diff --git a/terminal/terminal.h b/terminal/terminal.h
index 00f0208b..c8b54e59 100644
--- a/terminal/terminal.h
+++ b/terminal/terminal.h
@@ -1,9 +1,6 @@
 /*
- * Internals of the Terminal structure, for those other modules
- * which need to look inside it. It would be nice if this could be
- * folded back into terminal.c in future, with an abstraction layer
- * to handle everything that other modules need to know about it;
- * but for the moment, this will do.
+ * Internals of the Terminal structure, used by other modules in the
+ * terminal subdirectory and by test suites.
  */
 
 #ifndef PUTTY_TERMINAL_H
diff --git a/test/test_terminal.c b/test/test_terminal.c
new file mode 100644
index 00000000..0f068c1c
--- /dev/null
+++ b/test/test_terminal.c
@@ -0,0 +1,182 @@
+#include "putty.h"
+#include "terminal.h"
+
+void modalfatalbox(const char *p, ...)
+{
+    va_list ap;
+    fprintf(stderr, "FATAL ERROR: ");
+    va_start(ap, p);
+    vfprintf(stderr, p, ap);
+    va_end(ap);
+    fputc('\n', stderr);
+    exit(1);
+}
+
+const char *const appname = "test_lineedit";
+
+char *platform_default_s(const char *name)
+{ return NULL; }
+bool platform_default_b(const char *name, bool def)
+{ return def; }
+int platform_default_i(const char *name, int def)
+{ return def; }
+FontSpec *platform_default_fontspec(const char *name)
+{ return fontspec_new_default(); }
+Filename *platform_default_filename(const char *name)
+{ return filename_from_str(""); }
+
+const struct BackendVtable *const backends[] = { NULL };
+
+typedef struct Mock {
+    Terminal *term;
+    Conf *conf;
+    struct unicode_data ucsdata[1];
+
+    strbuf *context;
+
+    TermWin tw;
+} Mock;
+
+static bool mock_setup_draw_ctx(TermWin *win) { return false; }
+static void mock_draw_text(TermWin *win, int x, int y, wchar_t *text, int len,
+                           unsigned long attrs, int lattrs, truecolour tc) {}
+static void mock_draw_cursor(TermWin *win, int x, int y, wchar_t *text,
+                             int len, unsigned long attrs, int lattrs,
+                             truecolour tc) {}
+static void mock_set_raw_mouse_mode(TermWin *win, bool enable) {}
+static void mock_set_raw_mouse_mode_pointer(TermWin *win, bool enable) {}
+static void mock_palette_set(TermWin *win, unsigned start, unsigned ncolours,
+                             const rgb *colours) {}
+static void mock_palette_get_overrides(TermWin *tw, Terminal *term) {}
+
+static const TermWinVtable mock_termwin_vt = {
+    .setup_draw_ctx = mock_setup_draw_ctx,
+    .draw_text = mock_draw_text,
+    .draw_cursor = mock_draw_cursor,
+    .set_raw_mouse_mode = mock_set_raw_mouse_mode,
+    .set_raw_mouse_mode_pointer = mock_set_raw_mouse_mode_pointer,
+    .palette_set = mock_palette_set,
+    .palette_get_overrides = mock_palette_get_overrides,
+};
+
+static Mock *mock_new(void)
+{
+    Mock *mk = snew(Mock);
+    memset(mk, 0, sizeof(*mk));
+
+    mk->conf = conf_new();
+    do_defaults(NULL, mk->conf);
+
+    init_ucs_generic(mk->conf, mk->ucsdata);
+    mk->ucsdata->line_codepage = CP_ISO8859_1;
+
+    mk->context = strbuf_new();
+
+    mk->tw.vt = &mock_termwin_vt;
+
+    return mk;
+}
+
+static void mock_free(Mock *mk)
+{
+    strbuf_free(mk->context);
+    conf_free(mk->conf);
+    term_free(mk->term);
+    sfree(mk);
+}
+
+static void reset(Mock *mk)
+{
+    term_pwron(mk->term, true);
+    term_size(mk->term, 24, 80, 0);
+    term_set_trust_status(mk->term, false);
+    strbuf_clear(mk->context);
+}
+
+#if 0
+
+static void test_context(Mock *mk, const char *fmt, ...)
+{
+    strbuf_clear(mk->context);
+    va_list ap;
+    va_start(ap, fmt);
+    put_fmtv(mk->context, fmt, ap);
+    va_end(ap);
+}
+
+#endif
+
+static void report_fail(Mock *mk, const char *file, int line,
