Eclipse has some problem re-running single JUnit tests if
the tests are in Junit 3 format, but the JUnit 4 launcher
is used. This was quite unnecessary and the move was not
completed. We still have no JUnit4 test.

This completes the extermination of JUnit3. Most of the
work was global searce/replace using regular expression,
followed by numerous invocarions of quick-fix and organize
imports and verification that we had the same number of
tests before and after.

- Annotations were introduced.
- All references to JUnit3 classes removed
- Half-good replacement for getting the test name. This was
  needed to make the TestRngs work. The initialization of
  TestRngs was also made lazily since we can not longer find
  out the test name in runtime in the @Before methods.
- Renamed test classes to end with Test, with the exception
  of TestTranslateBundle, which fails from Maven
- Moved JGitTestUtil to the junit support bundle

Change-Id: Iddcd3da6ca927a7be773a9c63ebf8bb2147e2d13
Signed-off-by: Robin Rosenberg <robin.rosenberg@dewire.com>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

The referenced bug showed that JGit produced different merge results
compared to C Git. Unit test was added to reproduce the issue. The
problem can be solved by switching to histogram diff algorithm.

Bug: 331078
Change-Id: I54f30afb3a9fef1dbca365ca5f98f4cc846092e3
Signed-off-by: Christian Halstrick <christian.halstrick@sap.com>
Signed-off-by: Philipp Thun <philipp.thun@sap.com>

The diff algorithm which is used by Merge, Cherry-Pick, Rebase
should be configurable. A new configuration parameter "diff.algorithm"
is introduced which currently accepts the values "myers" or
"histogram". Based on this parameter for example the ResolveMerger
will choose a diff algorithm. The reason for this is bug 331078.
This bug shows that JGit is more compatible with C Git when
histogram diff is in place. But since histogram diff is quite new we
need an easy way to fall back to Myers diff.

Bug: 331078
Change-Id: I2549c992e478d991c61c9508ad826d1a9e539ae3
Signed-off-by: Christian Halstrick <christian.halstrick@sap.com>
Signed-off-by: Philipp Thun <philipp.thun@sap.com>

JGit merge algorithm behaved differently from C Git when
we had adjacent modifications. If line 9 was modified by
OURS and line 10 by theirs then C Git will return a
conflict while JGit was seeing this as independent
modifications. This change is not only there to achieve
compatibility, but there where also some really wrong
merge results produced by JGit in the area of adjacent
modifications.

Change-Id: I8d77cb59e82638214e45b3cf9ce3a1f1e9b35c70
Signed-off-by: Christian Halstrick <christian.halstrick@sap.com>

Introduced similar helper methods than in AbstractDiffTestCase.
Then the test cases are much smaller and better understandable.

Change-Id: I2beb4db5a93bd8c0c1238d5d3039cbd6719eee90
Signed-off-by: Christian Halstrick <christian.halstrick@sap.com>

As described in Bug 328551 there was a bug that the merge algorithm
was not always reporting conflicts when the same line was deleted
and modified. This problem was introduced during commit
0c017188b4 when reported conflicts have
been checked for common pre- and suffixes.

This was fixed here by better determining whether after stripping
off common prefixes and suffixes from a conflicting region there
is still some conflicting part left.
I also added a unit test to test this situation.

Bug: 328551
Change-Id: Iec6c9055d00e5049938484a27ab98dda2577afc4
Signed-off-by: Christian Halstrick <christian.halstrick@sap.com>

Instead of making the sequence itself responsible for the equivalence
function, use an external function that is supplied by the caller.
This cleans up the code because we now say cmp.equals(a, ai, b, bi)
instead of a.equals(ai, b, bi).

This refactoring also removes the odd concept of creating different
types of sequences to have different behaviors for whitespace
ignoring.  Instead DiffComparator now supports singleton functions
that apply a particular equivalence algorithm to a type of sequence.

Change-Id: I559f494d81cdc6f06bfb4208f60780c0ae251df9
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

The merge algorithm was reporting conflicts which where to big.

Example: The common base was "ABC", the "ours" version contained
"AB1C" (the addition of "1" after pos 2) and the "theirs" version also
contained "AB1C". We have two potentially conflicting edits in the
same region which happen to bring in exactly the same content. This
should not be a conflict - but was previously reported as
"AB<<<1===1>>>C".

This is fixed by checking every conflicting chunk whether the
conflicting regions have a common prefix or suffix and by removing
this regions from the conflict.

Change-Id: I4dc169b8ef7a66ec6b307e9a956feef906c9e15e
Signed-off-by: Christian Halstrick <christian.halstrick@sap.com>

Adds the file content merge alorithm and tests for merge to jgit.
The merge algorithm:

- Gets as input parameters the common base, the two new contents
  called "ours" and "theirs".

- Computes the Edits from base to ours and from base to theirs with
  the help of MyersDiff.

- Iterates over the edits.

- Independent edits from ours or from theirs will just be applied
  to the result.

- For conflicting edits we first harmonize the ranges of the edits
  so that in the end we have exactly two edits starting and ending
  at the same points in the common base. Then we write the two
  conclicting contents into the result stream.

Change-Id: I411862393e7bf416b6f33ca55ec5af608ff4663
Signed-off-by: Christian Halstrick <christian.halstrick@sap.com>
[sp: Fixed up two awkard comments in documentation.]
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>