feat: support checking versions exist in Pub

tools/osv-linter/internal/pkgchecker/ecosystems.go

@@ -177,7 +177,7 @@ func VersionsExistInEcosystem(pkg string, versions []string, ecosystem string) e
 	case "Packagist":
 		return versionsExistInPackagist(pkg, versions)
 	case "Pub":
-		return nil
+		return versionsExistInPub(pkg, versions)
 	case "PyPI":
 		return versionsExistInPyPI(pkg, versions)
 	case "Red Hat":

tools/osv-linter/internal/pkgchecker/ecosystems_test.go

@@ -422,6 +422,62 @@ func Test_versionsExistInPackagist(t *testing.T) {
 	}
 }
 
+func Test_versionsExistInPub(t *testing.T) {
+	t.Parallel()
+
+	type args struct {
+		pkg      string
+		versions []string
+	}
+	tests := []struct {
+		name    string
+		args    args
+		wantErr bool
+	}{
+		{
+			name: "multiple_versions_which_all_exist",
+			args: args{
+				pkg:      "agent_dart",
+				versions: []string{"0.0.1", "0.1.14+1", "0.1.24", "1.0.0-dev.11"},
+			},
+			wantErr: false,
+		},
+		{
+			name: "multiple_versions_with_one_that_does_not_exist",
+			args: args{
+				pkg:      "agent_dart",
+				versions: []string{"0.1.1", "0.1.15+4", "1.0.0-dev.17"},
+			},
+			wantErr: true,
+		},
+		{
+			name: "an_invalid_version",
+			args: args{
+				pkg:      "agent_dart",
+				versions: []string{"!"},
+			},
+			wantErr: true,
+		},
+		{
+			name: "a_package_that_does_not_exit",
+			args: args{
+				pkg:      "not-a-real-package",
+				versions: []string{"1.0.0"},
+			},
+			wantErr: true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			if err := versionsExistInPub(tt.args.pkg, tt.args.versions); (err != nil) != tt.wantErr {
+				t.Errorf("versionsExistInPub() error = %v, wantErr %v", err, tt.wantErr)
+			}
+		})
+	}
+}
+
 func Test_versionsExistInPyPI(t *testing.T) {
 	t.Parallel()
 

tools/osv-linter/internal/pkgchecker/version_check.go

@@ -264,6 +264,18 @@ func versionsExistInPackagist(pkg string, versions []string) error {
 	)
 }
 
+// Confirm that all specified versions of a package exist in Pub.
+func versionsExistInPub(pkg string, versions []string) error {
+	packageInstanceURL := fmt.Sprintf("%s/%s", EcosystemBaseURLs["Pub"], pkg)
+
+	return versionsExistInGeneric(
+		pkg, versions,
+		"Pub",
+		packageInstanceURL,
+		"versions.#.version",
+	)
+}
+
 // Confirm that all specified versions of a package exist in PyPI.
 func versionsExistInPyPI(pkg string, versions []string) error {
 	// https://packaging.python.org/en/latest/specifications/name-normalization/