+                        const char *fmt, ...)
+{
+    printf("%s:%d", file, line);
+    if (mk->context->len)
+        printf(" (%s)", mk->context->s);
+    printf(": ");
+    va_list ap;
+    va_start(ap, fmt);
+    vprintf(fmt, ap);
+    va_end(ap);
+    printf("\n");
+}
+
+static inline void check_iequal(Mock *mk, const char *file, int line,
+                                long long lhs, long long rhs)
+{
+    if (lhs != rhs)
+        report_fail(mk, file, line, "%lld != %lld / %#llx != %#llx",
+                    lhs, rhs, lhs, rhs);
+}
+
+#define IEQUAL(lhs, rhs) check_iequal(mk, __FILE__, __LINE__, lhs, rhs)
+
+static inline void term_datapl(Terminal *term, ptrlen pl)
+{
+    term_data(term, pl.ptr, pl.len);
+}
+
+static struct termchar get_termchar(Terminal *term, int x, int y)
+{
+    termline *tl = term_get_line(term, y);
+    termchar tc;
+    if (0 <= x && x < tl->cols)
+        tc = tl->chars[x];
+    else
+        tc = term->erase_char;
+    term_release_line(tl);
+    return tc;
+}
+
+static void test_hello_world(Mock *mk)
+{
+    /* A trivial test just to kick off this test framework */
+    mk->ucsdata->line_codepage = CP_ISO8859_1;
+
+    reset(mk);
+    term_datapl(mk->term, PTRLEN_LITERAL("hello, world"));
+    IEQUAL(mk->term->curs.x, 12);
+    IEQUAL(mk->term->curs.y, 0);
+    IEQUAL(get_termchar(mk->term, 0, 0).chr, CSET_ASCII | 'h');
+    IEQUAL(get_termchar(mk->term, 1, 0).chr, CSET_ASCII | 'e');
+    IEQUAL(get_termchar(mk->term, 2, 0).chr, CSET_ASCII | 'l');
+    IEQUAL(get_termchar(mk->term, 3, 0).chr, CSET_ASCII | 'l');
+    IEQUAL(get_termchar(mk->term, 4, 0).chr, CSET_ASCII | 'o');
+    IEQUAL(get_termchar(mk->term, 5, 0).chr, CSET_ASCII | ',');
+    IEQUAL(get_termchar(mk->term, 6, 0).chr, CSET_ASCII | ' ');
+    IEQUAL(get_termchar(mk->term, 7, 0).chr, CSET_ASCII | 'w');
+    IEQUAL(get_termchar(mk->term, 8, 0).chr, CSET_ASCII | 'o');
+    IEQUAL(get_termchar(mk->term, 9, 0).chr, CSET_ASCII | 'r');
+    IEQUAL(get_termchar(mk->term, 10, 0).chr, CSET_ASCII | 'l');
+    IEQUAL(get_termchar(mk->term, 11, 0).chr, CSET_ASCII | 'd');
+}
+
+int main(void)
+{
+    Mock *mk = mock_new();
+    mk->term = term_init(mk->conf, mk->ucsdata, &mk->tw);
+
+    test_hello_world(mk);
+
+    mock_free(mk);
+    return 0;
+}
diff --git a/unix/CMakeLists.txt b/unix/CMakeLists.txt
index 33e33d40..0fd96e60 100644
--- a/unix/CMakeLists.txt
+++ b/unix/CMakeLists.txt
@@ -236,3 +236,11 @@ add_executable(test_lineedit
   ${CMAKE_SOURCE_DIR}/stubs/no-timing.c)
 target_link_libraries(test_lineedit
   guiterminal settings eventloop charset utils ${platform_libraries})
+
+add_executable(test_terminal
+  ${CMAKE_SOURCE_DIR}/test/test_terminal.c
+  ${CMAKE_SOURCE_DIR}/stubs/no-gss.c
+  ${CMAKE_SOURCE_DIR}/stubs/no-storage.c
+  ${CMAKE_SOURCE_DIR}/stubs/no-timing.c)
+target_link_libraries(test_terminal
+  guiterminal settings eventloop charset utils ${platform_libraries})
diff --git a/unix/platform.h b/unix/platform.h
index 22ea96eb..a75d70a6 100644
--- a/unix/platform.h
+++ b/unix/platform.h
@@ -333,6 +333,7 @@ void gtk_setup_config_box(
 #define DEFAULT_CODEPAGE 0xFFFF
 #define CP_UTF8 CS_UTF8                /* from libcharset */
 #define CP_437 CS_CP437                /* used for test suites */
+#define CP_ISO8859_1 CS_ISO8859_1      /* used for test suites */
 
 #define strnicmp strncasecmp
 #define stricmp strcasecmp
diff --git a/windows/platform.h b/windows/platform.h
index 0b207473..7a333a0e 100644
--- a/windows/platform.h
+++ b/windows/platform.h
@@ -196,6 +196,7 @@ void centre_window(HWND hwnd);
 #define USES_VTLINE_HACK
 #define CP_UTF8 65001
 #define CP_437 437                     /* used for test suites */
+#define CP_ISO8859_1 0x10001           /* used for test suites */
 
 #ifndef NO_GSSAPI
 /*