Allow pre-releases when the range uses them

Currently, when a range uses a pre-release, such as 1.0.0-alpha.1 -
1.1.0, all pre-release versions are being rejected when the constraint
is checked because the upper part of the range does include a pre-release.
For example, 1.0.0-alpha.2 should match that range, but it is rejected
right now.

I have updated how we evaluate constraints so that it checks whether a
constraint part uses pre-releases OR the larger constraint range that it
is part of uses a pre-release. When either part of a range uses a
pre-release, the entire range should allow pre-release versions.

Fixes #177

Signed-off-by: Carolyn Van Slyck <me@carolynvanslyck.com>

README.md

@@ -85,7 +85,8 @@ differences to notes between these two methods of comparison.
    different set of rules that are common for ranges with tools like npm/js
    and Rust/Cargo. This includes considering prereleases to be invalid if the
    ranges does not include one. If you want to have it include pre-releases a
-   simple solution is to include `-0` in your range.
+   simple solution is to include `-0` in your range. For example, `~1.2.3-0` or
+   `1.2.3-0 - 1.5.0`.
 3. Constraint ranges can have some complex rules including the shorthand use of
    ~ and ^. For more details on those see the options below.
 

constraints.go

@@ -32,6 +32,10 @@ func NewConstraint(c string) (*Constraints, error) {
 			return nil, fmt.Errorf("improper constraint: %s", v)
 		}
 
+		// If any part of the range uses a pre-release,
+		// then allow pre-release versions to match when the range is checked.
+		var rangeUsesPrerelease bool
+
 		cs := findConstraintRegex.FindAllString(v, -1)
 		if cs == nil {
 			cs = append(cs, v)
@@ -44,7 +48,21 @@ func NewConstraint(c string) (*Constraints, error) {
 			}
 
 			result[i] = pc
+
+			// Check if the range uses a pre-release
+			if !rangeUsesPrerelease && pc.con.Prerelease() != "" {
+				rangeUsesPrerelease = true
+			}
 		}
+
+		if rangeUsesPrerelease {
+			// If any part of the range used a pre-release,
+			// all versions in the range should allow pre-releases
+			for _, pc := range result {
+				pc.allowPrerelease = true
+			}
+		}
+
 		or[k] = result
 	}
 
@@ -202,6 +220,10 @@ type constraint struct {
 	minorDirty bool
 	dirty      bool
 	patchDirty bool
+
+	// allowPrerelease indicates if the constraint should allow pre-releases,
+	// such as when part of a range constraint that uses pre-releases
+	allowPrerelease bool
 }
 
 // Check if a version meets the constraint
@@ -257,6 +279,7 @@ func parseConstraint(c string) (*constraint, error) {
 		cs.minorDirty = minorDirty
 		cs.patchDirty = patchDirty
 		cs.dirty = dirty
+		cs.allowPrerelease = cs.con.Prerelease() != ""
 
 		return cs, nil
 	}
@@ -389,7 +412,7 @@ func constraintGreaterThanEqual(v *Version, c *constraint) (bool, error) {
 	// If there is a pre-release on the version but the constraint isn't looking
 	// for them assume that pre-releases are not compatible. See issue 21 for
 	// more details.
-	if v.Prerelease() != "" && c.con.Prerelease() == "" {
+	if v.Prerelease() != "" && !c.allowPrerelease {
 		return false, fmt.Errorf("%s is a prerelease version and the constraint is only looking for release versions", v)
 	}
 
@@ -404,7 +427,7 @@ func constraintLessThanEqual(v *Version, c *constraint) (bool, error) {
 	// If there is a pre-release on the version but the constraint isn't looking
 	// for them assume that pre-releases are not compatible. See issue 21 for
 	// more details.
-	if v.Prerelease() != "" && c.con.Prerelease() == "" {
+	if v.Prerelease() != "" && !c.allowPrerelease {
 		return false, fmt.Errorf("%s is a prerelease version and the constraint is only looking for release versions", v)
 	}
 
@@ -437,7 +460,7 @@ func constraintTilde(v *Version, c *constraint) (bool, error) {
 	// If there is a pre-release on the version but the constraint isn't looking
 	// for them assume that pre-releases are not compatible. See issue 21 for
 	// more details.
-	if v.Prerelease() != "" && c.con.Prerelease() == "" {
+	if v.Prerelease() != "" && !c.allowPrerelease {
 		return false, fmt.Errorf("%s is a prerelease version and the constraint is only looking for release versions", v)
 	}
 
@@ -469,7 +492,7 @@ func constraintTildeOrEqual(v *Version, c *constraint) (bool, error) {
 	// If there is a pre-release on the version but the constraint isn't looking
 	// for them assume that pre-releases are not compatible. See issue 21 for
 	// more details.
-	if v.Prerelease() != "" && c.con.Prerelease() == "" {
+	if v.Prerelease() != "" && !c.allowPrerelease {
 		return false, fmt.Errorf("%s is a prerelease version and the constraint is only looking for release versions", v)
 	}
 
@@ -498,7 +521,7 @@ func constraintCaret(v *Version, c *constraint) (bool, error) {
 	// If there is a pre-release on the version but the constraint isn't looking
 	// for them assume that pre-releases are not compatible. See issue 21 for
 	// more details.
-	if v.Prerelease() != "" && c.con.Prerelease() == "" {
+	if v.Prerelease() != "" && !c.allowPrerelease {
 		return false, fmt.Errorf("%s is a prerelease version and the constraint is only looking for release versions", v)
 	}
 

constraints_test.go

@@ -374,6 +374,9 @@ func TestConstraintsCheck(t *testing.T) {
 		{"~1.1-alpha", "1.1.1-beta", true},
 		{"~1.1.1-beta", "1.1.1-alpha", false},
 		{"~1.1.1-beta", "1.1.1", true},
+		{constraint: "1.0.0-alpha.1 - 1.0.0", version: "1.0.0-beta.2", check: true},
+		{constraint: "~1.2.3 || 1.2.3-beta.1", version: "1.2.3-beta.1", check: true},
+		{constraint: "~1.2.3 || 1.2.3-beta.1", version: "1.2.3-beta.2", check: false},
 		{"~1.2.3", "1.2.5", true},
 		{"~1.2.3", "1.2.2", false},
 		{"~1.2.3", "1.3.2", false},