SPR-13279

Issue: SPR-13276, SPR-13277

Since Spring Framework 2.5, @Rollback has been supported on test
methods, with class-level rollback settings configured via
@TransactionConfiguration; however, allowing @Rollback to be declared
on test classes with method-level declarations overriding class-level
declarations would prove more intuitive than having to declare both
@TransactionConfiguration and @Rollback. Furthermore, the
transactionManager flag in @TransactionConfiguration was made
superfluous many years ago with the introduction of support for a
qualifier in @Transactional.

This commit enables @Rollback to be declared at the class level for
default rollback semantics within test class hierarchies and deprecates
@TransactionConfiguration in favor of @Rollback and @Transactional
qualifiers.

Issue: SPR-13276, SPR-13277

Prior to this change, calling the `setDateHeader` method on a
Spring Test MockHttpServletResponse instance would just store the given
long value in a Map, not writing it as a formatted date String.
Also, calling `getDateHeader` on a MockHttpServletRequest would not
support date strings and could not parse those values.

This can be problematic when testing features related to date headers
such as "Expires", "If-Modified-Since", "Last-Modified", etc.

This commit adds formatting and parsing capabilities to Servlet Mocks
for date strings in HTTP headers.

When formatting dates to Strings, the date format used is the one
preferred by the HTTP RFC. When parsing date Strings, multiple date
formats are supported for better compatibility.

Issue: SPR-11912

SPR-13211 introduced support for reusing mock requests in Spring MVC
Test if the request was created by the the Spring TestContext
Framework. Unfortunately, that change makes it impossible for
MockMvc.perform() to be invoked multiple times within the same test
method without side effects. For example, session attributes and
request parameters are transparently and unexpectedly retained for
subsequent invocations of perform(), causing certain categories of
tests to fail.

This commit reverts the changes introduced in SPR-13211 and introduces
a new MockMvcReuseTests class to serve as regression tests within
Spring's test suite.

Issue: SPR-13260, SPR-13211

HTTP headers such as "Expires", "Last-Modified" all use date
strings like "Tue, 21 Jul 2015 10:00:00 GMT". Prior to this commit,
there was no way to match those header values, besides formatting dates
manually.

This commit introduces a new HeaderResultMatcher to test those date
headers using a long timestamp:

```
this.mockMvc.perform(get("/persons/1").header("If-Modified-Since", now))
  .andExpect(status().isNotModified())
  .andExpect(header().dateValue("Last-Modified", timestamp));
```

Issue: SPR-13263

Use ServletHttpResponse.setDateHeader whenever possible and avoid using
SimpleDateFormat.

Prior to this commit, the Spring MVC Test Framework always created a
new MockHttpServletRequest, disregarding any mock request already
present in Spring Web's RequestContextHolder -- for example, one
created by the ServletTestExecutionListener in the Spring TestContext
Framework (TCF).

This commit modifies MockHttpServletRequestBuilder so that it reuses a
mock request created by the TCF. However,
MockMultipartHttpServletRequestBuilder continues to always create a new
MockMultipartHttpServletRequest since a MockHttpServletRequest created
by the TCF is not directly compatible with a
MockMultipartHttpServletRequest. Furthermore, in order to avoid
unforeseen side effects, MockHttpServletRequestBuilder will always
create a new MockHttpServletRequest if a mock request is present in the
RequestContextHolder but not created by the TCF.

Issue: SPR-13211

Issue: SPR-13067

Issue: SPR-13239

When using the Spring TestContext Framework (TCF) to load a
WebApplicationContext and the Spring MVC Test Framework (MockMvc) to
test a controller, two instances of MockHttpServletRequest will be
created. Due to an ordering issue with regard to population of the
RequestAttributes, it is therefore possible that a filter accesses the
mocked request managed by the TCF, while the controller accesses the
mocked request managed by MockMvc, and this leads to test failures if
the controller expects data from the filter to be present in the
request.

