Fix another pre-release version bug (#24)

I think at this point we're testing this edge case in all our public
APIs.

Closes flutter#17
Closes #23

Author: nex3

CHANGELOG.md

@@ -1,3 +1,8 @@
+# 1.3.5
+
+* Fix a bug where `VersionRange.intersect()` would return incorrect results for
+  pre-release versions with the same base version number as release versions.
+
 # 1.3.4
 
 * Fix a bug where `VersionRange.allowsAll()`, `VersionRange.allowsAny()`, and

lib/src/version_range.dart

@@ -137,29 +137,26 @@ class VersionRange implements Comparable<VersionRange>, VersionConstraint {
 
     if (other is VersionRange) {
       // Intersect the two ranges.
-      var intersectMin = min;
-      var intersectIncludeMin = includeMin;
-      var intersectMax = max;
-      var intersectIncludeMax = includeMax;
-
-      if (other.min == null) {
-        // Do nothing.
-      } else if (intersectMin == null || intersectMin < other.min) {
+      Version intersectMin;
+      bool intersectIncludeMin;
+      if (allowsLower(this, other)) {
+        if (strictlyLower(this, other)) return VersionConstraint.empty;
         intersectMin = other.min;
         intersectIncludeMin = other.includeMin;
-      } else if (intersectMin == other.min && !other.includeMin) {
-        // The edges are the same, but one is exclusive, make it exclusive.
-        intersectIncludeMin = false;
+      } else {
+        if (strictlyLower(other, this)) return VersionConstraint.empty;
+        intersectMin = this.min;
+        intersectIncludeMin = this.includeMin;
       }
 
-      if (other.max == null) {
-        // Do nothing.
-      } else if (intersectMax == null || intersectMax > other.max) {
+      Version intersectMax;
+      bool intersectIncludeMax;
+      if (allowsHigher(this, other)) {
         intersectMax = other.max;
         intersectIncludeMax = other.includeMax;
-      } else if (intersectMax == other.max && !other.includeMax) {
-        // The edges are the same, but one is exclusive, make it exclusive.
-        intersectIncludeMax = false;
+      } else {
+        intersectMax = this.max;
+        intersectIncludeMax = this.includeMax;
       }
 
       if (intersectMin == null && intersectMax == null) {
@@ -169,18 +166,10 @@ class VersionRange implements Comparable<VersionRange>, VersionConstraint {
 
       // If the range is just a single version.
       if (intersectMin == intersectMax) {
-        // If both ends are inclusive, allow that version.
-        if (intersectIncludeMin && intersectIncludeMax) return intersectMin;
-
-        // Otherwise, no versions.
-        return VersionConstraint.empty;
-      }
-
-      if (intersectMin != null &&
-          intersectMax != null &&
-          intersectMin > intersectMax) {
-        // Non-overlapping ranges, so empty.
-        return VersionConstraint.empty;
+        // Because we already verified that the lower range isn't strictly
+        // lower, there must be some overlap.
+        assert(intersectIncludeMin && intersectIncludeMax);
+        return intersectMin;
       }
 
       // If we got here, there is an actual range.

pubspec.yaml

@@ -1,5 +1,5 @@
 name: pub_semver
-version: 1.3.4
+version: 1.3.5
 author: Dart Team <misc@dartlang.org>
 description: >
  Versions and version constraints implementing pub's versioning policy. This

test/version_range_test.dart

@@ -461,6 +461,14 @@ main() {
       expect(new VersionRange(min: v123, max: v124).intersect(v114).isEmpty,
           isTrue);
     });
+
+    test("with a range with a pre-release min, returns an empty constraint",
+        () {
+      expect(
+          new VersionRange(max: v200)
+              .intersect(new VersionConstraint.parse(">=2.0.0-dev")),
+          equals(VersionConstraint.empty));
+    });
   });
 
   group('union()', () {
@@ -539,6 +547,17 @@ main() {
           equals(new VersionRange(
               min: v003, max: v114, includeMin: true, includeMax: true)));
     });
+
+    test("with a range with a pre-release min, returns a constraint with a gap",
+        () {
+      var result = new VersionRange(max: v200)
+          .union(new VersionConstraint.parse(">=2.0.0-dev"));
+      expect(result, allows(v140));
+      expect(result, doesNotAllow(new Version.parse("2.0.0-alpha")));
+      expect(result, allows(new Version.parse("2.0.0-dev")));
+      expect(result, allows(new Version.parse("2.0.0-dev.1")));
+      expect(result, allows(new Version.parse("2.0.0")));
+    });
   });
 
   group('difference()', () {