mod/module: add more tests

These tests expose some issues with `module.ImportPath`
that will be fixed in the next CL in this chain.

For #3155

Signed-off-by: Roger Peppe <rogpeppe@gmail.com>
Change-Id: Ieb04af53153957d8435ca59c52fcdb1830922ce4
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1195278
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Unity-Result: CUE porcuepine <cue.porcuepine@gmail.com>

mod/module/module_test.go

@@ -289,6 +289,46 @@ var parseImportPathTests = []struct {
 		Qualifier:         "bar",
 	},
 	wantCanonical: "foo.com/bar@v0",
+}, {
+	testName: "WithPattern",
+	path:     "foo.com/bar/.../blah",
+	want: ImportPath{
+		Path:              "foo.com/bar/.../blah",
+		Version:           "",
+		ExplicitQualifier: false,
+		Qualifier:         "blah",
+	},
+	wantCanonical: "foo.com/bar/.../blah",
+}, {
+	testName: "WithPatternAtEnd",
+	path:     "foo.com/bar/...",
+	want: ImportPath{
+		Path:              "foo.com/bar/...",
+		Version:           "",
+		ExplicitQualifier: false,
+		Qualifier:         "...",
+	},
+	wantCanonical: "foo.com/bar/...",
+}, {
+	testName: "WithUnderscoreLastElement",
+	path:     "foo.com/bar/_foo",
+	want: ImportPath{
+		Path:              "foo.com/bar/_foo",
+		Version:           "",
+		ExplicitQualifier: false,
+		Qualifier:         "_foo",
+	},
+	wantCanonical: "foo.com/bar/_foo",
+}, {
+	testName: "WithHashLastElement",
+	path:     "foo.com/bar/#foo",
+	want: ImportPath{
+		Path:              "foo.com/bar/#foo",
+		Version:           "",
+		ExplicitQualifier: false,
+		Qualifier:         "#foo",
+	},
+	wantCanonical: "foo.com/bar/#foo",
 }}
 
 func TestParseImportPath(t *testing.T) {
@@ -313,3 +353,11 @@ func TestImportPathStringAddsQualifier(t *testing.T) {
 	}
 	qt.Assert(t, qt.Equals(ip.String(), "foo.com/bar@v0:baz"))
 }
+
+func TestImportPathStringAddsQualifierWhenNoVersion(t *testing.T) {
+	ip := ImportPath{
+		Path:      "foo.com/bar",
+		Qualifier: "baz",
+	}
+	qt.Assert(t, qt.Equals(ip.String(), "foo.com/bar"))
+}