This commit fixes this bug by ensuring that the RequestAttributes
backed by the mocked request managed by MockMvc are stored in the
RequestContextHolder before any filters are invoked by MockMvc.

Issue: SPR-13217

This commit adds additional tests to RequestContextHolderTests that
verify proper support for the MockHttpServletRequest managed by Spring
MVC Test in the following scenarios:

- request-scoped service invoked by controller
- session-scoped service invoked by controller
- custom filter that sets request attributes

Issue: SPR-13211

This commit refactors RequestContextHolderTests in preparation for the
work to be done in SPR-13211.

Issue: SPR-13211

This commit introduces a test that verifies the fix introduced in
6842fd7f.

Issue: SPR-13079

SPR-12429 introduced various `BEFORE_*` modes in `@DirtiesContext`. To
support these new modes, `DirtiesContextTestExecutionListener` (DCTEL)
was updated to support both `BEFORE_*` and `AFTER_*` modes. However,
there is a problem with having DCTEL support `BEFORE_*` modes since it
is typically configured to execute after the
`DependencyInjectionTestExecutionListener` (DITEL), and this leads to
several undesired side effects:

 - The test's `ApplicationContext` is closed by DCTEL *after*
   dependencies have been injected into the test instance.

 - Injected dependencies may therefore attempt to interact with an
   `ApplicationContext` that is no longer _active_.

 - If a test has its `ApplicationContext` injected as a dependency,
   interaction with the context will likely fail since the context has
   been closed.

 - Any `TestExecutionListeners` registered after DCTEL will get a _new_
   `ApplicationContext` if they invoke `getApplicationContext()` on the
   `TestContext`.

This commit fixes these issues by introducing a new
`DirtiesContextBeforeModesTestExecutionListener` (DCBMTEL) that is
registered by default before DITEL. The previous support for `BEFORE_*`
modes has been moved from DCTEL to DCBMTEL. In addition, an
`AbstractDirtiesContextTestExecutionListener` has been extracted from
DCTEL in order to avoid code duplication.

Issue: SPR-13180

Prior to this commit, the Spring MVC Test framework only provided
support for printing debug information about the MvcResult to STDOUT.

This commit introduces support for logging `MvcResult` details at
`DEBUG` level via the Apache Commons Logging API. In addition, this
commit introduces additional `print(..)` variants for printing debug
information to custom output streams and writers.

Specifically, `MockMvcResultHandlers` has been augmented with the
following new static methods:

 - `log()`
 - `print(OutputStream)`
 - `print(Writer)`

Issue: SPR-13171

Prior to this commit, when rendering cookies via `andDo(print())` in
Spring MVC Test, the output for the `MockHttpServletResponse` would
look something like the following:

  Cookies = [javax.servlet.http.Cookie@25084a1e]

The reason is that the Cookie class in javax.servlet-api-3.0.1.jar does
not implement toString(). Consequently, nothing about the cookie's
name, value, etc., is displayed, thereby making the debug output for
cookies next to useless.

This commit improves on this by implementing custom toString() logic
for cookies in debug output in Spring MVC Test. For example, the output
now looks like this (without the newlines):

  Cookies = [[Cookie@47faa49c name = 'enigma', value = '42', \\
            comment = [null], domain = [null], maxAge = -1, \\
            path = [null], secure = false, version = 0, \\
            httpOnly = false]]

In addition, this commit fixes a minor bug for FlashMap debug output if
the FlashMap is empty.

Issue: SPR-13168

Issue: SPR-13165

Prior to this commit, it was only possible to declare SQL statements
via @Sql within external script resources (i.e., classpath or file
system resources); however, many developers have inquired about the
ability to inline SQL statements with @Sql analogous to the support for
inlined properties in @TestPropertySource.

This commit introduces support for declaring _inlined SQL statements_
in `@Sql` via a new `statements` attribute. Inlined statements are
executed after statements in scripts.

