1 files changed, 87 insertions, 0 deletions
diff --git a/internal/textutil/textutil_test.go b/internal/textutil/textutil_test.go
new file mode 100644
index 0000000..3a8cd90
--- /dev/null
+++ b/internal/textutil/textutil_test.go
@@ -0,0 +1,87 @@
+package textutil
+
+import (
+    "regexp"
+    "strings"
+    "testing"
+)
+
+func TestRenderTemplate_Basic(t *testing.T) {
+    out := RenderTemplate("Hello, {{name}}!", map[string]string{"name": "Hex"})
+    if out != "Hello, Hex!" {
+        t.Fatalf("render failed: %q", out)
+    }
+    // No vars
+    if RenderTemplate("x", nil) != "x" { t.Fatal("nil vars changed output") }
+}
+
+func TestStripCodeFences_Variants(t *testing.T) {
+    cases := []struct{ in, want string }{
+        {"```\ncode\n```", "code"},
+        {"```go\npackage x\n```", "package x"},
+        {"no fences", "no fences"},
+        {"\n\n```\ntrim\n```\n", "trim"},
+    }
+    for _, c := range cases {
+        if got := StripCodeFences(c.in); got != c.want {
+            t.Fatalf("strip mismatch: %q != %q", got, c.want)
+        }
+    }
+}
+
+func TestInstructionFromSelection_Markers(t *testing.T) {
+    inputs := []string{
+        ";do it;\ncode",
+        "/* fix */\ncode",
+        "<!-- doc -->\ncode",
+        "// change\ncode",
+        "# tweak\ncode",
+        "-- op\ncode",
+    }
+    for _, in := range inputs {
+        instr, cleaned := InstructionFromSelection(in)
+        if strings.TrimSpace(instr) == "" {
+            t.Fatalf("no instruction for input: %q", in)
+        }
+        // cleaned should not contain the instruction token
+        if strings.Contains(cleaned, instr) {
+            // Allow coincidence only if separated differently; require not exact match on same line
+            first := strings.Split(in, "\n")[0]
+            if strings.Contains(first, instr) {
+                t.Fatalf("instruction not removed: %q", cleaned)
+            }
+        }
+    }
+}
+
+func TestFindFirstInstructionInLine_EarliestWins(t *testing.T) {
+    // Both markers present, earliest should win (strict tag first)
+    line := ";first;  // later"
+    instr, cleaned, ok := FindFirstInstructionInLine(line)
+    if !ok || instr != "first" {
+        t.Fatalf("expected 'first', got %q ok=%v", instr, ok)
+    }
+    if strings.Contains(cleaned, instr) {
+        t.Fatalf("expected cleaned line to remove instr: %q", cleaned)
+    }
+}
+
+func TestFindStrictInlineTag(t *testing.T) {
+    if txt, l, r, ok := FindStrictInlineTag("pre;do;post"); !ok || txt != "do" || l != 3 || r != 7 {
+        t.Fatalf("strict tag parse failed: %q %d %d %v", txt, l, r, ok)
+    }
+    if _, _, _, ok := FindStrictInlineTag("; spaced ;"); ok {
+        t.Fatalf("should reject spaced strict tag")
+    }
+}
+
+// optional: ensure no ANSI codes appear in plain helpers
+func TestNoANSIInHelpers(t *testing.T) {
+    ansi := regexp.MustCompile(`\x1b\[[0-9;]*m`)
+    if ansi.MatchString(RenderTemplate("x", nil)) {
+        t.Fatalf("unexpected ansi in RenderTemplate")
+    }
+    if ansi.MatchString(StripCodeFences("x")) {
+        t.Fatalf("unexpected ansi in StripCodeFences")
+    }
+}