feat(finalizeContext): context.previousVersion defaults to a previo…

…us version of generated log

README.md

@@ -125,6 +125,14 @@ Type: `array`
 
 All git semver tags found in the repository. You can't overwrite this value.
 
+##### previousTag
+
+Type: `string` Default: previous tag or the first commit hash if no previous tag.
+
+##### currentTag
+
+Type: `string` Default: current tag or `'v'` + version if no current tag.
+
 #### gitRawCommitsOpts
 
 See the [git-raw-commits](https://github.com/stevemao/git-raw-commits) docs. There are some defaults:

index.js

@@ -122,7 +122,7 @@ function conventinalChangelog(options, context, gitRawCommitsOpts, parserOpts, w
         }
       }
 
-      context.gitSemverTags = tagsObj.value;
+      var gitSemverTags = context.gitSemverTags = tagsObj.value;
       if (tagsObj.state === 'fulfilled') {
         tag = tagsObj.value[options.releaseCount - 1];
       }
@@ -174,8 +174,30 @@ function conventinalChangelog(options, context, gitRawCommitsOpts, parserOpts, w
         },
         parserOpts);
 
-      writerOpts = _.assign(
-        preset.writerOpts || {}, {
+      writerOpts = _.assign({
+          finalizeContext: function(context, writerOpts, commits, keyCommit) {
+            if ((!context.currentTag || !context.previousTag) && keyCommit) {
+              var match = /tag:\s*(.+?)[,\)]/gi.exec(keyCommit.gitTags);
+              var currentTag = context.currentTag = context.currentTag || match ? match[1] : null;
+              var index = gitSemverTags.indexOf(currentTag);
+              var previousTag = context.previousTag = gitSemverTags[index + 1];
+
+              if (!previousTag) {
+                if (options.append) {
+                  context.previousTag = context.previousTag || commits[0].hash;
+                } else {
+                  context.previousTag = context.previousTag || commits[commits.length - 1].hash;
+                }
+              }
+            } else {
+              context.previousTag = context.previousTag || gitSemverTags[0];
+              context.currentTag = context.currentTag || 'v' + context.version;
+            }
+
+            return context;
+          }
+        },
+        preset.writerOpts, {
           reverse: options.append
         },
         writerOpts

package.json

@@ -44,6 +44,7 @@
     "chai": "^3.0.0",
     "concat-stream": "^1.4.10",
     "coveralls": "^2.11.2",
+    "git-tails": "^1.0.0",
     "istanbul": "^0.3.15",
     "jscs": "^2.0.0",
     "jshint": "^2.8.0",

test/test.js

@@ -1,6 +1,7 @@
 'use strict';
 var conventionalChangelog = require('../');
 var expect = require('chai').expect;
+var gitTails = require('git-tails');
 var shell = require('shelljs');
 var through = require('through2');
 var writeFileSync = require('fs').writeFileSync;
@@ -331,7 +332,73 @@ describe('conventionalChangelog', function() {
         expect(i).to.equal(3);
         done();
       }));
+  });
+
+  describe('finalizeContext', function() {
+    var tail;
+
+    before(function(done) {
+      shell.exec('git tag -d v0.1.0');
+      gitTails(function(err, data) {
+        tail = data[data.length - 1].substring(0, 7);
+        done();
+      });
+    });
+
+    it('should make `context.previousTag` default to a previous version of generated log (prepend)', function(done) {
+      var i = 0;
 
+      conventionalChangelog({
+        releaseCount: 0
+      }, {
+        version: '3.0.0'
+      }, {}, {}, {
+        mainTemplate: '{{previousTag}}...{{currentTag}}'
+      })
+        .pipe(through(function(chunk, enc, cb) {
+          chunk = chunk.toString();
+
+          if (i === 0) {
+            expect(chunk).to.equal('v2.0.0...v3.0.0');
+          } else if (i === 1) {
+            expect(chunk).to.equal(tail + '...v2.0.0');
+          }
+
+          i++;
+          cb();
+        }, function() {
+          expect(i).to.equal(2);
+          done();
+        }));
+    });
+
+    it('should make `context.previousTag` default to a previous version of generated log (append)', function(done) {
+      var i = 0;
+
+      conventionalChangelog({
+        releaseCount: 0,
+        append: true
+      }, {
+        version: '3.0.0'
+      }, {}, {}, {
+        mainTemplate: '{{previousTag}}...{{currentTag}}'
+      })
+        .pipe(through(function(chunk, enc, cb) {
+          chunk = chunk.toString();
+
+          if (i === 0) {
+            expect(chunk).to.equal(tail + '...v2.0.0');
+          } else if (i === 1) {
+            expect(chunk).to.equal('v2.0.0...v3.0.0');
+          }
+
+          i++;
+          cb();
+        }, function() {
+          expect(i).to.equal(2);
+          done();
+        }));
+    });
   });
 
   it('should warn if preset is not found', function(done) {