Issue: SPR-13159

Prior to this change, `XpathResultMatchers` and more generally the
`MockHttpServletResponse` would default to ISO-8859-1 encoding even when
it's not supposed to. The Servlet/HTTP specs mention this encoding
for all `text/*` mime types when decoding bodies to Strings, but this
issue is about XML Parsers.

XML Parsers should use the encoding:

* defined in the `Content-Type` response header (if available)
* written in the XML declaration of the document
* "guessed" by a built-in auto-detection mechanism

This commit changes the following:

* XPathMatchers now feed the XML parser with byte arrays instead of
decoded Strings
* the response should be written to `MockHttpServletResponse` using
its OutputStream, and not a PrintWriter which defaults to ISO-8859-1

Issue: SPR-12676

Ever since @ActiveProfiles was introduced, the declared active profiles
for integration tests have been sorted in order to support unique cache
key generation; however, there are use cases for which the original
ordering should be retained.

For example, Spring Boot's ConfigFileApplicationListener loads
configuration files for active profiles in the order returned by
Environment.getActiveProfiles(), with the assumption that the ordering
matches the order in which the developer declared the active profiles.

This commit maintains the uniqueness of active profiles declared via
@ActiveProfiles but no longer sorts them.

Issue: SPR-12492

Issue: SPR-11393

The modifications to DefaultMockMvcBuilder performed in conjunction
with SPR-12553 introduced a breaking change: the WebApplicationContext
supplied to DefaultMockMvcBuilder's constructor was *always* stored in
the ServletContext as the root WebApplicationContext, overwriting a
root WebApplicationContext that had been set by the user or by the
Spring TestContext Framework (TCF) -- for example, in
AbstractGenericWebContextLoader. Consequently, the changes in SPR-12553
cause tests that use @ContextHierarchy to fail if web components rely
on the correct WebApplicationContext being stored under the
WebApplicationContext#ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE key.

This commit reverts the breaking changes introduced in SPR-12553: if
the root WebApplicationContext has already been set in the
ServletContext of the WebApplicationContext supplied to
DefaultMockMvcBuilder, no action is taken.

Furthermore, this commit introduces new code to address the initial
intent of SPR-12553. Specifically, if the root WebApplicationContext
has NOT been set in the ServletContext of the WebApplicationContext
supplied to DefaultMockMvcBuilder, the application context hierarchy
will be traversed in search of the root WebApplicationContext, and the
root WebApplicationContext will then be stored under the
ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE key.

Issue: SPR-13075, SPR-12553

Issue: SPR-11393

Spring Framework 4.2 RC1 introduced support for synthesizing an
annotation from an existing annotation in order to provide additional
functionality above and beyond that provided by Java. Specifically,
such synthesized annotations provide support for @AliasFor semantics.
As luck would have it, the same principle can be used to synthesize an
annotation from any map of attributes, and in particular, from an
instance of AnnotationAttributes.

The following highlight the major changes in this commit toward
achieving this goal.

- Introduced AnnotationAttributeExtractor abstraction and refactored
  SynthesizedAnnotationInvocationHandler to delegate to an
  AnnotationAttributeExtractor.

- Extracted code from SynthesizedAnnotationInvocationHandler into new
  AbstractAliasAwareAnnotationAttributeExtractor and
  DefaultAnnotationAttributeExtractor implementation classes.

- Introduced MapAnnotationAttributeExtractor for synthesizing an
  annotation that is backed by a map or AnnotationAttributes instance.

- Introduced a variant of synthesizeAnnotation() in AnnotationUtils
  that accepts a map.

- Introduced findAnnotation(*) methods in AnnotatedElementUtils that
  synthesize merged AnnotationAttributes back into an annotation of the
  target type.

The following classes have been refactored to use the new support for
synthesizing AnnotationAttributes back into an annotation.

- ApplicationListenerMethodAdapter
- TestAnnotationUtils
- AbstractTestContextBootstrapper
- ActiveProfilesUtils
- ContextLoaderUtils
- DefaultActiveProfilesResolver
- DirtiesContextTestExecutionListener
- TestPropertySourceAttributes
- TestPropertySourceUtils
- TransactionalTestExecutionListener
- MetaAnnotationUtils
- MvcUriComponentsBuilder
- RequestMappingHandlerMapping

In addition, this commit also includes changes to ensure that arrays
returned by synthesized annotations are properly cloned first.

