decoder: Implement hover for Keyword

decoder/expr_keyword.go

@@ -2,6 +2,7 @@ package decoder
 
 import (
 	"context"
+	"fmt"
 	"strings"
 
 	"github.com/hashicorp/hcl-lang/lang"
@@ -69,7 +70,27 @@ func (kw Keyword) CompletionAtPos(ctx context.Context, pos hcl.Pos) []lang.Candi
 }
 
 func (kw Keyword) HoverAtPos(ctx context.Context, pos hcl.Pos) *lang.HoverData {
-	// TODO
+	eType, ok := kw.expr.(*hclsyntax.ScopeTraversalExpr)
+	if !ok {
+		return nil
+	}
+
+	if len(eType.Traversal) != 1 {
+		return nil
+	}
+
+	if eType.Traversal.RootName() == kw.cons.Keyword {
+		content := fmt.Sprintf("`%s` _%s_", kw.cons.Keyword, kw.cons.FriendlyName())
+		if kw.cons.Description.Value != "" {
+			content += "\n\n" + kw.cons.Description.Value
+		}
+
+		return &lang.HoverData{
+			Content: lang.Markdown(content),
+			Range:   eType.SrcRange,
+		}
+	}
+
 	return nil
 }
 

decoder/expr_keyword_test.go

@@ -136,3 +136,107 @@ func TestCompletionAtPos_exprKeyword(t *testing.T) {
 		})
 	}
 }
+
+func TestHoverAtPos_exprKeyword(t *testing.T) {
+	testCases := []struct {
+		testName          string
+		attrSchema        map[string]*schema.AttributeSchema
+		cfg               string
+		pos               hcl.Pos
+		expectedHoverData *lang.HoverData
+	}{
+		{
+			"mismatching expression type",
+			map[string]*schema.AttributeSchema{
+				"attr": {
+					Constraint: schema.Keyword{
+						Keyword: "foobar",
+					},
+				},
+			},
+			`attr = "foobar"`,
+			hcl.Pos{Line: 1, Column: 12, Byte: 11},
+			nil,
+		},
+		{
+			"mismatching keyword",
+			map[string]*schema.AttributeSchema{
+				"attr": {
+					Constraint: schema.Keyword{
+						Keyword: "foobar",
+					},
+				},
+			},
+			`attr = barfoo`,
+			hcl.Pos{Line: 1, Column: 12, Byte: 11},
+			nil,
+		},
+		{
+			"matching keyword",
+			map[string]*schema.AttributeSchema{
+				"attr": {
+					Constraint: schema.Keyword{
+						Keyword: "foobar",
+					},
+				},
+			},
+			`attr = foobar`,
+			hcl.Pos{Line: 1, Column: 12, Byte: 11},
+			&lang.HoverData{
+				Content: lang.Markdown("`foobar` _keyword_"),
+				Range: hcl.Range{
+					Filename: "test.tf",
+					Start:    hcl.Pos{Line: 1, Column: 8, Byte: 7},
+					End:      hcl.Pos{Line: 1, Column: 14, Byte: 13},
+				},
+			},
+		},
+		{
+			"matching keyword with all metadata",
+			map[string]*schema.AttributeSchema{
+				"attr": {
+					Constraint: schema.Keyword{
+						Keyword:     "foobar",
+						Name:        "custom name",
+						Description: lang.Markdown("custom _description_"),
+					},
+				},
+			},
+			`attr = foobar`,
+			hcl.Pos{Line: 1, Column: 12, Byte: 11},
+			&lang.HoverData{
+				Content: lang.Markdown("`foobar` _custom name_\n\ncustom _description_"),
+				Range: hcl.Range{
+					Filename: "test.tf",
+					Start:    hcl.Pos{Line: 1, Column: 8, Byte: 7},
+					End:      hcl.Pos{Line: 1, Column: 14, Byte: 13},
+				},
+			},
+		},
+	}
+	for i, tc := range testCases {
+		t.Run(fmt.Sprintf("%d-%s", i, tc.testName), func(t *testing.T) {
+			bodySchema := &schema.BodySchema{
+				Attributes: tc.attrSchema,
+			}
+
+			f, _ := hclsyntax.ParseConfig([]byte(tc.cfg), "test.tf", hcl.InitialPos)
+			d := testPathDecoder(t, &PathContext{
+				Schema: bodySchema,
+				Files: map[string]*hcl.File{
+					"test.tf": f,
+				},
+			})
+
+			ctx := context.Background()
+			hoverData, err := d.HoverAtPos(ctx, "test.tf", tc.pos)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			if diff := cmp.Diff(tc.expectedHoverData, hoverData); diff != "" {
+				t.Fatalf("unexpected hover data: %s", diff)
+			}
+		})
+	}
+}