fix: Handle development version increments according to SemVer specif…

…ication (#93)

* refactor: extract version change code to function for testability

* test: add suite for applyChangesToVersion function

* fix: do not increment major version in development versions

According to SemVer 2.0.0 §4 breaking changes do not increment the
major version.

* test: semver incrementation on development versions

lib/gitCommitConvention.js

@@ -1,4 +1,5 @@
 const Git = require("./git");
+const { applyChangesToVersion } = require("./semver");
 
 module.exports = function(convention, commitAnchor = 'HEAD') {
 
@@ -57,16 +58,7 @@ module.exports = function(convention, commitAnchor = 'HEAD') {
       }
     });
 
-    if (changes.breaking > 0) {
-      version.major++;
-      version.minor = 0;
-      version.patch = 0;
-    } else if (changes.feature > 0) {
-      version.minor++;
-      version.patch = 0;
-    } else {
-      version.patch++;
-    }
+    applyChangesToVersion(version, changes);
 
     return `${version.major}.${version.minor}.${version.patch}`;
   }

lib/semver.js

@@ -0,0 +1,27 @@
+function applyChangesToVersion(version, changes) {
+  // SemVer 2.0.0 §4: public api should not be considered stable when major version is 0
+  if (version.major === 0) {
+    // never change major version in development releases
+    if (changes.breaking > 0 || changes.feature > 0) {
+      version.minor++;
+      version.patch = 0;
+    } else {
+      version.patch++;
+    }
+  } else {
+    if (changes.breaking > 0) {
+      version.major++;
+      version.minor = 0;
+      version.patch = 0;
+    } else if (changes.feature > 0) {
+      version.minor++;
+      version.patch = 0;
+    } else {
+      version.patch++;
+    }
+  }
+}
+
+module.exports = {
+  applyChangesToVersion,
+};

test/semver.test.js

@@ -0,0 +1,56 @@
+const { applyChangesToVersion } = require("../lib/semver");
+
+const createApplyChangesTest = (versionString, changesString, expectedString) => {
+  test(`applyChangesToVersion - ${versionString} + ${changesString} -> ${expectedString}`, async () => {
+    // GIVEN
+    const p = s => parseInt(s, 10);
+    const v = versionString.split('.').map(p);
+    const c = changesString.split('.').map(p);
+    const e = expectedString.split('.').map(p);
+    const version = {
+      major: v[0],
+      minor: v[1],
+      patch: v[2],
+    };
+    const changes = {
+      breaking: c[0],
+      feature: c[1],
+      patch: c[2],
+    };
+
+
+    // WHEN
+    applyChangesToVersion(version, changes);
+
+
+    // THEN
+    expect(version).toEqual({
+      major: e[0],
+      minor: e[1],
+      patch: e[2],
+    });
+  });
+};
+
+// XXX
+// createApplyChangesTest("1.0.0", "0.0.0", "1.0.0");
+
+// pure changes (either major, minor or patch) to stable version
+createApplyChangesTest("1.0.0", "0.0.1", "1.0.1");
+createApplyChangesTest("1.0.0", "0.1.0", "1.1.0");
+createApplyChangesTest("1.0.0", "1.0.0", "2.0.0");
+
+// mixed changes (at least two of major, minor or patch) to stable version
+createApplyChangesTest("1.0.0", "0.1.1", "1.1.0");
+createApplyChangesTest("1.0.0", "1.1.0", "2.0.0");
+createApplyChangesTest("1.0.0", "1.0.1", "2.0.0");
+
+// pure changes (either major, minor or patch) to development version
+createApplyChangesTest("0.1.0", "0.0.1", "0.1.1");
+createApplyChangesTest("0.1.0", "0.1.0", "0.2.0");
+createApplyChangesTest("0.1.0", "1.0.0", "0.2.0");
+
+// mixed changes (at least two of major, minor or patch) to development version
+createApplyChangesTest("0.1.0", "0.1.1", "0.2.0");
+createApplyChangesTest("0.1.0", "1.1.0", "0.2.0");
+createApplyChangesTest("0.1.0", "1.0.1", "0.2.0");