Issue: SPR-13067

This commit introduces first-class support for aliases for annotation
attributes. Specifically, this commit introduces a new @AliasFor
annotation that can be used to declare a pair of aliased attributes
within a single annotation or an alias from an attribute in a custom
composed annotation to an attribute in a meta-annotation.

To support @AliasFor within annotation instances, AnnotationUtils has
been overhauled to "synthesize" any annotations returned by "get" and
"find" searches. A SynthesizedAnnotation is an annotation that is
wrapped in a JDK dynamic proxy which provides run-time support for
@AliasFor semantics. SynthesizedAnnotationInvocationHandler is the
actual handler behind the proxy.

In addition, the contract for @AliasFor is fully validated, and an
AnnotationConfigurationException is thrown in case invalid
configuration is detected.

For example, @ContextConfiguration from the spring-test module is now
declared as follows:

    public @interface ContextConfiguration {

        @AliasFor(attribute = "locations")
        String[] value() default {};

        @AliasFor(attribute = "value")
        String[] locations() default {};

        // ...
    }

The following annotations and their related support classes have been
modified to use @AliasFor.

- @ManagedResource
- @ContextConfiguration
- @ActiveProfiles
- @TestExecutionListeners
- @TestPropertySource
- @Sql
- @ControllerAdvice
- @RequestMapping

Similarly, support for AnnotationAttributes has been reworked to
support @AliasFor as well. This allows for fine-grained control over
exactly which attributes are overridden within an annotation hierarchy.
In fact, it is now possible to declare an alias for the 'value'
attribute of a meta-annotation.

For example, given the revised declaration of @ContextConfiguration
above, one can now develop a composed annotation with a custom
attribute override as follows.

    @ContextConfiguration
    public @interface MyTestConfig {

        @AliasFor(
           annotation = ContextConfiguration.class,
           attribute = "locations"
        )
        String[] xmlFiles();

        // ...
    }

Consequently, the following are functionally equivalent.

- @MyTestConfig(xmlFiles = "test.xml")
- @ContextConfiguration("test.xml")
- @ContextConfiguration(locations = "test.xml").

Issue: SPR-11512, SPR-11513

Remove unused imports

In order to simplify configuration of the SpringMethodRule and to ensure
that the correct TestContextManager is always retrieved for the
currently executing test class, this commit introduces a static
TestContextManager cache in SpringClassRule.

In addition, since it is not foreseen that SpringClassRule and
SpringMethodRule should be able to be subclassed, their internal methods
are now private instead of protected.

Issue: SPR-7731

Since Spring Framework 2.5, support for integrating the Spring
TestContext Framework (TCF) into JUnit 4 based tests has been provided
via the SpringJUnit4ClassRunner, but this approach precludes the
ability for tests to be run with alternative runners like JUnit's
Parameterized or third-party runners such as the MockitoJUnitRunner.

This commit remedies this situation by introducing @ClassRule and @Rule
based alternatives to the SpringJUnit4ClassRunner. These rules are
independent of any Runner and can therefore be combined with
alternative runners.

Due to the limitations of JUnit's implementation of rules, as of JUnit
4.12 it is currently impossible to create a single rule that can be
applied both at the class level and at the method level (with access to
the test instance). Consequently, this commit introduces the following
two rules that must be used together.

 - SpringClassRule: a JUnit TestRule that provides the class-level
   functionality of the TCF to JUnit-based tests

 - SpringMethodRule: a JUnit MethodRule that provides the
   instance-level and method-level functionality of the TCF to
   JUnit-based tests

In addition, this commit also introduces the following new JUnit
Statements for use with rules:

 - RunPrepareTestInstanceCallbacks

 - ProfileValueChecker

Issue: SPR-7731